GeoMedia –
A Whirlwind Tour
This chapter provides a broad overview of some of the basic features in GeoMedia in a workflow format and serves as an introduction to its capabilities. All of the topics discussed here are covered in detail in later chapters. The problem presented here involves developing a GeoMedia workflow to ide.gify the cities in the state of Louisiana that are capable of providing disaster relief to neighboring cities located in flood-prone areas.
To accomplish this goal, you will build buffers around the rivers to determine the possible extent of flooding. You will use spatial analysis to find cities that are located in the flood zone and to determine the areal extent of potential flooding. Creating buffers around cities that fall within the flood zone will allow you to find neighboring cities that are not in the flood zone that might provide disaster assistance. You will develop a base map of communication facilities that might be impacted by river floods by geocoding their locations. Finally, you will generate reports about impacted population, and produce hardcopy maps of the area.
It is suggested that you go through the sections and exercise steps in order, as the later sections build on earlier ones. The data set used in this workflow is USSampleData.mdb, which is delivered with GeoMedia. If changes have been made to your sample data, you might want to run the GeoMedia installation setup again from the original CD. This time, however, use the Custom installation and select only the Sample Data to obtain a new, clean copy of the database. There is an additional file, LouisianaTVTowers.csv, which you will need later in the workflow. It is available in the Harnessing GeoMedia data sets.
GeoWorkspaces
The first requirement of a new workflow is a GeoWorkspace. A GeoWorkspace is the area in which your work takes place. Technically, it is a file that stores information about your working environment. At a minimum, a GeoWorkspace contains an empty map window where you will eventually display features, images, and labels; an empty legend, which is the tool you use to add things to the map window; and the default coordinate system, Cylindrical Equirectangular. As your workflow develops, the workspace might contain several map windows, each displaying different feature classes, data windows containing attribute data for those features, a different projection, a North arrow, a scale bar, and so on.
When you start a new workflow, you will typically create a new GeoWorkspace from a template. You can store many GeoWorkspaces in your workspace directory; however, only one can be open at a time. When you are ready to quit GeoMedia, you have the option of saving the GeoWorkspace. By saving the workspace, you can resume working where you left off.
Create a GeoWorkspace
To begin, create a GeoWorkspace by performing the following steps.
2. If the Welcome to GeoMedia dialog box appears on the screen, select "Create New GeoWorkspace"
Select File > New GeoWorkspace from the Main Menu bar.
The new workspace will open. It is shown in the following
illustration.
Save the GeoWorkspace
Continue by saving the new GeoWorkspace. To do this, perform the following steps.
2. In the File Name field, type Flood Wworkspace.
3. Click on Save.
A warehouse is a source of geographic data. Warehouses, or data servers, defined for GeoMedia include Access, Arc/Info, ArcView, AutoCAD, FRAMME, ODBC Tabular, MapInfo, MGE, MGE Segment Manager, SQL Server, and Oracle. Most warehouses are read-only, meaning that you are not allowed to make changes to the data stored in them.
Access warehouses are the exception. They are read/write warehouses that allow you to modify, add, and delete data. You can create new Access warehouses and import data to Access from your read-only data servers. This allows you to set up read/write connections to that data. The warehouse for this workflow, USSampleData.mdb, is an Access database.
Each warehouse is linked to your GeoWorkspace via a connection. A connection contains the file system path to your warehouses, as well as information about the connection type; that is, whether it is read-only, read/write, or closed. It can optionally contain a spatial filter. Each workspace can have connections to many warehouses, and the warehouse connections can be any combination of read-only and read/write.
Creating a Warehouse Connection
To create a warehouse connection, perform the following steps.
[Fig. 4
3. In the "Connection name" field, type US Data.
4. Click on Browse and navigate to the Warehouses directory. Select USSampleData.mdb and click on Open. Click on Next. See the previous illustration.
5. Select "Access all features in the warehouse" and click on Next.
6. Select "Let the wizard open the connection as read-only" and click on Finish.
Feature Classes and the Legend
Understanding features and legends is fundamental to working in GeoMedia. A feature is a geographic entity represented by geometry and by nongraphic attributes. A feature is a member of a feature class. Feature classes reside in warehouses. The Sample data contains feature classes such as States, Rivers, and Cities. Florida is a feature in the States feature class, and Rockwall is a feature in the Cities feature class.
