ELEVENTH INTERNATIONAL CONGRESS OF PHOTOGRAMMETRY 
LAUSANNE, SWITZERLAND, JULY 1968 
Commission IV - Presented Paper 
PLANIMETRIC ACCURACIES IN SINGLE MODEL TRIANGULATION 
G.E.BELLING, South Africa 
Abstract 
Control for medium and large scale mapping is often obtained from a combination 
of ground survey and aerial triangulation techniques. Where height and planimetric 
accuracy specifications differ, it is not unusual to fix the planimetric control 
by aerial triangulation and the height control by direct spirit levelling. In 
such cases, a combination of high flown/low flown photography provides the basis 
for obtaining the planimetric control for the mapping project. 
In this paper, results obtained from a number of experiments carried out on a test 
overlap are presented. Effects on the accuracy of the derived planimetric 
coordinates due to model scale variations are investigated together with an analysis 
of results with different control densities and distributions.