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planning and design of a new office complex. In the 
United Kingdom there are several aerial photographic 
libraries and archives held by various organisations. EPU 
make full use of these services for two main reasons, 
firstly it is considerably cheaper than commissioning new 
photography and secondly the material 1s readily available 
and this reduces project take up time. Suitable vertical 
aerial photography at a scale of 1:5000 was located for this 
particular site. 
In conventional mapping photogrammetrists normally 
digitise detail that is traditionally shown on maps and 
plans by its outline or silhouette. For this project it was 
necessary to adapt the approach so that the detail digitised 
not only represented ground features accurately but gave 
a good visual impression of how these features actually 
appear (Fig. 1). Roof detail was digitised indicating their 
pitch, major details on the roofs themselves, tree canopies 
indicating height and spread, fences and walls showing 
width and height. The ground surface was represented by 
0.25 metre contours (Fig. 2) which were derived from 
pertinent ground detail (kerb lines, boundaries etc.), a grid 
of spot heights and supplementary height points on 
important natural changes of slope processed using a 
digital terrain model package. 
  
Fig. 2 3-d detail with DTM derived contours 
The coordinate system for the model was the project 
coordinate system and would be used to generate all 
setting-out data for the construction of the new complex. 
Therefore permanent coordinated groundmarks were 
distributed around the site and their positions included in 
the CAD model. A field completion exercise was 
undertaken in order to include obscured and missing 
features. This included building groundlines if there were 
large overhangs or if they had sloping walls, tree boles and 
the identification and coding of hundreds of utility 
inspection covers. This exercise involved the use of 
electronic tacheometers and also simple "tape and offset’ 
measurements for some features. This additional detail 
had to be added to the original dataset using Microstation 
on an Interpro 125 workstation. This editing was not as 
straightforward as was initially thought. The 
3-dimensional nature of this project meant that it was no 
longer acceptable to simply extend lines to intersect in 
plan but variations in elevation also had to be considered. 
Also included in the field completion exercise was the 
checking by ground survey of the position of certain 
critical structures on the site. It then proved necessary to 
move the photogrammetrically derived models of these 
buildings, by less than 50mm, to produce a consistent 
model. 
Inner-city redevelopment areas 
Architects have for some time been aware of the 
advantages of 3-dimensional computer graphics, for the 
planning of new projects through to the production of near 
photographic quality visualisations. Until recently 
photogrammetry has been used for the production of 
conventional site plans and more detailed facade details. 
These are normally supplied in a 2- dimensional form on 
paper or film and, more recently, in digital form on a 
floppy disk, However whatever format is delivered the 
amount of additional information that can be obtained 
from this "flat" product is limited. Architects have had to 
create 3-dimensional models from this 2-dimensional data 
source. This has involved them approximating building 
heights by counting brick courses and estimating window 
sizes and has led to unsatisfactory and inaccurate results. 
  
Fig. 3 Oblique photograph taken with UMK 10/13181 
  
  
  
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Fig. 4 3-d Line string representation of facade detail 
EPU were asked to produce a 3-dimensional model of a 
redevelopment area of London. The specification required 
a simplified block model of all structures with selected 
facade information, road edges and some detailed facades