The legend is the control center for the map window. With legend tools you add feature classes to the map window. GeoMedia gets the geometry from the feature class table and transforms it into map objects. The legend assigns default styles (display characteristics such as color, weight, and pattern) to the map objects and allows you to then customize the display properties. Each open map window has its own legend so that you can display the same feature in more than one window, in different colors or line styles.
Adding Feature Classes to a Legend
To add feature classes to a legend, perform the following steps.
3. From the list of feature classes, select States and StateNameLabels by clicking on them while holding down the Shift or Control key. Click on OK.
Changing Feature Class Styles
To change the display characteristics of the state names, you need to use Legend Properties, which allows you to change map styles, sizes, and other visual characteristics of maps. To do this, perform the following steps.
2. On the Entries tab, select the row StatesNamesLabels by clicking on the selector button to the left of the entry. Click on the Style button.
3. On the Style Definition dialog, select 8 from the Size drop-down list. Check Bold, and make sure the "Size remains constant as display scale changes" checkbox is selected. Click on OK.
4. On the Entries tab, click in the Display cell for StateNameLabels. From the drop-down list, select By Scale.
5. Click on the Scale button. In the Minimum field, type 10,000,000. Click on the OK button on the Scale Range dialog, and then click on OK on the Legend Properties dialog, shown in the following illustration.
7. Change the display characteristics of the States feature class. In the legend, double click on the Style key for the States entry. The Style key is the rectangle symbol to the left of the feature class name.
Naming Legends
Naming legends allows you to reuse them. It is possible to have many map windows open at the same time. By naming legends, you can have the same data and graphic representation in each window simply by assigning the same named legend to more than one window. When you use an existing legend, its style properties are reused, maintaining consistency in your displays.
2. In the Name field, type DisasterReliefLegend. Click on OK.
GeoWorkspace Coordinate Systems
Projections are algorithms used to transform the 3D surface of the earth to two dimensions. A coordinate system is a grid of intersecting lines;, meridians, and parallels, on a flat surface on which features from the curved surface of the earth are mapped according to their spatial location. GeoMedia recognizes two different categories of coordinate systems. The first is the projection of the warehouse, the coordinate system the data is stored in. The second is the GeoWorkspace coordinate system. This is the projection the data is displayed in.
One of the strengths of GeoMedia lies in the fact that
data from different warehouses, in different storage formats, and in different
coordinate systems, is resolved and displayed in whatever coordinate system
is defined for the GeoWorkspace. Re-projecting warehouse data to the workspace
coordinate system has no effect on the source data. In this part of the
workflow, you will change the projection parameters of the GeoWorkspace.
Defining a GeoWorkspace Coordinate System
When you display features in the map window, GeoMedia automatically converts the data from their warehouse coordinate system into the coordinate system of the GeoWorkspace. The workspace coordinate system can be defined in two ways. You can explicitly select coordinate system and projection parameters or you can instruct GeoMedia to match the workspace coordinate system with that of the first warehouse you connect to.
First you will look at the setting that allows the workspace to use the warehouse coordinate system. It is found in the Options dialog, which is used to customize many parameters in your workflows.
2. On the Storage Space tab of the GeoWorkspace Coordinate System dialog, select base storage type Projection.
3. Click on the Projection Space tab and select Albers Equal Area from the drop-down list.
4. Click on the Projection Parameters button. In the "Longitude of origin" field, enter –100:00:00:000. Enter 40:00:00:000 for the "Latitude of origin." Click on OK on both dialogs.
6. Click on View > Fit All on the Main Menu bar. You now have a more "traditional"-looking map of the United States. The re-projected map is shown in the following illustration.
You will create a new warehouse in this workflow for two reasons. First, you do not need all of the data in the Sample warehouse. You are interested in the state of Louisiana. Working with data for that states only will speed up all processing that requires database searches. Second, this workflow will require the creation of new features. In order to preserve the integrity of your sample data, the new features need to be written in a different warehouse. You will create a new warehouse and import the features you need from the USSampleData warehouse.
Creating a New Access Warehouse
To create a new Access warehouse, perform the following steps.
