Legends – Controlling How Features Are Displayed
The Legend
Everyone is familiar with legends on paper maps. They are the keys to understanding the contents of any map. Through a combination of symbols, colors, and text they document the design, meaning, and relationships of the map’s components. The digital legends in GeoMedia accomplish all of these things and more, coupling traditional legend documentation with powerful interactive tools that allow you to "drive" the map window. Understanding and using the legend is the key to effectively using GeoMedia displays.
With proper use of the legend you can create visually exciting maps. Through the legend you customize map objects to facilitate the analytical requirements of your workflow by controlling which objects are displayed, how they are displayed, and how they behave at various scale settings. The visualization and presentation requirements of your workflow are accomplished by manipulating the legend. The legend is also an important tool in the preparation of finished cartographic output.
Legend Description
The legend is an integral part of GeoMedia. The legend is the vehicle used to control the content of the map window and the design the appearance of that content. In other words, it is the dynamic control center for the map window.
The suite of tools that comprise legend functionality operates on three levels. First, interactive control of the appearance and behavior of graphics in the map window is available within the legend at the legend entry level. Second, the Legend Properties dialog allows you to control the overall appearance of the legend and the individual legend entries. Lastly there is a set of commands that allow you to manage legends as a group.
This chapter presents an overview of legend content to get you started working in the map window. This is followed by a step-by-step discussion of techniques and procedures for legend manipulation from the Legend Properties dialog. Chapter 12 discusses the application of graphic styles to map objects in the legend, and Chapter 13 covers overall legend management.
When you open a new GeoWorkspace, the application window is, by default, composed of a coordinate system, an empty map window, and an empty legend. What you can display in the map window is a function of the feature tables and imagery pointers stored in your connected warehouses. As your workflow grows, map window displays will be populated with feature class geometry and imagery, as well as the results of the queries and thematic displays you have developed in the GeoWorkspace. By adding a feature class, query, thematic display, labels, or an image to the legend, you create an entry for it in the legend and GeoMedia creates a graphic display of the geometry in the map window.
The legend is stored in the GeoWorkspace when the workspace is saved. You have the option to assign a name to your legend before you save the workspace, which allows you to later associate particular styles and map designs stored in the named legend with new map windows.
Creating Legend Entries
A legend entry is created from one of the Legend > Add menus accessed from either the Main Menu bar or from the Legend toolbar. There are different dialogs for adding feature classes, queries, images, and thematics. The Add Feature Class dialog presents you with a list of all graphic feature classes contained in each warehouse to which your workspace is connected. Graphic feature classes are groups of similar things for which geometry has been created, such as highways, streams, or light poles. In older GIS systems, a feature class might have been called a theme or a layer. A feature class is simply all the records in a single table in a database.
The topmost box in the Legend > Add Feature Class dialog, Connection, shown in the following illustration, allows you to select databases. You click on the down arrow beside the box to select a different warehouse connection from the drop-down list.
ORIGINAL GRAPHIC ig090001
You can display as many feature classes as you desire from this list. To select entries adjacent to each other in the list, click on them while depressing the Shift key. To select multiple items that are not adjacent, highlight them while holding down the Control key. Remember that you may have multiple connections open and that you can display feature classes from any or all connections. Every item in the feature class will be assigned same symbology (i.e., the same color, line styles, fonts, and so on) when it is added to the legend.
Some notes about feature class display are in order. GeoMedia does not honor the symbology of the source data. When you add features to the legend, GeoMedia ignores the style attributes assigned to the graphics in the original project or coverage. In the absence of a named legend (discussed in Chapter 13), display properties for line weight, line style, color, and area fill are generated dynamically from the style attributes stored in the master legend (also discussed in Chapter 13).
This idea also applies to data that have been imported into Access databases as well. The original symbology is not stored in the database at import time. If there is no preexisting legend entry, data that has been imported into an Access warehouse will also have display styles created dynamically when the feature is added to the legend. Regardless of the type of data server connection in place, neither the default symbology assigned to graphics nor user-defined symbology has any effect on source data. The graphic style associated with feature class display operates exclusively in the GeoWorkspace. It is saved when the workspace is saved, and can be maintained via master legend or named legend functionality.
The Add Query dialog looks similar to the Add Feature Class dialog. It contains a list of all named queries saved in the workspace. For example, suppose you had queried a warehouse for all the streets that were asphalt, two-lane, and surfaced within the last six months. This might be saved as the named query recent_asphalt. Using the Legend > Add Query option you could add these streets to your display and, using the legend style dialog, associate a specific color, line style, and so on to them. Query display properties are preserved if the query is an entry in a legend when the workspace is saved and when a query is an entry in a named legend allowing you to display the query with the same symbols later. There is no master legend functionality associated with queries.
The Legend > Add Image dialog contains a list of the path designations that point to raster images to be used as map window backdrops. Unlike feature classes and queries, imagery is handled quite differently because it is raster data. The adjustments that can be made to image display properties are discussed in Chapter 14.
The Legend > Add Thematic dialog is unique. In this dialog you actually construct the thematic display you want to see. Thematic displays are not reusable in the same sense as queries. They cannot be named and stored in a workspace as queries can. As such, they are relatively volatile. They exist as long as they are represented by an entry in the legend. They are saved in the legend in the workspace, but if they are deleted from the legend, they must be recreated. See Chapter 22 for a complete discussion of thematic displays.
Workflow 11-1:
Adding Feature Classes to a Legend
With your GeoWorkspace configured and a connection to a data warehouse established and opened, you are ready to add features to the map and data windows. The tool you will use is the map legend. The GeoMedia legend has much in common with traditional map legends, but it does much more. The legend controls which features are displayed and available for analysis. It allows you to control how features are displayed and to associate properties such as font, locatability, and titles with each feature class. Legend functionality extends beyond feature display to the display of queries, thematics, and images.
By default the GeoWorkspace application contains a blank legend, a blank map window, the coordinate system, and warehouse connections, if any have been saved. As discussed previously, the map window is empty until you add feature classes to the legend. In this exercise you will add parcels and the TIGER linework for roads and boundaries to a legend. Open a new GeoWorkspace. For this workflow, you need the parcels.mdb and tgr05143.mdb warehouses.
