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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
Komate Hongpakdee1, Pipat Sonwong 1, Suwana Euwaanon 2, Krisna Klindad 2 and orawn Sudchukiat 2
1Kasetsart University, Bangkok, Thailand Tel 579475
2Royal Irrigation Department, Nonthaburi, Thailand Tel 5838436
Abstract
Knowledge of national resources, land use and land cover information are essential for successful regional planning and land development. Satellite imageries have been proved as an efficient information for land use mapping, imageries have been proved as an efficient information for land use mapping. It is increasingly being used for cost effective information extraction pertaining to earth surface. This paper report a practical application SPOT PLA for Topographic mapping revision and monitoring the land use changes. The planemetic accuracy was investigated.
Three mathematics algorithms AFFINE ORTHOGONAL POLYNOMAIL coordinates transformation were applied to compare accuracy achieved and the effectiveness of each in detecting blunder of ground controls.
The report demonstrates a practical application of SPOT PLA to up-date a topographic map at scale 1:20,000 regarding geometric accuracy.
Introduction
Pasak Basin covers 14,000 sq. km. Situated at central part of Thailand. The government planned to build a dam at the study area for irrigation purpose and flood release in Chaopya Basin especially the Bangkok Metropolis and the sub-urbans. The reservoir storae is approximated 9,000 m.cu.m.
A feasibility study had been tried by using available topographic map at scale 1:10,000 with 1 meter contour interval prepared in 1973 by photogrammetry. Due to large changes of land use in 1973 compared to 1989, an up-to-data topographic map is needed.
- Aims of Works, Problems and Solution
- Collecting up-to-data land cover information only in planemetric details.
- The ground survey or photogrammetry is time consuming and expensive.
- With the advent of high resolution satellites, a new dimension was added to the field of land cover information collection of this project, e.g. updating the 16 year-old map at the dam site area by using SPOT PLA.
- Data Used and Working Area
The work was emphasized on the planemetric accuracy of images of SPOT PLA to updata map details. The scene center is at latitude 14.9 degree N and 101.5 degree E acquired on 1989-02-09.
The image has following characteristics
- Near vertical (<3 degrees camera till angle)
- Covers most part of the reservoir and damsite
- 0 % cloud cover
- Highest resolution satellite imagery monitoring in Thailand
The area is convenient for ground survey (traversing) and field check (the ground truthing). It is 1/3 flat 1/3 hilly and 1/3 mountainous.
3. Methodology
3.1 52 points which are discernible and identifiable on both ground and on the image were selected as control points for coordinates transformation and for independent checking point to verify the planemetric accuracy of the SPOT PLA.
3.2 The selected points are undoubtful in identification and identity.
3.3 The control and the independent checking points were surveyed by third order traversing, originate from and closed to existing monuments which were surveyed by second order accuracy.
3.4 Since the working area covers 12.8 x 12.3 sq km which is equivalent to 1280 x 1230 dots or pixels, the area then was devided into 9 sub-images. Each sub-image contains 640 x 80 pixels to fit a monochrome VGA monitor that can display one sub-image at a time.
The sub_image has overlaps to the adjacent sub-image.
3.5 The 9 sub-image displayed on monitor were digitized obtaining row and column number of those 52 surveyed points.
3.6 The pre-selected control points of 4-6-8-9 points digitized were verified according to mathematics algoritas as mentioned.
The unknown parameters were calculated to transform digitized data to be UTM nothing and easing coordinates.
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