Once imported, simply select what you want to measure and the dimensions will be displayed along the top of the AC3D interface. This could be the whole lot or perhaps two vertices, one on the 'ground' and one at the maximum.
Bas-relief-from texture (Tools menu) might be useful if you can get your data into image form. See here for more info:
https://www.inivis.com/supercoldmilk...basrelief.html