2. Add a feature class. On the Main Menu bar, click on Legend > Add Feature Class, or click on the Add Feature Class button, shown in the illustration at left.
3. Select a connection and a feature class. Click on the down arrow to view all connections. Select a connection, parcels, by clicking on it. Select the assessor_data feature class. Click on OK.
5. Run the Legend > Add Feature Class dialog again and select another connection and a feature class. Hold down the Control key to select multiple features. Use the Shift key to select items adjacent to one another in any list.
6. Name the GeoWorkspace, and then save it. Navigate to your geoworkspace directory and type parcels and tiger for the file name, and click on Save. Alternatively, on the Main Menu bar click on File > Save GeoWorkspace As. . The completed workflow is shown in the illustration that follows.
NOTE:
Saving the workspace stores a copy of your projection, connections, feature
classes, and legend entries. Saving the workspace also allows you to resume
work where you left off. However, many active legend entries will slow
down opening the workspace. Exiting without saving will leave your workspace
with the configuration it had when you began your GeoMedia session. You
will be prompted to confirm that you do not wish to save.
When you finish with the Save GeoWorkspace
As dialog, the workspace is changed to the new name. If your map window
is maximized, you may not be aware that this has happened. When the map
window is maximized, the map window title replaces the usual main title
reference to the GeoWorkspace name. This is a bit confusing, so try it
yourself. Click on the maximize button on the map window title bar. Note
that parcels and tiger.gws have been replaced with [MapWindow1]. Workflow
8-1, "Managing the Display Environment," covers handling windows in detail.
Legend Content
This section provides an overview of the display and behavior information portrayed in the GeoMedia legend. The legend contains an entry for each feature class, query, thematic, or image you add. The legend contains a wide range of information about the current state of objects in the map window, behavior associated with map objects, and the display characteristics for each one.
Note: The information and interactive controls contained in the legend are duplicated, in a different format, on the Entries tab of the Legend > Properties dialog. As is often the case in GeoMedia, there are several alternative paths to any given set of commands. With legends, you access the commands within the legend from a pop-up menu in the legend or the map window. The Legend Properties dialog runs from the Main Menu bar, the Legend toolbar, or from within the legend. Manipulating legend entries from the Legend Properties dialog is discussed later in this chapter.
The various aspects of legend functionality and symbology are discussed in reference to the application window shown in the following illustration. Please note that not every item for which there is a legend entry is visible in the map window. For easier visualization, only a portion of the entire data set represented in the legend is shown in a zoomed view in the illustration.
ORIGINAL GRAPHIC ig090002
Locatability
The leftmost symbol, a northwest arrow, associated with a legend entry indicates that the map objects in that feature class are locatable. When locatability is turned on for a feature class you can double click on a map object in the map window and GeoMedia makes the object a member of a select set. When an object is selected the database record associated with the map object can be retrieved and the object’s attribute data can be displayed, or the object can be edited.
The ability to control locatability is convenient when you are working with densely clustered graphic data. If you need attribute data for a particular feature class, turning locatability off for all other classes makes selection of the map objects, retrieval of attribute data, and editing geometry much easier.
For example, suppose you were working on a project that required you to locate individual water valves. You might need water lines, streets, parcels, and other types of data displayed so that you could easily navigate around the map. However, you only need attribute information about valves. Disabling locatability for all features except valves narrows the number of selectable objects to that feature class and the data associated it.
In the legend in the previous illustration, all entries are locatable, with the exception of CountyBoundary. Conversely, although locatability would appear to be specified for Airport by NAME, in this context it is meaningless. This is a legend entry for a thematic display. A thematic display is constructed from the attribute values for all features in the feature class, but it does not exist as records in the database. Because no attribute data exists for this legend entry, none can be retrieved beyond that contained in the feature class from which it is derived. See Chapter 22 for details on thematic displays.
Display by Scale
A small scale bar in the leftmost position in a legend entry, alone or in combination with the locatability arrow, indicates that the entry is set to Display by Scale. Display by Scale allows you to define a limiting scale range within which the map object will be visible. Display by Scale is useful for controlling the display of map objects, like labels or city streets, that become illegible above or below a given scale range.
When a map object is set to Display by Scale, the display of that feature class is dynamically toggled on and off as a function of the map window scale. Thus, when you zoom in and/or out on a map view, display of a feature such as a text label will be activated. It is possible to set both upper and lower limits for the display. The details of using the scale are presented later in this chapter.
In the legend shown in the previous
illustration, the Institutions feature class is set to Display by
Scale. The scale parameters have been specified such that when the map
window display is zoomed out in excess of 1:1000000, the Institutions
feature class display is turned off.
Graphics Density Relationship to Display Priority, Locatability, and Display by Scale
Turning on the Streets display in the sample legend makes the map difficult to read. This is an example of dense graphics. At the present zoom scale, about 1:685,000, the street features are virtually indistinguishable from one another and they are obscuring the view of other map objects. See the following illustration.
Caption: Example of dense graphics.
Displaying a feature class of this size (22,681 elements) seriously slows down all operations that require repainting the map window. This suggests that the feature class is a good candidate for further map window "fine tuning." The following are measures that could be taken to tune the map window.
The feature class display priority can be lowered by moving it to the bottom of the legend, allowing you to see the other feature classes. However, this will not improve map window performance.
You could set Streets to Display by Scale. This would inhibit the display of the features unless the map window is zoomed in to a scale range in which the streets can intelligibly display.
Consider the issue of locatability. Locatability, discussed in material above, refers to the ability to interactively find a map object, select it, and display its associated database attributes. When graphics are packed, as the streets are at this scale, it is almost impossible to locate the individual streets or distinguish them from other feature classes in the map window.
If your workflow requires that you see
the line work for the streets, but you are not particularly interested
in their individual attribute values, it may be worth considering turning
their locatability off. Turning the locatability of dense graphics off
when it is not required forces the selection process to simply ignore those
graphics. This makes it much easier for you to ide.gify and select map
objects from those in whose attribute values you are interested. Setting
Display by Scale and Scale range are discussed below in Working with the
Legend Properties Entries tab.
