Warping of a spherical representation of image-based models on GPU
Jian Lin Zhu, Youquan Liu, Kai Bao, Yuanzhang Chang, Enhua Wu · 2009
Image warping techniques are frequently used to render 3D scenes from images with depth information for VR applications. In this paper, we first propose a spherical representation of image-based models call the Spherical Depth Image (SDI). With two Warping Equations, at runtime we then pre-warp the image onto a view-dependent plane to get an intermediate image, which is further rendered onto the target image plane using standard texture mapping. Compared with other representations, SDI is sampled uniformly and completely, therefore it can reduce much unnecessary rendering overhead and the resultant rendered image is hole-free. To speed up the computation and utilize hardware's rasterization function for image interpolation, we transport the pre-warping process into GPU's Vertex Shader. Besides, high quality rendering effect in Pixel Shader can also be achieved as traditional geometry based methods. Finally, we overcome the approach's limitation of viewing region, and design a real-time walkthrough system with LOD representations of the SDIs.