I have a DEM and I want to create a DTM from that DEM. Is it possible to do this in ArcGIS?

  • Please read about DTM and DEM possible here: what-is-the-difference-between-dem-dsm-and-dtm.
    – dof1985
    Apr 11 '15 at 15:53
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    @Shawty; Can you explain the purpose of the edit? Since it ignores the fact that both terms are mostly synonymous. Thus, further clarification is needed to explain what exactly the P would like to change. Did the addition of the term "file-format" changed something?
    – dof1985
    Apr 11 '15 at 16:27
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    Where did "I don't know a great deal about ArcGis" come from -- a previous deleted comment?
    – Erica
    Apr 11 '15 at 16:38
  • If you have to use ArcGIS, why do you want a dtm file? .dtm is typically a Microstation file, and as far as I know there isn't a way for Arc to work with or write one out. .dem files are typically another delimited text format that Arc has specific tools to read in and convert to raster. Part of the problem is the extensions can be used on files with different internal structures that may not be compatible across software. Related old Esri forum post: forums.esri.com/Thread.asp?c=93&f=995&t=107291 What exactly are you trying to do? Create a surface from a .dem file? DEM to Raster tool.
    – Chris W
    Apr 11 '15 at 18:44
  • Hey folks, just hold on a second there.... Everyone seems to be under the impression I asked this question. I did not, the question was poorly worded and in the spirit of stack exchange being what it is, I decided to re-word it so that it read better. Now if folks have a problem with that, message me privately but don't start picking fault with my good intentions in public. As to dof's comment, yea, simply decided to rewrite it to mean the same thing so that it read better than it did originally.
    – shawty
    Apr 13 '15 at 15:05

DTM is used interchangeably with DEM sometimes, but since you are asking to go from DEM to DTM then you must have something specific in mind.

DEM format is normally a raster where each pixel's value represents an elevation.

DTM sometimes refers to non-raster formats like a Triangulated Irregular Network (TIN). If that's what you want, you could use the ArcGIS 3D Analyst extension to build a contour layer (use "Contour" tool) from the DEM, and then create a TIN (use "Create TIN" tool) from the contour feature class. (http://www.esri.com/news/arcuser/0101/avfiles/lesson6.pdf)

Sometimes people use "DTM" to mean "bare earth surface". If you want to do that then the answer is "no". There is no tool in ArcGIS that automatically detects and removes things like buildings from a DEM. If you have a DEM that was derived from a point cloud (like LiDAR) then you would need to use the original point cloud to generate a bare earth surface.

Working in ArcGIS, you might want to use a Terrain Dataset instead of just a TIN. You still have to go through the steps to convert the DEM to a vector format. Once you have added data sources to the Terrain Dataset the TIN is as needed. The starting point for terrains is to use the New Terrain wizard. (One way to do this: in ArcCatalog, create a file geodatabase, then create a feature dataset inside that, then select the feature dataset and use "File->New->Terrain") Using the wizard will help you define data sources and pyramid levels.

  • A DTM is a 'simplified approximation', like Chris said it's usually used in Microstation or other CAD packages that don't have the processing power, but of what? The surface or the topography? You can make one from breaklines and spot elevations but selecting them can be quite time consuming to do properly. Have a read of forums.esri.com/Thread.asp?c=93&f=1734&t=209286#630434 about the DTM format which is fairly easy to write out with some basic python after the simplified approximation is defined. Apr 13 '15 at 1:01

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