International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
Department of Transportation (ODOT). The Range is centered
at latitude 39? 56' 25" N. and longitude 83? 31' 28" W. Figure
I. displays the Madison Range.
The targets are painted on existing asphalt roads and are
centered on magnetic PK nails. Targets are 2.4 meters in
diameter with a 0.80 meter flat white center. The targets were
designed to provide optimum images for automatic pointing
and recording of image coordinates for film-based cameras
flying at about 1200 meters above the field. Figure 2. shows
the ODOT personnel as they prepare a standard target on the
Madison Range.
In order to image sufficient targets on a single photo, when
using conventional digital cameras, targets were densely
distributed in the vicinity of the intersections of US40, Potee
Road, and Markley Road. In the vicinity of the intersection,
targets were separated by 10 meters. As targets radiated from
this intersection, the intervals were sequentially increased by
the cube root of 2. In this way, relatively narrow field cameras,
flying at low altitudes, can acquire sufficient target images for
calibration purposes. The target distribution for use by low-
flying or narrow field camera systems is shown in Figure 3.
Figure 1. The Madison Test and Calibration Range
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Figure 2. ODOT Personnel Preparing a Target
3.2.2 Resection Comparisons to GPS Exposure Station In
order to demonstrate the improvements offered by an in situ
approach to camera calibration when compared to a
conventional laboratory calibration, two single photo resection
computations were computed using first the results from a
laboratory calibration and then computed from results of an in
situ calibration. The exposure station coordinates for each case
were compared to the station coordinates derived from GPS.
The concept is indicated in Figure 4.
Figure 3. High Density Range for Digital Cameras
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