2. Select the template Normal.Mdt, click on Document, and click on OK New.
3. In the "File name" field, type Flood Pproject.
4. From the "Save as type" drop-down list, select Access and click on Save.
Spatial Filters
Before you import feature classes to the new warehouse, you will define and apply a spatial filter to the USSampleData warehouse. A spatial filter is an area in the map window that restricts the number of map objects displayed and the number of objects evaluated in queries. It can be a fence you place in the map window, or it can be a selected feature geometry.
The spatial filter you are going to create in this workflow will be used when you import data to the new warehouse. Putting a filter on the Sample data will restrict the import to features in and near the state of Louisiana. The import will pick up some features from surrounding states but will substantially reduce the amount of data you work with, and speed up processing.
Creating and Applying a Spatial Filter
To create and apply a connection spatial filter, perform the following steps.
Importing Data
Importing data is the process of copying data from one warehouse, the source, to another, the target. You can import data from any supported warehouse to an Access or an Oracle warehouse. Data stored in Access warehouses can be modified, added, and deleted. You need all feature classes in USSampleData for your analysis.
2 NOTE: In GeoMedia, you must import data into an Oracle read-only warehouse; in GeoMedia Pro, the Oracle warehouse can be read/write.
An important capability of GeoMedia is the ability to connect to data in many formats. It is also possible to import data from its native data warehouse into a GeoMedia Access warehouse. When you do this, you can change and add to the data. In the exercise that follows, you will import data from the larger US Access warehouse and create a smaller project-focused warehouse. Later in the book, you will learn how to do this with data from other warehouse formats. Importing Data to an Access Warehouse
To import data to an Access warehouse, perform the following steps.
1. On the Main Menu bar, click on Warehouse > Import from Warehouse.
2. Read the first panel of the Import Wizard dialog and click on Next.
3. For the source connection, select your US Data entry. Click on Next.
4. The target connection
dialog should have the new FloodProject connection preselected. This is
because it is the only open, read/write connection in this GeoWorkspace.
Click on Next. Click OK on the warning that appears. It refers to the fact
that the filter on the target, not the source, warehouse will be used during
the import.
Analysis
Since you won’t be using the US Data connection from now
on, highlight the States feature class in the map window legend and hit
the Delete key on your keyboard. From your FloodProject connection, add
Rivers and States to the legend using the Legend > Add Feature Class dialog.
. You are now ready to begin your analysis. The cartographic model you
have developed indicates that you need to build buffers around the rivers,
use the spatial analysis to find cities in the floodplain, buffer those
cities to find their neighbors, analyze the areal extent of flooding within
affected counties, develop a base map of television tower locations, generate
reports about impacted population, and produce hardcopy maps of the area.
Working in Data and Map Windows
The data window is used to display the nongraphic attribute values of your feature classes. Attributes are all the information you keep about your features. When you have a data window and a map window open for the same feature class, they are linked in such a way that items selected in one window are automatically displayed in the other. Open a data window and look at the attribute data for the Counties feature class by performing the following steps.
4. Tile the windows by clicking on Window > Tile Vertically. Select a map object by clicking on it. Notice that its attribute record is highlighted in the data window. Now click on a record in the data window. Notice that the map object displays in the map window in the highlight color defined on the Map Display tab of the Tools > Options dialog.
5. Maximize the data window by clicking on the center button on the right side of the title bar.
6. Click on the POP column heading. When the column highlights, click on Data > Sort Ascending on the Main Menu bar. Close the data window by clicking on the X on the upper right of the title bar.
7. Adjust the map window display using the View tools. The View menu on the Main Menu bar contains the commands for zooming, panning, and fitting all to the map window.
8. Suppress the display of the Counties feature class in the map window by right clicking on the Counties legend entry. From the pop-up menu, click on Display Off.
9. Remove the counties feature class from the legend by clicking on the Counties legend entry and pressing the Delete key on the keyboard. Confirm that you want to delete the feature class from the legend.
Performing an Attribute Query
The next step in this workflow is to extract only the cities and counties in Louisiana. Remember that the filter you used captured some counties in Arkansas, Texas, Alabama, and Mississippi. The data window you created in the previous step in this workflow you saw some counties from each of these states.
An attribute query looks at the nongraphic attribute values of a feature and selects features from a feature class based on an operator such as "is equal," "is not equal," "is not Null," and so on. A query outputs a query set that can be used as input to other queries. You need to build an attribute query to extract the counties for Louisiana. To do this, perform the following steps.
