Overview | Urban Sprawl | Fringe Area Development | Urban Agglomeration | Emerging Technologies | Relevant Links
A study on the application technique of remote sensing image for optimum route selection of the two-tract line railroad
2. Procedure
After preparation of images and data which is suitable for the purpose of this study, we've got to find the precise geographic coordinate of target district on the images. For this reason, we carried out Geometric Correction using GCP(Ground control point) to make three images, which are different from each other in resolution, fit into Geographic Coordinate and after that, carried out Close Ortho Correction using TM Coordinate, a geographic coordinate especially used for the current construction design. (1) Projection on Geographic Coordinate The basic map projection method for Ortho Correction Image Mapping is TM E002 Projection. And that is the map projection method being used by National geographic institute (NGI) for mapping. (2) Data Input The primary satellite image used in this study is the image from Arirang1 (hereinafter KOMPSAT). Purchase HDF formatted Pancro Band(1 channel, black-and- white) captured by EOC sensor and calculate the orbit information of the moving satellite. (3) DEM Creation Convert DXF formatted file of 1/5,000 Topographic Map to PIX formatted file. It's because the format of Ortho Engine, the image processing s/w, is PIX. After format conversion, you can create DEM. Picture 1. The results of 10m interval DEM creation by using vector of Contour Lines of target district (Yangsan, Kyongnam) Picture 2. The results of 5m interval DEM creation by using vector of Contour Lines of target district(Yongwol)  Figure 1. DEM of RGB expression (4) Ortho Correction Image Mapping) 1) Collecting GCP(Ground Control Point) To get precise ortho correction image, we collected coordinate values of GCP corresponding to specific points of satellite image using files of 1/5,000 Topographic Map and DEM files. In this study, once we found the location of a fixed construction such as a building roof, end point of a bridge and a corner of road, we could get TM coordinate and the altitude of the construction on digital map. Table 1. The results of Collecting GCP Table 1. Matching point of image and map for GCP
To confirm the matching accuracy of these GCPs, we evaluated the accuracy of GCP which was used for final close correction by using RMSE(Root mean square error) method. As the results, RMSE value of the above table turns out to be 5.08 m(0.74 pixel). In case the RMSE value for final one pixel is about 8 m, this result can be considered to be within the allowance. Since this RMSE value is below than the Spatial Resolution of Arirang satellite image before color-composite(6.6 m/1pixel), it's definitely considered to be within the allownace |