CompuServe Messages

>>3D topo map to mesh… Do you want an easy way or a free way? If I had to do more than one, I'd definately look into one of the add-on's for Autocad. If you've got more time than money for new software, you can do it with 3DS. I made an effective mesh from topo data not long ago using a method I made up as I went. The method is a little convoluted to describe in words, but if you're interested… -Create curves for each elevation line in the shaper. (I actually scanned the map and manually traced the lines in CorelDraw, exporting as .AI) -Duplicate all lines and move the dupes out of the way (with SNAP!) for now. -Connect each contour line with an adjacent contour line at the edges of the map to create a series of closed shapes, with spaces between them. -With the duplicate made earlier, connect the contour lines again, but this time connect the pairs of lines such that what were spaces in the first set are now closed shapes in the duplicate set, etc. (Sort of the inverse of the first set.) -Select all the first set of shapes and loft or GetShape. -Select the second set and loft or GetShape, realigning them precisely. You should now have two objects, each filling in the "holes" left by the other. -Attach the two objects. Select all the vertices and weld. If lofted, detach the ground surface faces. -Now, the easy part <g>: one level at a time select all the vertices (by fence) for each discrete contour level, and /Vertex/Move "Selected" in a side view some distance vertically. For example, with an elevation range from 720-745 in steps of 5 ft, move the 725 line up 5 ft, etc. -Smooth 100% and edit as necessary. I found a little thoughtful application of Modify/Edge/Divide and Turn would fix those few faces that appeared unsmooth when rendered. This method worked very well and gave me an accurate mesh. I'm definately not saying this is the best way, but is certainly is cheap enough for a "government job". For about $150 you can get 3DSURF, but you'll have to create an ASCII file of coordinate data. I think about $1000 will get QUICKSURF which is supposed to work with Autocad to make this easy, but I don't have that one. And there are lots of professional software packages for big buck$ that work with surface data. Oh, there's another cheap and dirty manual technique if you've got the time: with a pencil <gasp!> draw a grid over the topo at whatever resolution you choose, and create a file containing a rectangular array of z-values, interpolated at each grid intersection point. I wrote and uploaded a program (MATHDX.ZIP) which will convert such an array into a surface mesh. That's all I can think of just now. Good luck! JKJ