MAP UPDATION AND TERRAIN MODELLING 
Krishna Kumar Naithani & Pran Nath Koul 
SURVEY OF INDIA 
Commission-IV, Working Group IV/3 
KEY WORDS : Map, Updation, Terrain, Modelling, Sterteo, Imageries 
ABSTRACT : 
The advent of satellite stereo-imageries have revolutionised the photogrammetric techniques. The 
development in hardware and software techonology has enabled the production of sophisticated digital 
photogrammetric systems which facilitate setting up of spot stereo-imagery. 
Stereo-imageries, unlike photographs, are acquired by satellite born sensors in a dynamic and time 
dependent mode. The advanced version of digital photogrammetic workstations support setting up of 
the SPOT-stereo models and make it possible to establish the co-relation between the 3-dimentional 
model, created by the stereo-imagery, and the ground truth within fair accuracy limits. The existing 
digital files, of the area of interest and the additional data, the cultural details natural features and 
topography can be extracted by stereo-digitization through analytical operations. The data thus gener- 
ated can be merged with the existng data to get an updated version of cartographic product. This makes 
the satellite stereo data an important source of GIS information. The authors have carried out elaborate 
studies by selecting a few test areas and attempted solution of a few SPOT stereo models for updating 
the existing cartographic products. The outputs have been varified broadly with respect to the ground 
truth and analysed statistically. The statistical analysis has revealed encouraging results. This paper 
briefly describes the equipment used, the technique adopted and the conclusion drawn after the analysis. 
1. INTRODUCTION India, Dehradun to workout the feasibility of 
updating 1:50,000 scale maps by using setreo- 
The advent of computers has revolutionised the ~~ imageries in combination with aerial photogra- 
map making techniques and enabled transition phy. 
from conventional mapping to digital mapping. 
This transition was highly warranted to meet the 2. AIM 
demands of map users, which have been changing 
at an appreciable pace, mainly because of the The aim of the project was : 
application of maps in planning, execution and a) To idetify the limit upto which stereo-image- 
monitoring of developmental projects / activities. ries could be used for change detection and sub- 
The users’ requirements have been becoming sequent updation of the existing maps on 
more and more demanding due to the availability 1: 50,000 scale. 
of digital cartographic data bases. The carto- 
graphic data bases need to be updated by a proc-  b) To find out if reference to aerial photography 
ess which should be speedy and at the same time (and not setting up on photogrammetric worksta- 
cost-effective. It is here that sereo imageries may tion‘) will facilitate further interpretation of addi- 
offer a promissing solution for updation of the — tional features / details. 
existing maps / cartographic data bases, if used 
carefully. With this aim in mind a project was — c) To collect DEM data and generate contours at 
taken up in Digital Mapping Centre, Survey Of a suitable contour interval for evaluation of DEM 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
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