CompuServe Thread

#Goverment Job

10 messages in this thread
#143553From: Max J. Miller Jr.Dec 24, 1994 7:28 AM
My boss has some property in southern Ohio and I made him a 3d Topo map with extrude polylines in AME. This creates a stepped model and took all day to create. He wants a smooth model now, bless his heart. Whats the best technique for this. Is their some software that will generate the model. Merry Christmas
#143591From: rick lapidusDec 24, 1994 12:28 PM
Max, Schrieber has a 3d surf program which supposedly works great as an ipas in 3D Studio. Will generate terrain from autocad data. If you are not working from a file, it will randomluy generate hills. Sounds like you might want the autocad add on Landcadd Rick
#143625From: Max J. Miller Jr.Dec 24, 1994 10:02 PM
I'll check out Landcadd thanks max
#143652From: rick lapidusDec 25, 1994 2:07 PM
Max, Let me know how it works. I may send some contract work your way. Rick
#143821From: Dec 27, 1994 2:12 PM
Max: We use Schreiber's QuickSurf ACAD add-in for all our topo needs, has worked well for years! Greg Pyros
#143925From: bill "digr" lundeenDec 28, 1994 10:24 AM
Hi Greg, PMJI… I have the DEM Data CDROMS in USGS 3" format. I find when I bring a topo in that the vertical data is often not true to the live landscape it represents. Any chance you could do a test for me and tell me how a particular land feature comes out using Quicksurf? How about Devils Tower, Wyoming as a test? Coords 104.7-104.9 44.6-44.8. Bill.
#143955From: Dec 28, 1994 12:33 PM
Bill: I'd be happy to take a look at it, depending on how soon you need it! <g> Even better might be to send it to Chris Thomas [71031,3133] from Schreiber, who would be happy to test it out for you with QuickSurf and/or 3D Surf to see which would be better for your application! Let me know! Happy New Year! Greg Pyros
#143666From: John K. JordanDec 25, 1994 11:23 PM
>>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
#143676From: Max J. Miller Jr.Dec 26, 1994 6:51 AM
I started with Corel photopaint and scaned in the map. Lines were to broken for Corel Trace to connect, I used Acad rasterin command to import a PCX file. It was huge so I traced them with closed polylines. If I can import those Plines to the shaper can I use your technique? max
#143698From: John K. JordanDec 26, 1994 3:04 PM
I've never been happy with any autotrace program I've tried, so I always end up tracing by hand, ususally in CorelDraw, or right in the shaper if I only have a few lines. Also, I have very little experience with importing PLines – most of my Autocad exports have been DXFs of AME objects. But regardless of how you get the data into the shaper, the technique I described will work (it is actually easier than what it may have sounded like, but very time consuming, depending on how picky you are.) Also, I have the 3DSURF program here, which accepts an ascii file of x,y,z triplets. If you can extract that data from Autocad, I could try running it thru 3DSURF to make the mesh.