A Method of Identifying and Extracting Craters Based on Lunar Surface DEM Data
- Paper ID
5826
- author
- company
- country
China
- year
2010
- abstract
This paper suggests a method of identifying and extracting automatically the craters from lunar digital elevation model (DEM) data, which can be directly applied in lunar craters research. On the lunar surface there are a lot of craters of various shapes and sizes. The identification of craters is the key and foundation of lunar research. The shape, distribution condition, mode, size and other parameters of crater and terrains around the crater can be combined to determine geological structure, ages and causes of formation of lunar surface for the study of lunar origin and evolution. All traditional methods of identification of crater are based on circumlunar satellite photographs or CCD (Charge-Coupled Device) pictures. Here the method developed by us makes use of DEM data to identify craters and extract features of craters. Traditional methods are greatly affected by solar illumination, solar altitude and other factors, but our method is not. The method based on DEM data has advantages because every point has an elevation data in the three-dimensional DEM. The topographic feature of crater is an annular mountain around a ‘pit’. The idea of the method is that elevation differences between annular ridge and surrounding terrain are used to identify craters and extract craters’ information. The algorithm of the method based on lunar surface DEM data is divided into three steps: (1) Extracting points of craters ridges. DEM points data of craters ridges are extracted and saved. The points include the information such as latitude, longitude and elevation. (2) Identification of crater. If the ridge points are distributed in a circle belt area, they are thought as a part of circle structure. (3) Determining the size and location of the crater. In order to get the information of crater, we try to fit these annular ridge points into round belts of changeable inner diameters and widths. A criterion is defined to check the fitness. If the belt satisfies the criterion, the crater and its characteristic parameters are determined and recorded. The inner diameter and width of the belt, the coordinates of geographical center and size of craters are stored into database for future research. Theoretical data and some practical DEM data of lunar surface proved that this method is feasible and reliable. The method may be applied in identification and extraction of craters under complicated conditions.