voxelizer | A GPU triangle mesh voxelizer using the geometry shader | Graphics library

NOTE: THIS QUESTION HAS BEEN DRASTICALLY EDITED FROM ITS ORIGINAL FORM

I am attempting to create a logarithmic raytracer by implementing an oct tree data structure combined with voxelization to achieve fast ray tracing.

Currently I am having issues with the ray collision detection.

The expected output should be the voxelized stanford dragon with its normal map.

Currrently the issue is that some regions are transparent:

The full dragon:

Transparent regions:

From these images it should be clear that the geometry is correct, but the collision checks are wrong.

There are 2 fragment shaders involved in this process:

I am trying to use vtkImageReSlicer to extract a 2d slice from a 3d vtkImageData object. But I can't seem to get the recipe right. Am I doing it right?
I am also a bit confused about ResliceAxes Matrix. Does it represent a cutting plane? If I move the ReSliceAxes origin will it also move the cutting plane? When I call Update on the vtkImageReSlicer, the program crashes. But when I don't call it, the output is empty.

Here's what I have so far.