glTF streaming from 3D repo to X3DOM

As Web3D technology advances, the need for delivering real-Time 3D content online has gained traction in the academic as well as commercial world. Various efforts have been made in creating a suitable transmission format for streaming of 3D assets over the Internet. Despite being accustomed to waiting for long periods of time for massive scenes to load in CAD editors, end users often expect an instant rendering on a web browser. An effective streaming transmission format, coupled with progressive encoding methods, is able to create a better interactive experience for the users. Most of the existing techniques are either domain specific, tying the users in on a particular rendering engine, or they are too general; resulting in extra processing at the application level. In this paper, we demonstrate a novel method of transmitting 3D assets in glTF format for high interoperability and scalability in 3D Repo. Firstly, we extend glTF with the ability to stream binary data buffers with a progressive encoding technique to increase performance and overall client interactivity. Next, we extend X3DOM for glTF support and introduce multipart optimization into glTF as a way of grouping multiple meshes together which significantly reduces the number of network requests as well as draw calls. Finally, we investigate memory management protocols and devise a novel GraphicsMemoryManager suitable for streaming on top of X3DOM in order to render models that otherwise would not fit available video memory

Spatial data structures for accelerated 3D visibility computation to enable large model visualization on the web

The visualization of massive 3D models is an intensively examined field of research. Due to their rapidly growing complexity of such models, visualisation them in real-time will never be possible through a higher speed of rasterization alone. Instead, a practical solution has to reduce the amount of data to be processed, using a fast visibility determination. In recent years, the combination of Javascript and WebGL raised attention for the possibility of rendering hardware-accelerated 3D graphics directly in the browser. However, when compared to desktop applications, they are still fighting with their disadvantages of a generally slower execution speed, or a downgraded set of functionality. We demonstrate the integration of spatial data structures, computed on the client side, using latest technology trends to mitigate the shortcomings of the 3D Web environment. We employ comparably small bounding volume hierarchies to accelerate our visibility determination, as well as to enable specific culling techniques. This allows for an interactive visualization of such massive 3D data sets. Our in-depth analysis of different data structures and environments shows which combination of data structure and visibility determination techniques are currently the best fit for the Web