PRACTICAL EXPERIENCE WITH GPS SUPPORTED AERIAL TRIANGULATION

The operational situation of precise airborne GPS positioning of camer a air stations and its use in combined block adjustment for aerial tri angulation is reviewed The acceptance of systematic GPS errors, which occur especially with biased phase ambiguity solutions after loss of l ock of signals in-flight, has motivated the method of additional linea r GPS drift parameters which are to be solved in the combined block ad justment. It also implies that no absolute GPS co-ordinates are requir ed and that the datum transformation is provided via a few ground cont rol points. A great number of practical examples demonstrates that the method has been successfully applied within a wide range of photoscal es and of block sizes. It has proved to be fully operational under var ious practical conditions. The high accuracy performance of GPS blocks and the economic benefit have been confirmed It is particularly notic eable that the stationary receiver can be at a great distance, up to 5 00 km or more from the mission area. The conclusion is drawn that GPS supported aerial triangulation is ready to become standard. The potent ial improvement from dual frequency receivers and fast ambiguity solut ions only enhances that conclusion.