Robotic Rendering of Oriental Ink Paintings with Spatial Awareness

Abstract

Enabling robots to imitate artists who observe objects in the 3D world and physically draw them in a specific style is a challenging problem. Shuimohua (Sumi-e) is a typical non-photorealistic oriental ink painting art that uses simple ink, water and brush to paint and convey poetic imagery. Although digital rendering of non-photorealistic paintings has been extensively studied, physical rendering of stylized painting from 3D space is still a challenge because it requires to consider the abstraction process of vectorized strokes with various styles in physical environment. In this paper, we propose a robotic rendering approach for physically drawing oriental ink painting from 3D shapes, and aim to mimic the painting process of a real-world artist using binocular vision to estimate 3D scenes. By referring to the artists' drawing habit, first, we extract expressive contours as drawing outlines and vectorize the contours to polylines. Next, the polylines are converted to line strokes with varying thicknesses by considering clamped B-spline fitting and isophote distances. In order to generate a typical dot shading effect, an oriented Poisson disk sampling approach is proposed to create dot strokes to depict the internal features of the 3D models. Finally, we build an ink gradient model and map the coordinates of the strokes to a robotic arm, and a control method of guide rails is proposed for robotic painting on large canvases.