Abstract



DGPS@Precision Image Correction

Ittipol Pha-ngen, ThongChai Srimuang, Jedsada Kirdsrilek
Space Technology Centre, Thailand


Abstract
Using advance radar and sensor technologies to improve the Earth observing satellites were proven to be beneficial in ordered to improve the economy, society and strengthen national security. Since the satellites image has wide varieties of bandwidths, cover large area and if combine radar technology or SARS the ability in viewing when having high percentage of cloud cover is increasing.

Another advantages since satellite image is consists of wide range of information, which can provide users with the modest and possibly latest information that can be obtain in sequence if required. Therefore satellite image is suitable in monitoring the national resources, environment and disaster. For example in Landsat7 have resolution of 15 and 30 meters, Radarsat-1 have resolution of 10 meters, Spot-5 have resolution of 2.5, 5 and 10 meters, while high resolution satellites such as IKONOS have resolution of 1 and 4 meters, and QuickBird-2 have resolution of 0.61 and 2.44 meters. Recently, the satellite image has been improved to give higher resolutions, also increase the level of applications among the users.

In general GISTDA’s Ground Receiving Station receives and process satellite image data in various forms of international standard products with radiometric and geometric corrections such as Systematic Geo-referenced Image Correction according to USGS standard within 250 meters resolution. But with this project the Differential GPS technique for collecting information of Ground Control Points (GCP), the satellite image data can be precise geometrically corrected and improved for positional accuracy. Technical elements of the study on DGPS@ Precision Image Correction of Landsat-7 is included the presentation about GCP survey, image processing with refinement the satellite attitude model by GCP marking were introduced.

As a result, the corrected image can be improved for positional accuracy within one pixel. The precision image data are generated in GeoTIFF format for Thai user community. The study is possible to implement for other satellite processing other than Landsat-7. The successful process will not only reduce the repletion of work among the organizations but also reduce the operations cost by provide the high accuracy satellite data in the same standard in the future.