How can I sample a 3D volume using vtk Fixed Point Volume Ray Cast Mapper

Hello VTK users,

I am doing some quantitative work that requires that I sample every voxel along parallel rays that pass through a 3D volume, with (ideally) one ray passing through each of the voxels facing the camera. For example, if the volume has dimensions (X,Y,Z), then I’d need one ray for each (x,y) coord sampling all positions z: [0,Z-1].

I am trying to achieve this while rendering with the vtkFixedPointVolumeRayCastMapper. I’ve modified this mapper to not use space leaping as it was originally intended and the through-plane sampling is achieved by specifying the mapper’s sampling distance as the z-spacing. My issue has been that not all (x,y) positions are being sampled. I’ve examined the start points of each ray and confirmed that specific columns positions are not being sampled. I can force this to happen by adjusting the Image Sampling Dsitance to be very small, e.g. 1.0, but as each of the volume’s voxel encompass many image pixels, each (x,y) coords is being sampled up to ~6 times.

Can any suggest an approach for determining the Image Sampling Distance that will minizing redundant sampling but ensure that all (x,y) coords are hit?

Please let me know if I’ve been unclear on any of these details.