Figure 4: Flight-lines of the first test-flight after differential GPS processing. The images 
are marked by circles. 
Image coordinates can be measured in any digital image 
processing system on a computer monitor. We used the 
ERDAS Digital Ortho Module for image analysis. A number 
of check and tie-points were measured in the digital images. 
Together with the GPS flight-lines, the interior orientation 
and the offset vector a bundle triangulation can be computed 
to determine the exterior orientations of all photos. The 
orientation data is applied for various post-processing tasks, 
e.g. the derivation of digital elevation models (DEMs) and 
orthophotos. Figure 5 shows a MapCam image of the 
Columbus Zoo. 
  
Figure 5: MapCam image covering the Columbus Zoo. The 
ground resolution is 25 cm per pixel, the image covers an 
area of 320 m by 256 m, and was taken at a flying height of 
300 m above the ground. 
5. CONCLUSIONS 
Although research on MapCam is not completed yet, we 
found that a digital, aerial, GPS-controlled mapping system 
has a great potential for fast, spatial data collection. The 
major advantage over conventional aerial surveys is its quick 
turn-around time, as digital imagery is immediately available 
for image analysis after the flight. The resolution of digital 
cameras will not match film in the near future, but for many 
applications, MapCam provides enough detail and accuracy. 
Digital mapping cameras will become especially important 
with the availability of digital softcopy workstations. As 
scanning of aerial photography is a very time consuming and 
expensive task, users will sacrifice resolution for speed and 
currency of the data. 
The current version of MapCam is still closely related to 
conventional, aerial mapping systems. However, there are a 
number of enhancements and modifications we plan in the 
future. First, a number of video cameras of lower resolution 
should be added. Each one would be equipped with a filter 
to capture à narrow spectral band. This would result in 
multispectral, aerial images, which could be applied for 
various remote sensing tasks. The other major enhancement 
would be the installation of a camera-pair in an airplane to 
map 3-dimensional positions in real-time. A major 
application would be the mapping of power-lines. The two 
cameras would be installed at the wing-tips. This would 
allow for stereo-positioning in a local coordinate system 
relative to the airplane. If the plane would fly relatively low 
the accuracy would be acceptable for many applications. In 
order to get absolute coordinates three GPS antennas would 
be installed at the wing-tips and the vertical stabilizer. They 
would provide both global positions and attitudes of the 
aircraft. This so-called Utility Mapping System is currently 
being designed at the Ohio State University; we believe that 
it will allow the user to map global positions form an 
airplane in real-time.