Style Key
The graphical representation of the map object, the Style Key, tells you what type of map object the entry represents. If the legend entry is a feature class, the Style Key indicates the geometry type. The Style Keys for geometry include Point, Line, Area, Compound, and Text. The definitions of these geometries are mostly what you would expect, though compound may be confusing. Compound is the term used for feature classes that include two or more types of elemental geometry. Common examples are area features that include a centroid (a point) to which attributes are associated. This area and centroid data type is a common one in many CAD data structures.
In a single GeoMedia display, there might be an area feature (such as soils) from an ArcView warehouse that consists of areas with associated attributes. These would be features with area geometry. In the same map, there could be a different feature class, say lakes, that was a MicroStation-derived area feature with centroids. These would be compound features. If the legend entry is a query, the Style Key is represents the geometry of the feature class on which the query is based. Thematic unique, thematic range, and images each have their own Style Keys.
In the previous illustration, the Institutions, Highways, Railroads, Airport, CountyBoundary, assessor_data, and tract_label are legend entries representing different feature classes. The Style Keys associated with these entries indicate that the Institutions feature class consists of point data. Highways and Railroads are linear geometry. Airport and CountyBoundary consist of area geometry. The Style Key for assessor_data indicates that it contains compound geometry. The tract_label legend entry represents the final type of feature class data, text.
Airport by NAME illustrates the Style Key for a unique thematic display. MajorWaterPolygons by AREA is a thematic range display. Its Style Key is very similar to the unique thematic Style Key.
Airports 1 mile from Highways is a legend entry for a query. The Style Key for a query is the same as that of the Airports feature class geometry. The final Style Key available for a legend entry is the one representing imagery. In the sample legend in the previous illustration, it is associated with the gm_logo.gif entry.
This leaves you with three mystery legend entries. Although you can probably guess, you cannot tell from the legend the geometry types of tiger_rail, Streets, or AI_sections features. These symbols for these legend entries graphically indicate bad warehouse connection status. The meanings of these types of legend entries are discussed in the "Working with the Legend Properties Tab" below.
The Style Key is not only a static icon representing the legend entry type; it is also a shortcut to the Style dialog. Double clicking on the Style Key for any legend entry takes you directly to the Style dialog for that entry. This dialog is discussed in chapter 12.
Legend Entry Title
The legend entry title defaults to the feature class name or the query name for features and queries. In the case of thematic displays, the legend entry is a combination of the feature class name and attribute name on which the thematic is based. Image titles are entered in the legend with their file system name. As discussed later in this chapter, it is possible for you to define a new name for each legend entry. Meaningful titles are an important consideration when you are creating cartographic output from your map window displays.
Legend Statistics
The number in parentheses following the title is called the statistic. It represents the number of instances, or the number of records, that reside in each displayed feature class. This feature is particularly useful in cases in which you have added a feature class to the legend but cannot see it in the map window. The first step in troubleshooting this situation is to confirm that the class does indeed contain features, by turning on the View Statistics legend option. There are a couple situations when a feature class with no records is added to the legend. First, perhaps there is a spatial filter on the warehouse connection you are using and none of the features in the selected class fall within the filter. Adding the feature class will result in the creation of a new legend entry with a feature count of zero.
It is also possible for a graphic feature class table to exist that contains no records. This occurs in cases in which, for example, the Feature Class Definition process has been used to set up the class but the features have not yet been digitized. Whether the new table contains records or not, it is a valid feature class and will appear as a selection in any dialog that accesses the feature tables in Access connections. This idea also pertains to other types of data servers. The bottom line is that feature classes can be valid entities that contain no feature data.
Legend Properties
When a legend entry is created for a map object, its graphics are added to the map window. In this segment of the chapter you will be introduced to some of the display parameters managed through Legend Properties.
Legend Properties can be divided into two general sections. First are the parameters that control the display style of feature classes in the map window and the content of the entries within the legend. Second are the settings that customize the appearance of the legend. Whether you want to change display symbology, legend entry appearance, or the overall appearance of the legend, the necessary functionality is contained in a series of dialogs available in Legend Properties.
There are two ways to access the Legend Properties dialogs. From the Main Menu bar you can select Legends > Properties or click on the Legend Properties icon on the Legend toolbar. A right mouse click in the map window produces a pop-up menu that contains the Legend Properties command.
The Legend Properties dialog is divided
into two tabs: General and Entries. The General tab allows you to control
the overall appearance of the legend. The functionality contained on the
Entries tab allows you to define how each entry looks in the legend and
how its associated geometry is displayed in the map window.
General Tab
The General tab, shown in the following illustration, allows you to control the way the legend itself is displayed. Background color, title bar, and autofit are properties of the legend. The font settings, statistics, and tooltips describe universal display properties for the legend entries. These properties apply to every entry that the legend contains.
ORIGINAL GRAPHIC ig090004
This contrasts with the settings that are customizable on the Entries tab, where you specify exactly what is displayed for each legend entry. So while you change the title for a legend entry on the Entries tab (for example, you change the assessor_data title so that it displays in the legend as Parcel IDs), the settings on the General tab determine the font settings used to display the legend entry.
Legend Fonts
The General tab allows you to set the various fonts for each category of text: legend title, subtitle, and headings. The sample legend illustrated in the previous section consists of titles and headings only. Headings are the entries that fall under the thematic display entries. There are no subtitles in the sample, but they can be added to the legend from the dialog on the Entries tab, as you will discover in material to follow.
The Font dialog you access here is a standard Microsoft font dialog. It is accessed by clicking on the appropriate category button in the Font section of the dialog. It allows you to specify font type, such as Arial, Courier, and so on; font style, such as Bold or Italics; and font size. Through this dialog you are given the option for two effects. Legend entries can be displayed with an Underline and/or a Strikeout. You can change the color of the text for the legend entries. A preview of these settings is displayed in the sample box associated with each of the buttons.
