Using Civil 3D Surfaces in Other Programs

OK, I’ve been a bit of an unruly child – James has been bugging me about getting something up on the website to post. (He’s known about the 30 posts/30 days bit since March. No sympathy here. JW)

I’ve been getting ready for Tech Camp here in Sunny (windy?) Orlando, FL. Instead of writing yesterday, I did something unusual – I took a day off. Yes, I took my wife and little girl and spent all day (that phrase has a new meaning to me) in Disney World’s Magic Kingdom. My little girl was in awe of all the magic – all the princesses that she has adored since she was a baby have come to life! Me, I spent 30 minutes in one corner of the park investigating the drainage system during a downpour. The landscaping and engineering that go on there absolutely amaze me, and I got yelled at for having too much of an engineering mind (hey, why not plan your entire route through the park out in a logical, linear fashion???) So where’s my tip? After the jump!

Anyway, enough about my trip. I’ll try to have a full review as I go through the week, and may manage to post some tips and tricks during class. I’m here with my camera, so I’ll try to post some pictures of us hard at work as well (just to prove to everyone that it’s not a big vacation.) So this post (and trip) isn’t all fun, we’re going to learn something too – ever want to export a surface to another program (such as a GIS program) that might not use LandXML?

There are programs out there that may not use a LandXML surface. Some programs can utilize other file formats, such as DEM. See, DEM is a standard in surfaces, and can be utilized in a variety of programs. Map3D and Raster design can use a DEM file. Some of the ESRI software can make use of these files as well. In Civil 3D 2008, we now have the option to export our surfaces to a DEM file. This can be found in the Surface>Utilities>Export to DEM menu, and brings up the following dialog box:

As you can see, I can select any surface in my drawing to export, and set a coordinate system for that surface. In the export criteria, I specify a file name, export coordinate system (yes, this can do coordinate system transformations in this box), grid spacing (closer grids make more accurate surfaces, but MUCH larger files,) and how to determine the elevations on the grid. The help files define how these two options work:

Specifies how the elevations of the DEM file are determined from the exported surface. Select one of the following values:

  • Sample surface at grid point: Ensures that for each point along a DEM profile, the elevation is sampled from the selected surface.
  • Average: Ensures that for each point along a DEM profile, the elevation value corresponds to the mean elevation in a grid cell-sized region centered at this point.

So next time the GIS department asks for a surface file, tell them that you’d be more than happy to help them.

Have fun!

One comment

  1. Maylen Yee says:

    Hi! I want to use this feature but everytime I export to DEM, my laptop crashes. I have 3GB RAM, Core Duo processor and 128MB Video…By the way, my surface came from SHP contour lines which after some steps converted to Civil 3D surface…Can anyone help me?