Objectives The representation of landform features is an important part of cartography and the relief shading is the main tool for effectively expressing the 3D landform on the two-dimensional plane. The hill-shading produced by the existing method is not artistic enough, and the expressiveness of the terrain needs to be improved. In this regard, a hill-shading generation method based on ResUNet is proposed.
Methods First, the high-quality manual relief shading and the corresponding digital elevation model (DEM) data are processed, such as resampling, unifying coordinate system, cropping, etc., to construct the shading‐DEM sample image pairs. Then the parameters of the proposed DEM-shading conversion model are learned from the sample data. Finally, the DEM of any area is input into the model, and the output results of which are spliced using alpha blending to form the relief shading.
Results The experimental results show that the relief shading generated by the proposed method is improved in artistry and terrain expressiveness and can closely match the quality of the manual relief shading, due to the “Swiss style”, the effective terrain generalization and the contrast optimization on both sides of the ridges. Compared with U‑Net, the proposed model is more adaptable to DEM of different resolutions, and can generated shading with better visual effects.
Conclusions The proposed method can effectively improve the artistry and terrain expressiveness of the hill-shading.
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