How to create a 3d image from 2d slices of a rock core?

Hello, I have a bunch (thousands) of 2D CT scan slices(grayscale) of a single rock core.The slices are from the top of the core to the bottom. I want to combine the images into one 3D image to create a digital core. I used cat(3,N1....NN) but it just stacks the images.Can someone please help me. I want to later convert the image to binary (or I can do it on the 2Dimage) so that one represents solid and 0 represents pore so that I can be able to calculate the pore volume of the rock.

[José-Luis]

Sounds like you need to interpolate. Plenty of ways of doing that. Kriging?

[Xiaoli]

Thanks