4. Select the equal sign from the Operators button pad.
5. Click on the Show Values button at the upper right of the dialog box. If you get the warning that processing might take some time, click on Yes. When the attribute values display, select Louisiana and click on the down arrow under the window. You have constructed an SQL query that says
8. Repeat steps 1-6, but in step 2 select the feature Cities in place of Counties. Name the query "LA cities." Notice that queries are added to the legend just as feature classes are. A display of the Cities and Counties attribute queries is shown in the following illustration.
The previous queries were based on attributes in the database. In the next section you will build queries in which the spatial location and relationships of the feature are the basis for the query.
Performing Spatial Queries
Now you need to visually ide.gify the counties that border the rivers. This query is not based on feature attributes, but on a spatial relationship among map objects. The following steps query a query. You will use the LA counties query you created earlier. Perform the following steps.
3. In the drop-down that is part of the middle field in the New Query dialog (it has the heading "That"), select touch. From the "Features in" drop-down list on the left side of the dialog box, select Rivers from the FloodProject connection. Name the query Counties on rivers and click on OK. The query set for "Counties on rivers" is shown in the following illustration.
Output a Query as a Feature Class
In order to more easily distinguish the impacted cities from the other cities in Louisiana, you will create a new feature class from the query set you just created. To do this, perform the following steps.
3. In the "Feature class" field, type impacted_cities. Feature class names cannot contain blanks.
4. Click on the "Display feature class in map window" checkbox. Optionally click on the Style button if you want to change the display properties of the new feature class. Click on OK.
Deleting Features
Now the 15 cities exist in both the Cities and the impacted_cities feature class. In this workflow you need to eliminate this duplication by deleting them from the Cities feature class. You have already created a query set named Cities on rivers and you now need to create a select set of the same features for deletion. A select set is a group of map objects selected for simultaneous manipulation. Map objects can be selected interactively in the map or data window, and they can be selected by legend entry. To delete the cities, perform the following steps.
2. Add the query to the legend with Legend > Add Query. Select Cities on rivers and click on OK.
3. Create a select set of the same cites by highlighting Cities on rivers in the legend. Click on Edit > Select by Legend Entry. The cities in the query are now members of a select set.
4. Click on the Delete button on the Placement and Editing toolbar. The toolbar is typically located on the left side of the application window. The Delete button is the red X. Answer Yes when asked to confirm the deletion. You have removed both the attributes and the geometry for the impacted cities from the "LA cities" feature class. They now reside only in the impacted_cities class.
5. Delete the "Cities on rivers" query from the legend by selecting it and pressing the Delete key on the keyboard.
6. Add the new feature class to the legend. On the Main Menu bar, click on Legend > Add Feature Class. Select impacted_cities from the FloodProject listing. The new feature class is shown in the following illustration.
Thematic Displays
A thematic map uses colors and patterns to display attribute data in the map window. The POP field in the Counties feature class contains the population for each county. You will use the POP field to create a map that displays the population of the riverfront counties in ranges. To do this, perform the following steps.
2. In the "Feature class" field on the Add Thematic Entry dialog, expand the Queries entry and select Counties on rivers.
3. From the "Available attributes" list, select POP. Click on the Range button. Click on Define.
4. On the Map by Ranges dialog, shown in the following illustration, click on the Rotate Color Scheme button until you find some colors you like. It is the left-hand button in the "Color selection" section of the dialog. Click on OK on both dialog boxes.
In the next segment of the workflow you will build 20-mile buffer zones around the impacted cities. These buffers will then be used to ide.gify surrounding cities that could potentially provide disaster relief in the event of a flood.
Creating Buffer Zones
When you create buffers in GeoMedia, you are building a new feature class. Therefore, you must be connected to a read/write warehouse. You will write your new buffer features in the FloodProject database. To build the buffer zones, perform the following steps.
3. From the "Output buffer zone to Warehouse" field, select FloodProject.
4. In the "Feature class" field, type city_buffers. This is a feature class name and cannot contain blanks.
5. You can optionally change the display of the new features with the Style key.
6. In the "Constant distance" field, enter 20 mi.
7. For the "Buffer type Point," select Single, and click on the Merged radio button.
8. Using the buffer zones, you can now create another query to ide.gify the cities located within 20 miles of the impacted cities.