Legend Background Color
The Background Color button gives you access to a color table from which you can select a color for the legend background. It defaults to white.
Legend Display Options
The checkbox section allows you to set the default display to on or off for the four options presented. Show tooltips displays the complete legend title for titles that are truncated due to the size of the legend window. When the cursor is paused over a legend entry, the entire title is displayed. In certain cases, what is displayed when the cursor is paused will be a prompt indicating the type of action that will ensue if the item is double clicked.
Show statistics allows the legend to add record counts for each legend entry, as discussed in the previous section. Show title bar specifies whether the legend title bar is on or off. When Autofit legend is selected, the legend window is automatically resized to fit all legend entries. If you prefer to manually size the legend window, leave the box unchecked. The Legend window can also be fitted to the entry length with the Legend > Fit Legend command or from the pop-up menu in the map window. The area in the lower right of the Legend Properties dialog labeled Example layout display is not dynamic. It simply shows you the structure of the text layout for the legend.
Entries Tab
The dialogs attached to the Entries tab give you access to both the contents of the legend and to the display symbology for the graphics that belong to each entry. In other words, the Entries tab allows you to control the appearance of objects in the map window and the way they are represented in the legend.
Working with the Legend Properties Entries Tab
Earlier sections of this chapter provided you with a broad overview of the legend and its role in constructing and maintaining map objects in the GeoMedia map window. With the legend tools, you customize map objects to facilitate the analytic requirements of your workflow. That is, you control which objects are displayed, how they are displayed, how they behave at various scale settings, and whether they are "connected" to their nongraphic attributes through locatability. The map window and legend are important components of cartographic hardcopy output. Although overall map composition occurs in the Layout window, the design of the legend and the contents of the map window are transferred directly to the Layout window.
In this part of the chapter you will review how the legend commands are used to control both the content of the map window and the appearance of that content. Remember, each map window and its legend are separate and distinct from all other open map windows. This feature allows you to specify different legend properties and legend entry properties for each window. For example, the same Streets feature may be displayed in two map windows. Because the map windows and legends are independent of one another, different display symbology can be applied to that feature class in each display.
The interactive control of the appearance and behavior of graphics in the map window occurs at the legend entry level. This section of the chapter attempts to follow the same outline of legend entry functionality presented in earlier sections. In this part of the chapter, you will be provided with specific detailed procedures, techniques, and tips for controlling the display properties and behavior of map objects by legend entry manipulation. This begins with a review those parameters with reference to the same application window you saw earlier.
The following illustration shows the sample GeoMedia application window again.
ORIGINAL GRAPHIC ig130001
The Elements of Legend Properties Entries Tab
The GeoMedia legend contains an entry for each map entity added to the map window. Each legend entry contains information about the current state of the entry, its geometry (if any), its title and subtitle, its behavior regarding display scale and locatability, and its display symbology.
These elements are controlled on an entry-by-entry basis on the Entries tab of the Legend Properties dialog. As always there are several ways to access the Legend Properties dialog. From the Main Menu bar, you can click on Legend and select Properties from the drop-down menu. A right mouse click in the map window produces a pop-up menu (shown in the following illustration) from which Legend Properties can be selected. Finally, double clicking on a legend entry not only takes you directly to the Entries tab but selects that legend entry for editing on the Entries tab.
Replace graphic with hgm11_3.gif
The dialogs attached to the Entries tab give you access to both the content of the legend and to the display symbology for the graphics that belong to each entry. Therefore, the Entries dialogs allow you to control the appearance of objects in the map window and how they are represented in the legend.
As shown in the following illustration, the Entries tab contains a row that describes the legend properties for each entry in the legend. Each column in the dialog represents one of the entry elements. The entry elements presented here are simply in a slightly different format than that of the actual legend entry as it appears in the legend window.
ORIGINAL GRAPHIC ig130003
Entries Tab Navigation
Clicking in any cell of the Entries tab makes it available for editing, whether it contains a toggle, text, or has a drop-down menu associated with it. Clicking on the selector button at the far left of an entry highlights the entire record, allowing you to modify or delete the entry. Clicking on the top, leftmost button selects all legend entries. Clicking on the Delete button with all entries selected effectively clears the legend and the map window. You can also modify the Display by Scale parameters for all legend entries at one time by selecting all the records on this tab.
Take a look at each column for the legend
entries in the previous illustration. The sections that follow discuss
each column in detail.
Style Column
The graphical representation of the map object, the Style Key, tells you what type of map object the entry represents. The bitmap that appears in the Style column is the same Style Key that appears in the legend. If the legend entry is a feature class, the Style Key indicates the geometry of the class.
This is a display-only field that cannot
be manipulated. The exception is Style Keys that represent legend entry
state information for closed connections, invalid data, and unloaded data.
These keys will change when steps are taken to resolve the problem that
caused the bad state. The following section explains what causes invalid
states and how these states can be resolved.
Legend Entry State
State information is generated by some event, relative to either a connection or the data itself, which has rendered a feature inaccessible. When this is the case, state symbology appears in place of the Style Key, which tells you that something has gone wrong during the loading process for that entry.
Most, but not all, legend entry state problems can be resolved by editing the warehouse connection. However, none of the options normally available in the Legend Properties dialog are available unless the legend entry’s state is returned to normal.
Data Not Loaded
The first legend entry state is "Data is not loaded". The legend symbol is a circle with a diagonal cross bar. The "Data is not loaded" state can result from several sets of circumstances. When you add a map object, then interrupt loading by pushing the Escape key before the map window is updated, a legend entry will be created, but its state is set to "Data is not loaded." If the warehouse and the connection are still valid, correcting a "Data is not loaded" is simply a matter of going to the Legend Properties dialog and turning on the display of the particular feature class. Turning the class display on will force GeoMedia to reload the data from the warehouse.
A "Data is not loaded" state can also happen when the display of a legend entry is turned off and the workspace saved. When the workspace is subsequently reopened, that entry’s state is set to "Data is not loaded." The same thing happens when you replace the current legend with a named legend that contains an entry whose display is turned off.
