How to remove a class from the 3D viewer

Hi,

I am having some issues displaying my data in the 3D viewer. I have a CT scan of a rock which I have segmented using the trainable weka segmentation tool into three categories, fractures, vesicles, and background. I would like to display this in the 3D viewer and only show fractures and vesicles, without the background. Is this possible?

Cheers,
Max