3D mesh from point coordinates

There seem to be a few posts referring to lisp routines that can create 3D meshes from files containing an irregularly distributed set of co-ordinates. Can anyone point me in the direction of such a lisp routine?

The aim is to model the wall of the inside of a cave from a real world set of coordinates (over 1000 x,y,z’s). I found a tool to do this using delaunay triangulation but I would prefer to use a rectangular mesh. I am also having problems with cave points joining across the cave where there should be open space. If anyone has any suggestions on how to edit or avoid this problem I would love to hear them?

Are any of these thoughts possible (even just in theory)? Create each side of the mesh along separate planes and somehow merge them later. Or create a solid object (points ->mesh ->solid) then create another mesh over the outside of the object, remove the inside so just left with a shell.

Any thoughts at all would be great

If you are using Land Desktop or Civil 3D you can create breaklines to keep it from triangulating across the "open space".

Thanks for your reply. I'm using AutoCad Map 3D. If creating breaklines is using break to split and remove sections of the object, then I think this can be done.

I wish I knew how to create a mesh of UTM coordinates in Autocad ?

This would be placed on a topographic map.

To Annabee referring to a cave be carefull if your points have both a floor and a roof then using Civ3D etc wil give funny models as they are only built from a plan point of view and would join roof pts with floor points. You really need a true 3d mesh generator that takes into account floor and roof and probably creates a true solid model representation of your "Cave" Also you wanted an answer in sq grids pretty sure its in Civ3D else create a grid of points and look up drape onto a surface should work.

To camposleandro are your points in a xyz text file ? If so lots of answers about creating meshes here.