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Poster Session 1
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Using High Resolution Satellite Imageries to updata Topographic map and for Monitor Land use Changes
3.7 Land use changes such as new roads, boundary of residents, rice fields, plantation, forest etc. were digitized. The row and column number were transferred to be UTM coordinates.
3.8 Output of digitized features is a hard copy by using a pen plotter.
4. Result and Discussion
Four control points, 12 km apart, at the corners of the image are sufficient to transfer digitized features to obtain planemetric accuracy within 7 (seven) meters.
AFFINE mathematics seems to be the best in coordinates transformation in comparison with ORTHOGONAL and POLYNOMIAL.
However, a control point which is mis-identified or wrong surveyed nay jeopardize the map updated in views of geometric accuracy.
AFFINE is the least effective method in detecting blunder of a control point while ORTHOGONAL is the best.
Therefore, using only 4 ground controls, within some 10km apart, at the corners of the area, the validity of coordinates and digitized data should be checked prior to coordinates transformation be made.
The report demonstrates only roads (new or re-allocated), main canals and boundaries of main features were updated. Minute details such as new building, cart track, fences etc. were not updated due to difficulties in interpretation of these features.
It must be noted that, some minute details such as a house that is contrast to the surroundings or even a rail road are interpretably by SPOT PLA displayed on VGA monochrome (a historgram equalization).
The methodology mentioned in this report works well with flat and medium hilly terrain, and by using near vertical angle imagery.
For mountainous area and off nadir viewing angle, relief displacement and image rectification must be calculated for coordinates transformation.
Fig. 1 Study area
Fig. 2 Location of 52 checking points and ground control
5. Conclusion
The outstanding advantages of the application of SPOT PLA by using this methodology is time and cost savings. The plaemetric accuracy of the digitized features can be achieved within 7 meters which is sufficient to update map (the interpretable features) at scale up to 1:20,000. Further, the digital nature of satellite data facilities data handling and data conversion into other formats and produce map at any scale.
Acknowledgement
The work was conducted as a part of topographic map updating in Pasak Basin. It was financial supported by National Research Council. Recognition is extended to Kasetsart University and Royal Irrigation Department for their administrative and technical cooperation.
References
- G.KONECNY et. Al. Evaluation of SPOT Imagery on Analytical Photogrammetric Instruments, Photogrammetric Engineering and Remote Sensing, Vol. 53 No. 9, Sept. 1987, pp 1223-1230.
- Paul H. Salamonowicz, Satellite Orientation and Position for Geometric Correction of Scanner Imagery, Photogrametric Engineering and Remote Sensing, Vol. 52 No. 4, April 1986, p 491-499.
- S.D. DeGloria and A.S. Benson, Interpretability of Advanced SPOT Film for Forest and Agriculture Survey, Photogrammetric Engineering and Remote Sensing, Vol. 53 No. 1, January 1987, pp 37-44.
- J.R. Eyton, SPOT PLA Photographic Image Processing, Photogrammetric Engineering and Remote Sensing, Vol. 56 No. 8, August 1990, pp 1129-1134.
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