topic Re: Export SRTM Dem file as 3d in Data Management Questions

Export SRTM Dem file as 3d

AdeliaLinburg — Tue, 05 Jun 2012 11:47:01 GMT

Hello all,
i have downloaded some SRTM Dem files here: http://dds.cr.usgs.gov/srtm/version2_1/SRTM30//srtm30
They are from the USGS site.

I would like to export them as 3d.

I have ran through a few tutorials online, eg
1) http://www.brocku.ca/maplibrary/procedures/3d_view/3dview.htm
2) http://prod.library.utoronto.ca/maplib/3D.pdf

But still don't get it.

Question:
1) so are the SRTM DEM files exportable to be viewed in 3d via Arcscene/ Arcmap?
2) how do you do it?

Thank you!

Best- Chloe

Re: Export SRTM Dem file as 3d

DanPatterson_Retired — Tue, 05 Jun 2012 13:42:30 GMT

Have you converted the data to an ESRI grid?

Re: Export SRTM Dem file as 3d

AdeliaLinburg — Tue, 05 Jun 2012 14:17:27 GMT

i think i did-
i converted the .dem into a .txt file (don't remember how i got it, tried many things...)

and i don't know how to proceed with the .txt file...

Sorry i am just starting to learn arcgis..

Best, C

Re: Export SRTM Dem file as 3d

EricRice — Tue, 05 Jun 2012 14:41:46 GMT

Chloe,

A USGS .dem file does not need to be converted to GRID format for use in ArcGIS. We read .dem files directly. Just open ArcScene and navigate to the raster and add it using the Add Data button. You probably will have to calculate statistics on the dataset before you can use it. Once it is in ArcScene, open the layer properties and go to the Base Heights tab. Set the layer to have its heights based on itself. Also, the data is most likely using a geographic coordinate system. I recommend projecting it into a projected coordinate system appropriate for the area to ensure that the X, Y, and Z values are all in the same unit of measure (feet/meters). If you do not want to project the data (use bilinear resampling if you do) you will have to set the vertical exaggeration in ArcScene to a really small number like 0.0003 for example, to account for the fact that your X,Y are in decimal degrees and your Z's are in feet/meters.

Eric