Ridge-Valley-Guided Sketch-Drawing From Point Clouds.

Sketch-drawing is one of the simplest and most direct means to illustrate 3-D objects. It can not only present geometric features, but also greatly facilitate us to identify and understand the object. This paper presents a simple yet effective tool to generate view-dependent sketch-drawing from point clouds. First, we extract the ridge-valley lines in geometric regions by utilizing their curvature; meanwhile, we extract the contours of point clouds based on the object view-dependent; the obtained ridge-valley lines and contours are optimized and fused to describe the geometric features of the object. Second, we apply the change models of line thickness diffusion based on angle and depth to finish the line thickness variation. Finally, the shadow region of sketch-drawing is achieved by using the shadow generation model based on line density and gray value. Experimental results show that our proposed method can effectively complete the object sketch-drawing simulation from point clouds. Furthermore, our method is more flexible and robust than the existing algorithms; it does not require the preprocessing on the input point clouds.