Question

I have been brought in on a project where I need to render a 3D volume from a series of images of the volume. The images have been created by a couple of techniques such that they are vertical slices of the object in question.

The data set is similar to this question, but the asker is looking for a Matlab solution.

The goal is to have this drawing be in something near real time (>1Hz update rate), and from my research openGL seems to be the fastest option for drawing. Is there a built in function in openGL render the volume in openGL other than the following psuedocode algorithm.

foreach(Image in Folder)
     foreach(Pixel in Image)
        pointColour(pixelColour)
        pointLocation(Pixel.X,Pixel.Y,Image.Z)
        drawPoint

I am not concerned about interpolating between images, the current spacing is small enough that there no need for it.

Answer 1

I’m afraid if you’re thinking about volume rendering, you will need to first understand the volume rendering integral because the resultant color of a pixel on the screen is a function of all the voxels that line up with it for the current viewing angle.

There are two methods to render a volume in real-time using conventional graphics hardware.

1. Render the volume as a set of 2D view-aligned slices that intersect the 3D texture (proxy geometry). Explanation here.
2. Use a raycaster that uses programmable graphics hardware, tutorial here.

This is not an easy problem to solve – but depending on what you need to do things might be a little simpler. For example: Do you care about having an interactive transfer function? Do you want perspective views, or will orthographic projection suffice? Are you rendering iso-surfaces? Are you using this only for MPR-type views?