Finally, a legend entry will be in the not loaded state if you have set selected the Do not load data when opening GeoWorkspace option on the General tab of the Tools > Options dialog.
In the legend shown in the previous illustration,
the "Data is not loaded" symbol is attached to the Streets entry.
The steps that led to this state are as follows. The Streets feature
class was added to the legend. The display of Streets was turned
off, but the entry was left in the legend. This is indicated by the fact
that the entry is dimmed in the legend. The ability to turn off a feature
class display is a useful tool that allows you to temporarily clean up
the map window without having to physically delete items from the legend.
The workspace was saved with this entry’s display disabled. The change
to the "Data is not loaded" state occurred the next time the workspace
was opened.
Fixing the Data Not Loaded State
Replace graphic with hgm11_2.gif
In this example, the warehouse and the warehouse connection are still valid. This is confirmed by the fact that other feature classes in this connection, such as Institutions and Highways, are in a normal state. Therefore the problem lies exclusively with the Streets feature class. It can be resolved by running the Legend > Legend Properties dialog and turning the Streets Display field on, forcing GeoMedia to reload the feature class. This situation can be remedied directly within the legend. A right mouse click on the Streets legend entry produces a pop-up menu specific to the Streets entry. This menu is discussed in detail later, but for the time being look at the selections shown in the illustration at left. Dimmed menu selections are not available. For example, Display Off is not a valid selection because the entry is already turned off. Collapse Legend Entry applies only to thematic displays and is likewise unavailable.
Display On and Display Off control whether or not the feature class appears in the map window. Clicking on Display On toggles the Street feature’s display and fixes the "not loaded" state of this legend entry. (See the following illustration.) The other option in this menu is the Load Data command. In this situation is produces the same results as the Display On command. Notice that the Style Key for Streets now properly reflects the fact that this feature class consists of linear geometry.
ORIGINAL GRAPHIC ig130005
Resolving the "Data is not loaded" entry state.
Connection Closed
The second legend entry state is "Connection is closed," whose symbol is a red X over the connection icon. There are two common causes for this state. The first is a result of editing a warehouse connection and changing its status from open read/write or open read-only to closed. Feature classes added to the legend before this change will be flagged as "Connection is closed."
The second scenario that will generate
a "Connection is closed" state involves a change in a warehouse location
in the file system. The path to your warehouse location is built when you
create a new connection, and this information is stored in the GeoWorkspace
when you save it. If the warehouse is subsequently moved to a different
location in the file system, the path information becomes invalid and GeoMedia
will be unable to find the warehouse. When the workspace is reopened, if
you elect not to correct the path information, the connection fails and
any feature class in that warehouse that had a legend entry is marked "Connection
is closed."
Fixing the Connection Closed State
In the sample legend, the legend entry for tiger_rail is posted with the Connection Closed symbol. The warehouse connection for the tiger_rail entry was closed after the feature class was added to the legend through the Warehouse > Edit Connection dialog. The fix for this state is made entirely outside legend. From the Main Menu bar click on Warehouse > Edit Connection. The situation is remedied by setting the connection status back to either open read-only or open read/write.
If this state resulted because a warehouse location changed, you will have to edit the connection, correct the path to the warehouse and then open the connection. Warehouse connections are discussed in detail in Chapters 6 and 39. The Edit Connections dialog is shown in the following illustration.
ORIGINAL GRAPHIC ig130006
The tiger_rail feature class resides in the tgr05143 warehouse linked to the GeoWorkspace with the tiger connection. That connection is closed and simply needs to be opened to resolve this state problem. Remember that you can determine the connection associated with a feature using the Legend Properties dialog box. The Source panel in the lower left indicates the connection associated with the selected feature class.
Note: Query sources are not shown on Legend Properties Entries tab. The source connection for a query can be found using the Analysis > Queries dialog. The Edit button will provide you with the connection information you need.
Clicking in the Status cell for the tiger connection produces a drop-down arrow. Clicking on the arrow produces a spin box that contains selections for closed, open read-only, and open read/write. Selecting either of the open selections results in the restoration of the tiger_rail legend entry to a normal state. Opening a closed connection is shown in the illustration at left.
ORIGINAL GRAPHIC ig130007
Invalid State
The final condition that can be indicated in the legend is "Legend entry is in an invalid state". The legend symbol is a diamond in a square with an exclamation point in the center. Map objects displayed in the map window are dynamically linked to their attribute data in the source warehouse. Changes made to the attribute data associated with a map object from a read/write warehouse trigger an immediate update to the display of those objects in the map window. The state of a legend entry becomes invalid when the geometry column or an attribute value is changed in such a way as to render the map object undisplayable.
When you attempt to open a GeoWorkspace that contains a legend entry that is in an invalid state you are presented with a warning dialog. This dialog prompts you to determine whether or not to continue loading legend entries. The More button on this dialog box provides a description of the cause of the entry’s invalid state. If, by selecting Yes, you indicate that you want to continue loading, even though there is a problem, GeoMedia continues loading entries, in which case the invalid entry is simply flagged in the legend.
When you select No to stop loading entries, the legend will contain
only the entries processed before the invalid entry was encountered. Because
the legend entries are loaded from the top of the legend down, all entries
following the one in an invalid state are ignored when this option is selected.
This state, as reflected in the legend entry for AI_sections, may
be irrecoverable. Because it is the result of database deletions or modifications,
fixes will have to occur in the database.
Fixing an Invalid State
The legend entry for AI_sections indicates that it is in an invalid state (a diamond with a red exclamation point), which is the result of data corruption. Fixes for this state are dependent on the chain of events that led to the data corruption. Something has happened to either the geometry column for this feature class table or to another attribute in this database that makes it impossible for GeoMedia to display the graphics. The most likely cause is the corruption of the geometry column in the feature table.
The fix for this condition depends on what got changed and how it got
changed. Often the only recourse is to restore the database from a backup
copy.
Title Column
The Title column contains, by default, the name of the feature class, query, or thematic. Image titles are represented in the legend by their file name. The Title column content can be changed by clicking in the cell that contains a title you want to change and typing in a new name. This has no affect on the feature class name stored in the data warehouse. It changes only the text that represents the map object in the legend.
