topic Re: DEM to 3D Elevation Contours in AutoCAD Map 3D Forum

DEM to 3D Elevation Contours

bcicio — Mon, 24 Feb 2020 15:52:07 GMT

Admittedly, I do not know my way around Map 3D as I usually work in Vanilla AutoCAD. I have connected the data and added a DEM.TIF file, but the .TIF appears to be a flat image even though I have added a color style to the various elevations and the colors do vary. I can create contours, but even those appear to be all zero elevation when viewed from the front or sides. However, as I rotate the object using the 3DOrbit command, I can see a 3D wire frame ghost image of a 3D mesh surface -- so there is obviously a 3D mesh that has been generated in the drawing. When I exit the 3DOrbit command, it all goes back to just a flat 2D image. So my first question would be how do I display that mesh? And second would be how do I create 3D contours with elevation values based on it? Interestingly, if I import that DEM.TIF into Civil3D, it tells me that the points have no z-values. (But, again, Map3D shows a ghosted mesh during 3DOrbit). Thanks for any pointers. --Bill

Re: DEM to 3D Elevation Contours

ChicagoLooper — Mon, 24 Feb 2020 16:44:44 GMT

You can can topographic contours from your DEM in sdf format. The sdf format is a vector, not a raster. The sdf can also be imported so they'll be AutoCad polylines. As you can tell, obtaining usable CONTOURS from a DEM is a two-step process, not a simple click-and-I'm-done deal (usable means you can use them to create a surface).

To Create Contour Lines:

Right click PratoSite08AUG in the Map Task Pane then select Create Contour Layer from the shortcut. You'll be presented with options to select contour interval, major contours, elevation in feet or meters, and the folder where you wish to save the contours (in sdf format).

Using MAPIMPORT command on the sdf contours, you can then create, or convert them to polylines. Be sure to 'Create Object Data" during the import so your contours will have elevation 'data.' This data is important b/c it can be use to 'elevate' or raise your contours from z=0 to their proper elevation using the Query and Alter Properties functions.

By using QUERY and ALTER PROPERTIES functions together, the contours will be 'raised' and once raised can be used to build your surface. Back in August 2011, Brian Hailey did an excellent job explaining this procedure. You can read about it >>HERE<<.

Re: DEM to 3D Elevation Contours

bcicio — Mon, 24 Feb 2020 16:51:06 GMT

Thanks, ChicagoLooper! I appreciate it.

Re: DEM to 3D Elevation Contours

jmorrison2Q85R — Tue, 30 Mar 2021 18:58:50 GMT

@ChicagoLooper Maybe I'm a little slow, but can you spell out how to use the Query and Alter Properties functions to change the elevation of the contour lines to match the object data obtained from MAPIMPORT?

Re: DEM to 3D Elevation Contours

jmorrison2Q85R — Tue, 30 Mar 2021 19:26:41 GMT

Looks like I found it myself...maybe a little more convoluted than I'd like.

Importing a shapefile that contains Z values representing the elevation is only 2D in AutoCAD Map 3D | AutoCAD Map 3D 2019 | Autodesk Knowledge Network

Re: DEM to 3D Elevation Contours

O_Eckmann — Wed, 31 Mar 2021 07:49:34 GMT

Hi,

If you prefer a simplier solution, I've written a plug-in to treat countour lines, and another generic solution to apply any CAD/OD information to OD/CAD property

In this discusion : https://forums.autodesk.com/t5/autocad-map-3d-forum/applications-for-object-data/td-p/9336333/page/2

Message 25 : explanation of my plug-in, and in message 48 I've updated ZIP file.

Olivier

Re: DEM to 3D Elevation Contours

braudpat — Fri, 02 Apr 2021 11:56:58 GMT

Hello

An other solution based on a Lisp routine "OD2DXF38" ...

Assuming you have 2D Plines (often coming from a MAPIMPORT) with an OD (Object Data)

which is the Z / Altitude / Elevation !?

"OD2DXF38" changes the Elevation (DXF Code 38) of 2D Plines ...

The Health, Bye, Patrice