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Photogrammetry

Mapping of Tiwanaku  |  Imagery  |  Animation

The primary goal of this work was to produce some of the most up-to-date spatial data for the mapping and understanding of Tiwanaku, Bolivia. Considering the archaeological importance of Tiwanaku, and the amount of research devoted to it, one is surprised to find that most detailed and accurate published map of Tiwanaku remained the one made by Arthur Posnansky nearly a century ago (Posnansky 1945).

A total of twelve historic vertical aerial photographs (10 from 1972 and 2 from 1992) were purchased from the Bolivian government as hard copy negatives, and scanned to produce roughly 13 gigabytes of digital data. Because the photos contained full stereo coverage, we were able to produce two photogrammetric block files; 1972 and 1992. Initially, very little was known about these photos and a form of "forensic photogrammetry" had to be done in order to use them. 

A number of the archeological monuments (more specifically, individual stones) could clearly be seen in the photographs, and the corners of most stones had been surveyed by archeologist working in Tiwanaku with total station equipment. This made it possible to extract coordinates for a number of features and use them as ground control points (GCP) for the photogrammetric work.

Elevation data was extracted from each stereo pair and mosaiced to produce a Digital Terrain Model (DTM) of all overlapping areas. The elevation model produced from the stereo pairs, along with results from an aerial triangulation, was then used to orthorectify the raw imagery. With the removal of most geometric distortions, the result was a planimetrically true orthoimage from which valuable geographic information can be collected using both metric and interpretive methods. Visual examples of these spatial data can be seen at the above Imagery and Animation links.

A secondary goal of this project was to investigate potentials for fusing photogrammetrically derived spatial data with other, multi-scale spatial data including: High Density Survey (HDS), sub surface geophysical, and total station survey data. For information and results of this work, visit our Data Fusion page.

Spatial data from this work are available for dissemination via download from the Internet Virtual Metrology Lab (InVirMet) website of the Center for Advanced Spatial Technology at the University of Arkansas and the Proyecto Arqueologico Pumapunku-Akapana.