9. Click on Analysis > New Query.
10. In "Features in," expand the FloodProject list and select Cities. In the "That" field, select Touch. In the "Features in" field, select city_buffers from the FloodProject connection.
11. Name the query Disaster relief cities. Click on Options and select both "Active window" and "New data window." Click on OK on both dialogs. The results of the analysis are shown in the following illustration.
Calculating Spatial Difference and Analyzing Geometry
At this point you want to look at the potentially flooded areas in a little more detail. You will add the three-mile buffer around the river and calculate the area it encompasses by county. GeoMedia provides two commands you will use to accomplish this task, Spatial Difference and Analyze Geometry. Spatial Difference allows you to subtract one area geometry from another. Analyze Geometry provides you with selected measurement statistics for feature classes or queries.
Open a new map window for this portion of the workflow using the Window > New Map Window command on the Main Menu bar. On the New Map Window dialog select the <Empty> legend and click OK. Using the Legend > Add Feature Class, add the Rivers features. Using Legend > Add Query, add Counties on Rivers to the map window.
Caption: The completed Buffer Zone dialog.
To find the portion of each county that is not in the flood zone you will first subtract the river buffer from the counties, then you will subtract those areas from the original counties.
Caption: The Spatial Difference dialog.
Caption: County areas in the flood zone shown shaded.
Caption: The completed Analyze Geometry dialog and the results in the data window.
Geocoding
Part of this workflow is concerned with the impact flooding might have on television towers around the state.
You have acquired a file of tower locations from the FCC Antenna Structure Registration Database at http://www.fcc.gov/wtb/geographic/Welcome.html#screenshots. The database contains the latitude and longitude of the towers, however it does not contain the geometry necessary for spatial analysis. Geometry can be created from coordinate data through a process called geocoding. The tower information is stored in a comma-delimited text file named LouisianaTVTowers.csv. You will make that file available in your workflow by attaching it to the FloodProject warehouse.
Caption: The completed Attach dialog.
Caption: The Units and Format dialog.
From the "Latitude" drop-down select LatDMS and from the "Longitude" list select LonDMS. Make sure that MapWindow2 is selected for the display. The dialog is shown below. Click OK to dismiss it.
Caption: The completed Geocode Coordinates dialog.
The results of geocoding are show in the illustration below. You could now perform various analyses with the tower locations.
Caption: The LouisianaTVTower locations.
You can now close MapWindow2.In the following section, you will add some labels to the display in MapWindow1.
Labels
Labels take several different forms in GeoMedia. They can be text you type in, or you can label features with attribute values stored in the warehouse. When you use attribute values as labels, they can be stored in a query or as a new feature class. Labels contained in queries are updated anytime the attribute values change. They move when you move the feature, but they cannot be edited independently of their associated features. When labels are stored as features, they are independent map objects and can be deleted, moved, or rotated.
Inserting Labels as a Feature Class
In this section you will add the city name and population for the "Disaster relief cities" query. You will store them as a feature class in the FloodProject warehouse. To add the city and population attributes, perform the following steps.
3. In the Content Attributes window, select CITY_NAME. It will move to the Layout window.
4. Click immediately behind the CITY_NAME entry in the Layout window and, while holding down the Control key, press Enter.
5. On the second line of the Layout box, type Pop; then select POP from the Attributes window.
6. Set "Alignment" to "Center center."
7. In the "Output labels as" section, select "Feature class (static, editable)." Select the FloodProject connection. In the "Feature class" field, type CityNames. Click on OK.
Map objects can be moved, deleted, digitized, and changed with the placement and editing tools. In this part of the workflow, you will clean up the overlapping labels around the New Orleans area. To do this, perform the following steps.
2. Activate the Select tool by clicking on the "Northwest arrow" button on the Selection toolbar.
3. Select one of the labels by clicking on it. This highlights the label and makes it a member of a select set. The following illustration shows a select set member.
5. Select another label and repeat step 3. Continue until you have the labels pulled apart. If you are unsure which city is which, double click on one and review the properties dialog. It includes the city name attribute.
6. You might optionally want to go to the Style dialog for the CityNames feature class and change the font and possibly other attributes. The relocated labels are shown in the following illustration.
