Structured multi-scale reconstruction method suitable for regular grid DEM

Abstract

The invention provides a structured multi-scale reconstruction method suitable for a regular grid DEM. The method comprises the first step of extraction and structured organization of valley catchments, the second step of valley selection and catchment combination, and the third step of constraint interpolation based on the combined catchments for generating a new DEM removed from secondary valleys. Based on experimental comparison, positive and negative landforms are cut down to the same extent no matter how large the valleys and the ridges are in a traditional resampling method and a filtering comprehensive method, and the retention of the geographic features is not taken into account; however, once the structured multi-scale reconstruction method suitable for the regular grid DEM is adopted for integration, the contour line curves representing the secondary valleys show a group deletion effect, and the contour line curves representing major valley sources are well retained, and the effect is close to the manual integration effect of a specialist.

Description

technical field [0001] The present invention relates to a terrain synthesis method, specifically a DEM (Digital Elevation Model, English full name is Digital Elevation Model, hereinafter referred to as DEM) synthesis method using the link between the catchment area to connect the valley entity and the grid point. Background technique [0002] Traditional map synthesis is the process of reducing a large-scale map to a small-scale map, which is the core issue of cartography. DEM synthesis, that is, deriving lower-resolution DEM data from higher-resolution DEM data, is a key technology for multi-scale terrain expression, analysis and application. The synthesis process needs to meet the basic constraints of terrain synthesis, that is, delete secondary Topographic structure features, retaining the main topographic structure features, DEM synthesis is a geographical feature-oriented, structured spatial information abstraction process, rather than simple data compression, the tradi...

AI Technical Summary

Problems solved by technology

[0004] At present, the terrain can be roughly classified into three categories, namely ① global filtering method based on smoothing filter. The global filtering method achieves a smooth effect by eliminating the high-frequency part in the original data. Typically, there are low-pass filtering method and wavelet analysis method. This type of method does not discard or simplify the specific geomorphic structure, and is suitable for comprehensive tasks with small scale spans. However, when the scale changes greatly, the comprehensive results often deviate from the real topographic structure, and cannot achieve the goal of "retaining the main form and discarding the secondary". The combined effect of "to fluctuate"

② Selective filtering methods to eliminate secondary data points, such as hierarchical method, important point method, tolerance method and three-dimensional Douglas method, etc., the basic idea is to define the importance of DEM points according to the neighborhood information, and retain high importance In the simplification process, this type of method lacks the control of the overall terrain structure characteristics, and the comprehensive results are prone to the phenomenon of flattening of mountains and uplifting of valleys, resulting in the distortion of the overall landform skeleton to a certain extent.

③Structured synthesis method based on topographic structure lines, grouped contour line synthesis method proposed in "Test of Grouped Contour Lines and Grouped Synthesis of Topographic Map" (Journal of Wuhan University of Surveying and Mapping Science and Technology, 1993, Fei Litu, etc.) , the basic idea is to first extract the terrain structure lines implicit in the complex contour graphics or regular grid DEM, and then complete the simplification of groups of contour lines or the regular grid DEM based on the choice of terrain structure lines Filling, so as to realize the synthesis and simplification of the terrain, this kind of method considers the global structure of the terrain, reasonably uses the terrain structure line, and avoids the distortion of the topography to a certain extent, but the contour line associated with the terrain structure line is curved Groups and regular grid blocks are often difficult to establish automatically, and need to be supplemented by manual identification

Images