| Abstract: | In conventional aerial photogrammetry, the high accurate photogrammetric point determination is always carried out by aerotriangulation
using a great deal of ground control points around the perimeter and in the center of block area because the exterior orientation
parameters of aerial photographs are unknown. A technological revolution in photogrammetry has taken place since Navstar global
positioning system (GPS) was applied to determine the 3D coordinates of exposure station positions during the photo flight
missions. GPS-supported aerotriangulation is conducted by a combined bundle adjustment for photogrammetric observations and
the camera orientation data. In this case, the essential ground control points are replaced by GPS-determined camera positions.
Recent investigations show this method is coming to the practice. We have been engaged in the theoretical studies, soft-ware
development, and related experiments and production in the field since 1990. So far the abundant research achievements are
obtained in terms of the theory and application. In this paper, we first derives the mathematical model of GPS-supported aerotriangulation
from the geometry between camera and airborne GPS antenna, then describes briefly a software package WuCAPS (Wuhan combined
adjustment program system) developed newly by the author, which serves the purpose of the combined bundle adjustment for photogrammetric
and non-photogrammetric observations. At the end of the present work, a set of actual aerial photographs, at the image scale
of 1∶34 000, with airborne GPS data taken from Tianjing site, China were processed by WuCAPS. The empirical results have verified
that the accuracy of the combined bundle adjustment with 4XYZ ground control points around the corners of block area is very close to that of the conventional bundle adjustment with 3
additional parameters, that leads to reduce 88% field survey and 75% production cost, and can meet the specification of topographic
mapping at small or medium scale by GPS-supported aerotriangulation without ground control. This shows the ample applicability
and the economic benefit of kinematic GPS relative positioning in high accurate photogrammetric point determination. |