Note: True connection and feature class names are displayed in the Source panel of the Entries tab.
Subtitle Column
The Subtitle column is blank by default. This field provides you with an opportunity to add text to a legend entry. It has no affect on source data and may make your legends more understandable.
Display Column
The content of the Display column indicates the display status of each entry in the map window. When you click in a cell in this column, the cell highlights and the down arrow appears. The options available from the drop-down menu are On, Off, and By Scale. As you saw in the section above fixing "data not loaded" state, the Display Off, Display On, and Display by Scale settings can also be accessed through the pop-up menu in the legend.
Display Off
The Off option removes a legend entry’s graphics from the map window. The entry remains part of the legend, but it is dimmed to indicate that its display is turned off. An example of this is shown in the illustration at left.
In the legend in the previous illustration, Streets and MajorWaterPolygons by AREA have their map window displays suppressed. Remember, if this workspace is saved as is the legend entry's whose display is off will be set to the data not loaded state when the workspace is reopened. To reload the data, toggle the legend entry for the feature to the displayed status. This will cause the data to be reloaded.
Display by Scale
Display by Scale is a useful option for managing map objects whose visibility is obscured when viewed at certain scales. Suppose your map window contains a statewide county coverage labeled with county names. When you execute a Fit All command for the map window, the text labels are likely to appear to overlap one another. When you zoom out further, they seem to disappear from the display altogether. However, as you zoom into the map window, they become distinct and legible.
This type of feature is a good choice for the Display by Scale option in legend properties. When Display by Scale is selected for a legend entry, the map objects are displayed only when the view scale of the map window falls within the scale range you have specified.
Displaying the Map Window Zoom Scale
The map view scale is displayed in the rightmost panel of the GeoMedia application window if you have specified it in the Tools > Options dialog. The General tab of this dialog allows you to enable the status bar display and to select either view extents (linear window measurements) or the zoom scale display on the status bar. Enabling zoom scale display can help you determine by trial and error what the appropriate custom scale range for your map objects should be.
The Institutions legend entry in the sample legend is set to Display by Scale, as indicated by the scale bar in the leftmost position for the entry. When the scale of the map window exceeds 1:1,000,000, the Institutions features are removed from the map window and the legend entry is dimmed.
Scale Range
Display by Scale has a two-part setup. In the first part of the setup, you specify that the legend entry is scalable by setting the Display by Scale option in the Display column. You then select the appropriate range from the Scale Range dialog (shown in the illustration at left) associated with the Scale button at the bottom of the Entries tab. The Scale Range dialog provides you with eight predefined ranges associated with each of the icons in the dialog.
• 1:30,000,000 to 1:110,000,000
• 1:10,000,000 to 1:45,000,000
• 1:900,000 to 1:16,000,000
• 1:200,000 to 1:2,000,000
• 1:5,000 to 1:400,000
• 1:100 to 1:15,000
• 1:1 to 1:300
Workflow 11-2:
Using Legend Properties to Set Scale
As you have seen, Legend Properties controls the way in which map graphics are displayed. In this workflow you will learn how use the Display by Scale feature. Features set to display by scale are turned on in the map window only when the display scale falls within a specified scale range. When you zoom to a scale outside the range, the graphics are turned off.
In this exercise you will configure the hydro_name label feature to display only when you are zoomed into the map window, shown in the following illustration. Make sure you have the tiger.mdb warehouse in your warehouses directory. Open a new GeoWorkspace and connect to the tiger warehouse. Add the feature classes tiger_boundary, tiger_hydrographic, and hydro_name to the legend.
ig130009a
At this display scale, the label feature, hydro_name, is illegible and represents little more than noise on the map. By setting the Display By Scale parameters, you are able to control the threshold at which they will be turned on in the map window.
The scale of the map window is displayed on the Status bar in the lower right-hand corner of the window (see the following illustration). It always reflects the scale of the current display, and is updated each time you zoom in or out. If your map window includes a scale bar, it too is rescaled when the display is changed. Zooming in on the map, you see that the labels become legible at about a 1:63000 scale.
The map window is updated with the new scaling information and the display is refreshed, as shown in the first of the following illustrations. A scale bar is added to the legend entry for hydro_name to indicate that it is a Display by Scale feature. When zoomed out to the original map display scale, the label feature is not shown, as indicated in the second of the following illustrations.
ORIGINAL GRAPHIC ig130009f
ORIGINAL GRAPHIC ig130009g
Locatability Column
Locatability was briefly touched on in the previous discussion of dense graphics. The information stored in your feature class tables will most often, though not always, consist of both graphic data (stored in the geometry column of the table) and many nongraphic attributes associated with that geometry.
Feature Classes and Queries
Each record in a parcel feature class might contain the line work (spatial information) for the graphic display of the parcel map. It probably also contains all types of attribute (nonspatial) information about each parcel, such as its parcel ID number, its assessed value, area and perimeter dimensions, and the owner’s name and address. When a map object is designated as locatable, the link between the graphic and its associated attribute record is activated, allowing you to interactively view the attribute data by selecting the object of interest in the map window.
These concepts apply to locatable query legend entries as well as feature classes. Queries do not exist as records in database tables. However, just as the legend Style Key for queries is based on the geometry underlying the query, locatable queries will report the attribute values associated with the feature class on which they are based.
The selection in the Locatable column is a toggle. Clicking in a cell in this column sets the cell’s value to the opposite condition. If it was locatable, clicking on the cell would make it not locatable, and vice versa.
The following illustration shows an example of the data display that results when a locatable map object is double clicked. The Attributes tab contains the attribute data associated with a segment of the highway feature class. This segment is located about midway on the right-hand side of the map display. Clicking on it returns all of the attribute values contained in the database record for that map object.
ORIGINAL GRAPHIC ig090010.
The listing on the left contains all column headings for this database record, and the column on the right contains the values for each column. Although it will be discussed in more detail in Chapter 815, it is worth noting here that because this feature is part of a read/write warehouse connection, the attribute values in the right-hand column are editable. They can be changed by selecting the cell and typing in a new value.
