Real-time watercolor illustrations of plants using a blurred depth test

We present techniques to create convincing high-quality watercolor illustrations of plants. Mainly focusing on the real-time rendering, we introduce methods to abstract the visual and geometrical complexity of the original 3D plant models that are obtained from the photorealistic rendering. Additionally, we integrate detail layers to emphasize the structure, the texture, and the lighting. We distinguish between particle based, texture based, and line stroke based detail primitives, which provide a wide application range for the individual tree and plant models. To support smooth transitions and the frame-to-frame coherence during an animation, we introduce a so-called blurred depth test to perform depth comparisons. This blurred depth test is utilized for the visibility computations of the detail primitives and for the creation of a soft shadowing effect. With our techniques, we create an appropriate lighting and shadowing of the scene, and achieve a high frame-to-frame coherence. For the final watercolor appearance, we apply a formerly published approach that is implemented using hardware shaders.