14 
out in such a way that each conventionally rectified complete photograph 
(of flat terrain), or each pair of half photographs (of non-flat terrain) rectified 
differentially from the same diapositive in two successive stereo models, 
covered one map sheet only. In such a case a minimum number of orthophoto 
negatives would be required to form one map sheet, while in each sheet the 
radial displacements of objects rising above the terrain would radiate from 
the same radial centre. Also evenness of grey tones is then easily obtainable, 
in the case of differential rectification,by always developing the two half 
photographs together. 
From the assembly of orthophoto negatives, photomap sheets can be 
produced (in the form of dyeline copies, bromide copies, or off-set printed 
copies), annotated with grid, names, contours and spot heights, and—if 
required—with soil type or vegetation strata lines, etc., by following proce- 
dures such as those described in the ITClecture notes on Cartography by 
van Zuylen and Shearer, or by Urban (Central Mapping Authority, Australia) 
in a paper Large Scale Mapping in New South Wales, presented to the 7th UN 
Regional Cartographic Conference for Asia and the Far East, Tokyo, October 
1973. 
When the definition of the cadastral boundaries in the terrain (see 
1.5.1 above) has been done by annotation on enlargements of the original 
photography, the photo maps can easily be annotated with these boundaries 
in the following way. A contact copy of the ortho negative assembly is made 
onto a scribing sheet coated with a photographic emulsion (e.g. Stabilene 
Contone, by Keuffel and Esser). When the scale of the enlargements is about 
equal to that of the photomap, a simple mirror stereoscope such as the ITC 
Stereoscan can be used for the transfer of the cadastral boundaries to the 
photomap; otherwise a mirror steresocope with differential optical enlarge- 
ment is needed. The cadastral boundaries can next be scribed into the coated 
scribing sheet. By successive photography of the ortho negative assembly and 
the scribed sheet, using the proper means of registration, the cadastral boun- 
daries will appear on the resulting positive orthophoto in black. From this 
scribed sheet conventional line maps of the cadastral situation can also be 
produced by off-set printing, if desired. It should be noted here that the line 
plotting is done from the orthophoto and is thus not dependent on an ex- 
pensive photogrammetric plotter.