We present stroke transfer, an example-based synthesis method of brushstrokes for animated scenes under changes in viewpoint, lighting conditions, and object shapes. We introduce stroke field for guiding the generation of strokes, consisting of spatially varying attributes of strokes, namely, their orientations, lengths, widths, and colors. Strokes are synthesized as the integral curves of the stroke field. In essence, we separate elements that constitute the artistic stroke into style-specific transferable elements and instance-intrinsic ones. To generate the stroke field, we first compute a set of vector fields that reflect the instance-intrinsic elements and then combine them using style-specific weight functions learned from exemplars, with the weights computed in a proxy feature space shared among a variety of objects. The rendered animation using our method captures time-varying viewpoint, lighting conditions, and object shapes, as well as the artistic style given in the form of exemplars.

Non-photorealistic rendering, stroke-based rendering, examplebased, stroke transfer, vector field generation

We thank the anonymous reviewers for their insightful suggestions and discussions. This work was supported in part by a grant from JST FOREST Program, JPMJFR206R, Japan, a JSPS Grant-in-Aid for Scientific Research (A) 18H04106, Japan, and a JSPS Grant-in-Aid for Scientific Research (C) 22K12051, Japan.