Ground Truth Survey for the Development of Current
Land use map, the western seaboard Regional
development Master plan study, Thailand
Sripen Durongdej1, Pornthip Kanchansunthorn1, K.Honda2, Shanker Pathak2,
Nguyen Van Dai2, Satya Priya2, Lal Samarakoon3, and Seetharam K.E.3
1Deperatment of Geography, Kasetsart University
Phahon Yothin Road, Chatuchak, Bangkok 10900, Thailand
Tel:66-2-561-3480 ext 710 Fax: 66-2-472-6304
E-mail: [email protected]
2GIS Application Center (GAC),
Asian Institute Thani 12120,Tah
P.O. Box 4, Khlong Luagn, pathum Thani 12120, Thailand
Tel: 66-2-524-6149 Fax: 66-2-524-6147
E-mail: [email protected]
3Nippon Koei (Japan)
2304 Takasaki Kukisaki Inashiki Ibaraji Japan
Tel : 81-298-71-2040, Fax: 81-298-71-2022
E-mail : [email protected]
The western Seaboard Regional Development Master Plan Study is a joint project between the Japanese government and the Thai government. The project aims to develop a master plan study for the western seasboard region in Thailand and to develop a current land use maps using remotely sensed data. The Geographic Information System (GIS) database is also developed for mapping facility and for facilitating future development plan of the region.
To identify land use classes and land cover, a systematic ground truth survey is established by three involved agencies. An interpretation key sheet is developed to be used during the ground turthing process in order to provide key features for further visula image interpretation. During the ground truth survey, GPSs, topographic maps of the selected area, printed Landsat-TM sheets, and cameras are essential needed equipment. An interpretation key sheet consits of descriptions, of land cover; UTM coordinates and/or latitude and longitude values taken by the GPSs; details of the topo map sheet; a photograph of the selected location and comments. Interpretation on the Landsat image is roughly prepared in the field. Visul image interpretation is applied for the development of current land use maps based on ground truth key sheets and th topo maps. Key sheets can be used effectively for visual interpretation.
It is recommended that satellite images should have been geo-corrected before conducting the ground truth survey. It is recommended that a powerful notebook computer with a CD-Rom drive should be utilized during the field survey to facilities the ground truthing.
the Western Seaboard Regional Development Master Plan Study is a joint project between the Japan International Cooperation Agency (JICA) which represents he Japanese government, and the National Economic and Social Development Board (NESDB) which represents the Thai government. This project aims to develop a plan study for the western seaboard region in Thailand. It also aims to develop a Geographic Information System (GIS) database for the development plan of the region. Physical data collected from various involved government agencies are required for such purpose.
The initial stage of the study is to identify land cover and land use classes of the whole region and to map them. Remote sensing data are used for updating current land use and land cover. For Classification of remoe sensing data, ground truth data are the essential information in elating the remotely sensed data to the real land cover characteristics. In so doing, the Department of Geography (GOC), kasetsart University, the GIS Application Center (GAC), and the Nippon Koei (Japan) have together established a systermatic ground truthing method, using Landsat0TM data, for the development of current land use map of the western seaboard region. In this project, DOG is assigned to conduct the ground truth survey of the region and to prepare key sheets which provide significant ground truth data for satellite image interpretation, Based on the provision of the ground truth data, GAC further interprets and analyses images of the whole area, and prepare current land use maps using GIS facilities. This paper presents the systematic methodology applied in conducting the ground truth survey, preparation of key sheet to be used later as guidance for satellite image interpretation, and brief description of how map is developed from the field survey results.
2. Purpose of the Ground Truth Survey
The main purpose of ground truthing is to collect basic information from realities for satellite image interpretation and landuse mapping. Our purposes can be described as follows.
To identify land use or land cover of the real location and then compare it to what is shown on the image.
- On the image, identify colours, tone shape, texture, location and size. Such information provides basic guidance for further image interpretation of similar land use category in other areas. The basic guidance is in the from of key sheets.
- To verify and update existing data especially data on the map sheets or topographic maps. Also to verify the pre-interpreted image data that have been done prior to ground truthing.
- To collect more related data from local people. Interviewing or asking local people for more details such as location, land use activities, settlement history, and timing will help understand land use and cover better. It also verify image interpretation of inaccessible areas.
In conducting a field survey, researchers must have a basic understanding of the study area such as it physical characteristics , location framing pattern, local agricultural products, main occupations, and its socio-economic status. This basic knowledge provides fundamental ideas for identifying entities appeared on the imageries and thus, ease the interpretation process during the ground truth survey.
3. Ground Truth Survey for the Western Seaboard Region.
According to the delineation of the western seaboard region , the ground truth survey covers some districts of Kanchanaburi province, and other five nearby provinces namely Samut Songkhram, Ratchaburi, Phetchaburi, Prachuap Khiri Khan and Chumporn. The survey was intensively conducted during 6 April to 16 May, 1996, with total number of 568 survey points. Numbers of survey points in each province vary to its size. Larger size provinces have bigger numbers survey points. The total
568 survey points of the six provinces provide enough raw data for visual interpretation. The distances of the survey points, as in many cases, range from 2 to 4 km.
Total area of the western seaborard region is 2,762,831 hectares or 27,628 km2 containing 41 districts in six provinces. The shape of the western seaboard is long and narrow with the approximate length of 600 km. In distance.
Equipment utilized in the field
Two GPSs (Global Positioning System) : one Sony, and one Magellan. These are used for defining UTM coordinates and latitude and longitude values of each survey point.
- Two sets of 1:50,000 topographic map sheets-one original and one photocopied. Each topo map provides real UTM coordinates and latitude and longitude values, location of each survey point, and land cover information.
- Landsat-TM images at the scale of 1:100,000 taken during March-May, 1995. The Landsat-TM raw data have been enhanced by standard false color combination of R:G:B using combination of band 4:3:2 respectively. Data of the entire area were printed on totally 120 A4.
- Cameras for taking colour picture of the real and land cover.
- One pair of binoculars to distinguish different entities of the distant area such as different types of forest.