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Title
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Assessment and correction of DEM generation from airborne and space borne radar systems with reference to geo-hazard identification in the Cameron Highlands, Malaysia.
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| Author(s) |
Ahmad, Baharin Bin, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW
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| Resource Type |
Thesis
PhD Doctorate
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| Supervisor(s) |
Milne, Anthony K., Biological, Earth & Environmental Sciences, Faculty of Science, UNSW
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| Keyword(s) |
InSAR
AIRSAR
SRTM
DEM
Aerial Photograph
Digital mapping
Surveying -- Data processing
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| Date |
2008 |
| Description/Abstract |
This research assesses the accuracy of SRTM and AIRSAR DEMs acquired over the mountainous-hillands of Cameron Highlands
with DEMs generated from Digital Aerial Photograph (DAP) with a fine (2 m) spatial resolution and height resolution of about 0.5 m. The
ground control points used for generating stereo models from the DAP were acquired during field work using GPS which achieved
accuracy better than 2 cm in most cases.
To overcome the difficulty of overlaying the DEMs with the DAP DEM as no features can be easily identified on both the images,
therefore a technique of using transects and contours generated from the DEMs were used to correct the horizontal displacement. For
AIRSAR DEM, comparing the accompanying AIRSAR composite images was also employed. These then allowed an analysis of the
height accuracy to be undertaken.
The height of both the AIRSAR and SRTM DEMs were also corrected by applying Linear Regression Models. These models were
produced by comparing pixels obtained from points, profiles and an area. Once again the corrected DEMs were assessed. Finally the
extracted profiles and contours from the corrected SRTM and AIRSAR were compared with the reference DEM.
From the comparisons, the horizontal errors were found to be about one and the half pixels (138.72 m: for SRTM) to the east and 1
pixel (10 m: for AIRSAR) to the south. The SD of height differences of the SRTM and AIRSAR DEMs using 90% data were 9.2 m and 5.2 m
with profiles comparison; 10.4 m and 5.4 m with area comparison; 10.8 m and 2.4 m with GPS GCPs comparison respectively. From the
three comparisons, the means of height differences are 5.2 m, 6.1 m and 15.2 m for SRTM and 8.1 m, 8.3 m and 7.9 m for AIRSAR DEM.
The results suggest there is height offset in the AIRSAR DEM. When both heights of DEMs were corrected, the generated contours are
close to each other and to reference contours. Using contour colours images and height modelling, the corrected DEM was found to
have the potential to detect areas that prone to flash floods and mudslides. |
| Language |
EN |
| Rights |
Please click here to view the rights |
| Print Availability |
T/2008/71 (Ask at Level 2 Information Desk, UNSW Library) |
| Citation Link |
Please use this identifier to cite or link to this item: http://handle.unsw.edu.au/1959.4/41422 |
| Full Text | 
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| Total Attachment(s) | 3 |
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