It sounds like you don't have a completely solid 3D volumetric image, like an (x,y,z) triplet for every single possible (x,y,z) location, and just have scattered data at a few of the possible locations. Perhaps you can use scatter3()?
scatter3(x, y, z, sizes, colors);
You'd set up colors to be different colors depending on the value of T. This would be like a 2.5D perspective rendering of a scatterplot of a bunch of points where the points colors depends on their temperature.
