The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
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Table 3 shows the effect of DEM resolution in generating ortho 
image. The differences in latitude and longitude between ortho 
images generated from 5m DEM and 2.5m DEM is negligible. 
The differences are of the order of a meter in Longitude and 
0.5m Latitude in respectively between ortho images derived 
from 10m DEM and 2.5m DEM. 
Figures 5a and 5b reveals that the maximum slope are falling in 
the category of 15°-25° and 25° - 40°. The aspect analysis, as 
shown in Figures 6a and 6b, reveals that the maximum aspect 
are falling in the South and north direction. 
Analysis of drainage network shows that there are not many 
differences in the number of higher order drainage. Only lower 
order drainages are getting affected by the DEM resolution size. 
As shown in table 4, there is a difference of 8, 4 and 1 in the 
number first order, second order and third order drainages 
respectively. 
9. CONCLUSIONS 
The model accuracies at GCPs and check points were derived, 
by changing the number and distribution of GCPs. The 
planimetric and vertical accuracies were respectively 4.3m, 3.5 
and 3.1m in longitude, latitude and height by taking 10 GCPs 
and Polynomial order 2. There is an improvement in model 
accuracies also. The effect of DEM resolution on Ortho image 
accuracies show that enough care has to be taken in selecting 
DEM resolution while generating an ortho image. Mainly it 
depends on the type of applications in our hand. Terrain 
parameters such as slope, aspect, and drainage network were 
automatically extracted from DEM. Drainage network analysis 
shows the DEM resolution size affects the lower order 
drainages while varying the DEM resolution from 5m to 10m. 
REFERENCES 
Crespi M., F. Barbato, L.D. Vendictis, R.Onori, D. Polic, 
F.Volpe and X. Wang, 2006. Orientation, ortho-rectification, 
DSM extraction and 3D city modeling by Cartosat-1 stereo 
imagery: First results of a test over Rome. In: The International 
Archives of the Photogrammetry, Remote Sensing and Spatial 
Information Sciences, Goa, India. Vol. XXXVI, Part-IVB, pp. 
1020-1025. 
Chen, L. C., T. A. Teo, and C. L. Liu, 2006. The geometrical 
comparison of RSM and RFM for FORMOSAT-2 satellite 
images. Photogrammetric Engineering & Remote Sensing, Vol. 
72(5), pp. 573-579. 
Dabrowski R., M. Kedzierski, W. Fedorowicz, R. Kaczynski 
and J. Zych, 2006. Geo-interpretation capabilities and precision 
of an ortho-photomap obtained from Cartosat images. In: The 
International Archives of the Photogrammetry, Remote Sensing 
and Spatial Information Sciences, Goa, India. Vol. XXXVI, 
Part-IVB, pp. 1038-1040. 
Di, K., R. Ma, and R., Li, 2003. Rational Functions and 
Potential for Rigorous Sensor Model Recovery. 
Photogrammetric Engineering & Remote Sensing, Vol. 69(1), 
pp. 33-41. 
Fracer, C. S., and H. B. Hanley, 2005. Bias compensated RPCs 
for sensor orientation of High Resolution Satellite Imagery. 
Photogrammetric Engineering & Remote Sensing, Vol. 71(8), 
pp. 909-915. 
Jeson, S. K., and J. O. Domingue, 1988. Extracting topographic 
structure from digital elevation data for geographic information 
system. Photogrammetric Engineering & Remote Sensing, Vol. 
54(11), pp. 1593-1600. 
Li. R, F. Zhou, X. Niu, and K. Di, 2007. Integrating of 
IKONOS and QuickBird imagery for geo-positioning accuracy 
analysis. Photogrammetric Engineering & Remote Sensing, Vol. 
73(9), pp. 1067-1074. 
Michalis P. and I. Dowman, 2006. Sensor model evaluation and 
DEM generation for Cartosat-1. In: The International Archives 
of the Photogrammetry, Remote Sensing and Spatial 
Information Sciences, Goa, India. Vol. XXXVI, Part-IVB, pp. 
1009-1013. 
Nadeem, A, M. Anjum, A. Ritesh, P. Jayaprasad, S. K. Pathan, 
Ajai, D. K. Singh and A. K. Singh, 2007. Extraction and 
Validation of Cartosat-1 DEM. Journal of the Indian Society of 
Remote Sensing, Vol. 35(2), pp. 121-127. 
Poon, J., C. S. Fracer, and C. Zhang, 2007. Digital Surface 
Models from High Resolution Satellite Imagery. 
Photogrammetric Engineering & Remote Sensing, Vol. 73 (11), 
pp. 1225-1232. 
Rao B.S., A.S.R.K.V. Murali Mohan, K. Kalyanaraman and K. 
Radhakrishnan, 2006. Evaluation of Cartosat-1 Stereo Data of 
Rome. In: The International Archives of the Photogrammetry, 
Remote Sensing and Spatial Information Sciences, Goa, India. 
Vol. XXXVI, Part-IVB, pp. 1026-1029. 
Ritesh A., A. Nadeem, P. Jayaprasad, M. Anjum, J. A. Vinoth 
Kumar, S.K. Pathan and Ajai, 2006. Comparative evaluation of 
various algorithms for drainage extraction using Cartosat-1 
stereo data. In: Asia Pacific Remote Sensing Symposium Goa, 
India. SPIE, Vol. 6411, 6411 Ox. 
Tao, C. V., and Y. Hu, 2001. A Comprehensive Study of the 
Rational Function Model for Photogrammetric Processing. 
Photogrammetric Engineering & Remote Sensing, Vol. 67 (12), 
pp. 1347-1357. 
Tao, C. V., Y. Hu, and W. Jiang 2004. Photogrammetric 
exploitation of IKONOS Imagery for mapping applications. 
International Journal of Remote Sensing, Vol. 25 (14), pp. 
2833-2853. 
ACKNOWLEDGEMENTS 
Authors express their sincere gratitude to Dr. R. R. Navalgund, 
Director, Space Applications Centre, Ahmedabad for his keen 
interest and guidance. Authors are thankful to Dr. J. S. Parihar, 
Deputy Director RESA, Dr. Manab Chakraborty, Group 
Director GTDG and Dr. Ajai, Group Director MESG, Space 
Applications Centre for their valuable suggestions during the 
study. Authors are extremely happy to acknowledge the help of 
Mrs. Anjum Mahtab, Scientist National Remote Sensing 
Agency, Hyderabad and Mr. Nadeem Ahmad, Nirma University, 
Ahmedabad during the execution of work.