Similarly, the illustration at left shows the attribute data available via the General tab of the same dialog. The information contained on the General tab is primarily metadata pertaining to the feature class. The Length field, or Area field for polygon geometry, displays the dimension of the selected map object. The units of measurement are those specified on the Measurement Units and Format tab of the Tools > Options dialog.
There are some points you should consider when deciding if a legend entry needs to be locatable. You have looked at the relationship between graphic and nongraphic attributes and how they are accessed with the Locate tool. However, what if there are no attributes associated with a feature class? Remember, there is no requirement that a feature class contain records, and there is no requirement that a map object have any attributes beyond a geometry field and a Key field.
Perhaps the feature class records do contain attribute columns, but they are irrelevant to your current workflow. In this situation, there is no need to have locatability enabled. In fact, it may only make it more difficult for you to isolate the map objects in whose attributes you are interested.
Imagery
Legend entries for imagery present an interesting contrast to the foregoing emphasis on the relationship between map objects and attribute data. Imagery, by definition, is not associated with attributes in a database table. Imagery warehouses simply contain the path information that points to the location of the imagery files in the file system. This makes the Attributes tab unavailable for imagery. However, although you may not have a routine need to view the Properties tabs for imagery, the General tab does contain some interesting metadata about the images.
The illustration at left shows the General tab, containing information about the gm_logo.gif raster legend entry, including file type, format, connection name, image size, number of lines, and pixels per line.
ORIGINAL GRAPHIC ig130012
Thematic Displays
Like images, thematics do not exist as records in database tables and therefore have no associated attribute values. Unlike images—although locatability is enabled by default—thematics are never available for select set membership. Locatability in reference to thematics is therefore a moot issue. It neither helps nor hinders your workflow, whether it is enabled or not.
Preview of Locatability and Select Sets
The material covered in the current section has been restricted to a discussion of the active link between graphics and attributes that locatability provides. In actuality, there is a large suite of functionality available for map objects defined as locatable. In spite of what has just been said about locatability with reference respect to attribute data, this functionality is not restricted to feature classes that contain attribute data.
Technically, locatability is the characteristic that determines whether a map object can become a member of a select set. If the feature is locatable and resides in a read/write warehouse, membership in a select set designates the map object as input for graphic editing commands, attribute editing commands, and many other operations that modify data. This aspect of locatability and the functionality associated with Select Set membership is discussed in detail in Chapter 15.
Entry Column
The Entry column is used to determine whether
a given legend entry appears on the legend. When this field is unchecked,
the legend entry is suppressed, but the display of objects in the map window
is not. This feature allows you to shorten a long legend while preserving
the content of the map window. The downside of removing an entry from the
legend is that you no longer have access to the interactive functions GeoMedia
provides for legend entries, which is discussed in material to follow.
On the other hand, a legend entry can be reestablished at any time through
the Legend > Properties dialog. The Entry column contains toggles. Clicking
in that column for a selected legend entry reverses the status of the field
value.
Legend Style
The Style button takes you to one of four
dialogs that allow you to define the display symbology and map view properties
for feature classes, text, queries, thematic displays, and images. Working
with Styles is covered in Chapter 12.
Controlling Legend Entries
Some settings apply to individual components of legend entries; others are associated with a legend entry as a whole. This functionality is contained in the Delete, Style, and Priority dialogs. To access these dialogs, select an entry by clicking on the button to the left of the entry and then clicking on the desired command.
Deleting Legend Entries
When you select an entry and click on Delete, that entry is immediately removed from the display in the Legend Properties dialog. There are no options associated with the Delete command. Further, the usual Confirm Deletion warning does not appear, even when Confirm Delete is set to Yes on the General tab of the Options dialog (see Chapter 7 10 for more information on Options). However, the action is not executed until you click on OK or Apply. This gives you the opportunity to recover from an unintended deletion by abandoning the dialog with the Cancel button.
Changing Display Priority
The Priority button allows you to reposition an entry in the legend. The order in which entries appear in the legend is an important aspect of map window management. Note that the entries in the Legend Properties dialog appear in the same order they have in the legend. This order is referred to as display priority. The entry at the bottom of the legend is placed in the map window first. Subsequent entries are added to the map window as you move from the bottom of the legend to the top. The entry at the top of the legend is on the top of the map. It is drawn over entries that are lower than it in the legend.
This entry priority has the potential to obscure the display of the objects it overlays. A park, for example, might obscure the streets that pass through it. To remedy this situation, you need only adjust the priority of an entry by clicking on the Priority controls to move it to a more desirable location in the legend. You can also change these priorities on the legend by simply selecting and dragging the entry to its new position on the legend and map.
The maps in the two illustrations that follow demonstrate the result of changing display priority. In the first illustration, Institutions is placed in the map window first. When Airport by NAME is added, shown in the second illustration, it obscures some of the Institutions features.
ORIGINAL GRAPHIC ig090007
ORIGINAL GRAPHIC ig090008
To verify that you can see all Institutions and Airport by NAME features, select Institutions and click on the up arrow above "Priority" on the right side of the dialog. Everything in the map window will then be visible.
Adding Legend Entries
The Add button contains a drop-down menu. The menu consists of the same Add functionality for feature classes, queries, thematic displays, and images as the Legends menu on the Main Menu bar discussed at the beginning of this chapter. If you want to add new entries to the legend while changing properties of existing ones, you do not have to go back to the Main Menu but can simply click on the Add button. Once you have added a new legend entry, you can also immediately customize it using the open legend properties dialog options.
Source Information
The Source field is a read-only field that provides very useful information about legend entries. This information is provided regardless of the state an entry is in. In other words, even if there is a problem with the status of a legend entry, the Source field still provides information. The information contained in this field varies as a function of the type of legend entry selected.
In the case of feature classes and thematics, the feature class name is shown prefixed with the connection name in the format connection.feature name. This can be valuable in two different situations. First is the case in which the same feature class name exists in different warehouse connections. For example, say you have an MGE project connection that contains a feature called Airport, and an Access warehouse that contains a feature class named Airport. In the legend itself it is impossible to distinguish which warehouse is the source for each of the Airport feature classes, but the source field provides that information. This allows you to optionally title each legend entry in a way that distinguishes the warehouse to which it belongs.