North Arrows and Scale Bars
North arrows and scale bars are easily placed in the map window using the View tools. The following section shows you how to do this.
Placing North Arrows and Scales Bars
To place North arrows and scale bars in the map window, perform the following steps.
2. On the Main Menu bar, click on View > North Arrow. The North Arrow can be dragged and dropped at a different location. It can be modified by right clicking on it and selecting Properties from the pop-up menu.
3. You display the Scale Bar by selecting View > Scale Bar. It also can be modified by right clicking on it and selecting Properties. The final GeoMedia map window is shown in the following illustration.
ig. 4-29]
Before Going On
In preparation for the cartographic output section that follows, you need to complete a few miscellaneous steps. Performing these steps will make the resulting map easier to work with and visually more appealing.
2. Remove the spatial filter from the US Data connection. Click on Warehouse > Spatial Filters. Select <None> and click the Apply button. In the Apply Spatial Filter dialog select the US Data connection and click the ">" key. Click on OK.
3. Open a new map window by clicking on Window > New Map Window. With this window active, click on Legend > Add Feature Class. Add States from the US Data connection. Access the Legend menu again and select Add Query. Add LA Counties from the FloodProject connection.
4. Switch to MapWindow1 by clicking on Window. Click on MapWindow1.
You plot your results using the GeoMedia layout window. The layout window uses SmartFrames to store the map graphics and associated marginalia; legends, North arrows, and scale bars, originating from any of the map windows in the GeoWorkspace. The layout window contains a variety of tools that allow you to add graphic and textual enhancements to your cartographic products.
In this section, you will import an existing layout from a GeoMedia layout template. You will work with the template, add an additional SmartFrame for a U.S. locator map, and then populate all SmartFrames with the contents of your two map windows. You will see the effect of linking the map and layout windows, which allows changes in the map window to cause updates to the contents of the layout window.
The template, shown below, defines the page setup parameters and contains SmartFrames for a map, a North arrow, the legend, and the scale bar.
The Awide template.
The layout window contains working sheets and background
sheets. Working sheets define the foreground of the layout and usually
contain the graphics that are unique to a particular layout.
The background sheet contains the graphics that are used
for multiple layouts, such as logos, copyright information, and so on.
The graphics on the background sheet display behind the graphics on the
working sheet. What is shown in the previous illustration is actually the
contents of the template’s background sheet.
Caption: Placing a new map SmartFrame.
9. Place the locator map. Select the frame you created at the upper right of the template by clicking on it. On the Main Menu bar click Layout > Insert Map Graphics. Select MapWindow2 from the "Map window" drop-down. Click on Fit to Frame and select the Static radio button on the "Mode" panel. Click OK.
Caption: The Circle by Center Point button.
On the new control, shown below, select the Thick line style from the drop-down list at the far left. Click the Line Color button next to the line style field and select red from the color table. Move the cursor to the layout window and click once where you want the center of the circle located. Move the cursor the distance of the radius of the circle and click again. If you don’t like the circle, select it and click Edit > Delete. Click the Select Tool, the Northwest arrow, to exit Circle by Center. Use View > Fit to resize the layout window.
Note: If the image is not available, simply change some of the legend entry styles.
With the layout window active, select File > Print. Select the "Selected Sheet" radio button on the Print Range panel. Set the "Number of copies" to 1. If you need to edit any printer properties, select the Properties button. After making any modifications in this printer-driver specific dialog box, click OK to return to the Print Layout Window dialog box. Click OK on the Print Layout Window dialog box.
You can now create a report to go along with the map. The following section shows you how to do this.
Creating a Report
You have decided to provide the disaster relief planners with a set of charts and graphs showing the population of the cities involved. GeoMedia is designed to work with all Microsoft compliant software and you decide that the best tool to use to create the tabular data you need is Excel.
Moving Tabular Data to Excel
You want to create a report showing the populations of the impacted cities. To do this, perform the following steps.
2. Use your mouse to select all cells that include the cities’ names and populations.
3. On the Main Menu bar, select Edit > Copy or simultaneously press the Control and C keys on the keyboard.
4. Open a new Excel spreadsheet and use Edit > Paste or simultaneously press the Control and V keys on the keyboard.
5. Use the various
Excel tools to create the necessary tabular reports and charts.
