||Volume Rendering is the image reconstruction from three dimensional volumetric datasets. For medical applications it is acquired by specific scanning procedure like Magnetic Resonance Imaging or Computed Tomography. In engineering it is often the result of scientific simulations and computations.
In the simplest case the input data contains only one value per voxel, which in medical diagnosis is the density. The rendering process is accomplished by one of the established methods, in our case Direct Volume Rendering technique - Ray Casting. For every pixel in the image, the volume is traversed in search for the presence of object to be visualised, encountered samples are looked up in the given transfer function and composited according to some specified formula.
The results of many research activities produce however volumes containing multiple values for every voxel. This Master Thesis presents experiments and a new method that allows direct visualisation of more than one scalar value, excluding colour manipulations.
The solution was achieved by normal vector modification for lighting purposes, similar to bump mapping, yet moved into additional dimension. We created a normal map in 3D, containing spheres (bubbles) filled with normal vectors. The 3D bump map contribution is filtered and modulated with respect to the values of the additional scalar parameters. The results create an illusion of rash on the rendered objects and indicate the presence and the quantitative visualisation of extra data.
The program developed for this project, was implemented with the use of the most recent Shading Language GLSL, exploiting fantastic features offered by bleeding edge GPUs. Usage of this new technology.