The second case is the inverse of the one just described. Say you have already changed the titles for your legend entries such that you are no longer certain of their source feature classes. The information in the Source field will display the original feature class name when you select a legend entry.
When the legend entry selected is a query,
the saved name of the query is displayed. In the case of imagery, the Source
field displays the connection name (as the prefix) and the name of the
table where the path to the image is stored.
Manipulating Legend Entry Properties Within the Legend Window
Replace graphic with hgm11_3.gif
Selecting an individual legend entry and clicking the right mouse button produces a pop-up menu containing many of the Legend Properties commands. However, in this case their functionality is slightly different in focus. Right clicking on a legend entry is the functional equivalent of selecting the entry from the Entries tab of the Legend Properties dialog, shown in the illustration at left. It therefore establishes that particular entry as the subject for all subsequent modifications. This provides you with a shortcut to Properties commands for the specific legend entry in which you are interested. The actual functionality of the commands is identical to that described in the previous sections.
The selections in the top two sections of the menu are toggles. When you click on them, their states are reversed. You see that the menu contains the three Display options: On, Off, and By Scale. Display On is not available in the previous illustration because this legend entry is currently in the On state.
The Locatable selection is the equivalent of the Locatability column in the Legend Entries dialog and turns locatability on or off for the selected legend entry. Hide Legend Entry is the same as the Entry column in the Properties dialog, which turns off the display of the entry in the legend without affecting the display of the objects in the map window. Load Data is an alternate command for Display On.
Collapse Legend Entry is a command you have not seen before. It is discussed in Chapter 622. It is relevant to thematic displays only, which is why it appears as a dimmed selection in the previous illustration. In a thematic entry, there will be one or more categories listed under the legend entry.
For example, category 1 in a demographic map might be residents with ages between 1 and 10 years, category 2 might be ages 11 to 20, and so on. Normally details about each category in the thematic map are shown in the legend under the map’s name. Putting a check in Collapse Legend Entry (by clicking on the box) will remove these category labels and show just the thematic map name. If you checked the Collapse Legend Entry selection for the Airport by NAME entry, the three entries under it would be removed from the legend. This action has no affect on the thematic display in the map window, but it is a good tool for shortening long legend entries.
The Legend and Properties commands that appear on this menu do not have anything to do with the selected legend entry. They are included in this menu for convenience. Fit Legend is the same as the AutoFit setting on the General tab of the Legend Properties dialog, which simply resizes the legend window to fit all of the entries it contains. The Legend selection is used to suppress display of the legend window. Again, this has no effect on the map objects in the map window. It simply clears the legend from the map window. View > Legend on the Main Menu bar is used to redisplay the legend after it has been turned off. The right click pop-up menu in the map window also contains a legend on/off command.
The Properties selection is a shortcut alternative to the Legend > Properties menu on the Main Menu bar, and to the Legend Properties button in the toolbar area of the application window. Like those, it takes you to the Entries tab of the Legend Properties dialog.
There are other methods of interactively managing legend entries that fall outside the scope of the legend window pop-up menu. These are great time-saving shortcuts you will find yourself using frequently in the course of your workflows.
First, you are provided with direct access to the Style Definition and Title dialogs for a specific legend entry by clicking on that part of the legend. Double clicking on the Style Key takes you straight to the appropriate tab in the Style dialog, bypassing the two steps it takes to get you there in the standard dialog. Double clicking on the Title of a legend entry takes you to the Title field of the Entries tab for that feature.
The second shortcut is provided through drag-and-drop reprioritization of legend entries. Remember, display priority is determined by an entry’s position in the legend, the last entry being the "bottom" layer in the map window. Display priority can be changed by simply clicking and dragging a legend entry to a new position in the legend. A separator bar will appear to show you where the entry will be placed when the mouse button is released.
Third, there is an interactive equivalent for the Delete button on the Entries tab of the Legend Properties dialog. Highlighting a legend entry in the legend window and pressing the Del key on the keyboard removes the entry from the legend and its graphics from the map window.
Tooltips, and Deselecting Legend Entries
A variety of tooltips are provided when you pause the cursor over the various parts of legend entries. They inform you of the functionality associated with clicking on a particular entry or element of an entry. For example, pausing over a thematic display Style Key produces a prompt that says you can double click to edit unique values. Also, the tooltip of a feature class tells you that double clicking will take you to the style dialog. Additionally, pausing the cursor over legend entries that are not in a normal state provides you with a brief description of the cause of the invalid state.
To eliminate the highlight associated with
a selected legend entry, click on the entry while depressing the Control
key on the keyboard.
Legends and Hardcopy Output
The map window legend and its entries can be directly transferred to the Layout window for the production of cartographic hardcopy. When your workflow requires hardcopy output, it is worth considering your options with respect to legend design. The appearance of the legend can be customized via Legend Properties before you insert the legend into the Layout window. The legend can also be changed once you get it into the Layout window.
Insert Map Graphics in the Layout window copies the Style Keys, titles, subtitles, and headings from a named legend to its working sheet. In the process, each item in a legend entry becomes an individual object. This gives you greater flexibility in legend design than does the Legend Properties dialog. However, this flexibility comes with a price. When the sample legend shown in the previous illustration is placed in the Layout window, it is transformed into 42 distinct objects you can manipulate. The sample legend as it would appear in Imagineer the Layout window is shown in the following illustration.
ORIGINAL GRAPHIC ig090003
You may want or need to deal with legend design at this level of detail, or you may opt to complete most of your legend design activities with the Legend Properties dialog. The choice is a matter of individual preference and workflow requirements. Discussion of the Layout window at this point is presented here as a heads-up. Cartographic output is discussed in detail in Chapter 14.
One further note should be made as you consider legend design with respect to hardcopy output. Style keys can be manipulated in the Layout window. If you prefer that they not appear on your maps, they can be deleted. As you have seen they cannot be accessed in the Legend Properties dialog.
