Real-time Volume Rendering and Tractography Visualization on the Web

In the field of computer graphics, Volume Rendering techniques allow the visualization of 3D datasets, and specifically, Volume Ray-Casting renders images from volumetric datasets, typically used in some scientific areas, such as medical imaging. This article aims to describe the development of a combined visualization of tractography and volume rendering of brain T1 MRI images in an integrated way. An innovative web viewer for interactive visualization of neuro-imaging data has been developed based on WebGL. This recently developed standard enables the clients to use the web viewer on a wide range of devices, with the only requirement of a compliant web-browser. As the majority of the rendering tasks take place in the client machine, the effect of bottlenecks and server overloading are minimized. The web application presented is able to compete with desktop tools, even supporting high graphical demands and facing challenges regarding performance and scalability. The developed software modules are available as open source code and include MRI volume data and tractography generated by the Diffusion Toolkit, and connectivity data from the Connectome Mapping Toolkit. Our contribution for the Volume Web Viewer implements early ray termination step according to the tractography depthmap, combining volume images and estimated white matter fibers. Furthermore, the depthmap system extension can be used for visualization of other types of data, where geometric and volume elements are displayed simultaneously.