Image based representation for 3D content delivery

• Main Author: Chew, Boon Seng
• Other Authors: Chau Lap Pui
• Format: Theses and Dissertations
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/50767
• Institution: Nanyang Technological University

The evolution of the Internet from a basic communication tool to a content driven community pushes the development of 3D virtual world interaction and exploration to a new height in recent years. This is a significant trend seen from the rapid growth in virtual world community and applications like 3D online gaming and content sharing. With the increasing demand for high quality 3D contents, interactive avatars and realistic virtual world environment, there is an urgent need to address the effective representation and smooth delivery of such information across networks given the erratic nature of the Internet and wireless channels. This thesis focuses on the theoretical analysis and the introduction of efficient encoding techniques for static 3D models and dynamic Virtual Character Animation data. First, a new image format for the representation of 3D progressive model is proposed. The powerful spectral analysis is combined with the state of art Geometry Image (GI) to encode static 3D models into spectral geometry images (SGI) for robust 3D shape representation. Based on the 3D model's surface characteristics, SGI separated the geometrical image into low and high frequency layers to achieve effective Level of Details (LOD) modeling. For SGI, the connectivity data of the model is implicitly encoded in the image, thus removing the need for additional channel bits allocated for its protection during transmission. We demonstrated that by coupling SGI together with an efficient channel allocation scheme, an image based method for 3D representation suitable for adoption in conventional broadcasting standard is proposed. Second, two encoding schemes that focus on the efficient representation and compression of the Virtual Character Animation (VCA) are shown. The proposed Scalable virtual character animation (SVCA) demonstrates a technique for transmitting level of details motion sequences for virtual character animation, focusing on the structural coherence characteristic of the virtual avatar. Virtual Character Animation Map (VCAM) is introduced next to address the limitation in SVCA to further improve the compression efficiency of the VCA data. Third, a novel concept Virtual Character Animation Image (VCAI) is proposed. The VCAI jointly considers the structural and temporal coherence of the VCA to achieve compression and scalability of VCA data making it suitable for progressive transmission applications. A modified motion filter (MMF) is further proposed to minimize the visual discontinuity in VCA's motion due to the quantization and transmission error.