How to create contours from a DEM image service

berniejconnors

Hello, We are publishing a bare earth DEM with a 1 metre pixel as an image service.  Currently running ArcGIS Server 10.7.1.  I want to automate the process to assist my users in creating contours from the DEM  image service.  The process would begin with the user selecting a polygon from our parcel map service and end with the user downloading a vector data set of contour lines with an extent that matches the parcel's bounding box.

We have already done something similar to allow our users to grab a small patch of the DEM raster that matches the bounding box of a parcel.  We did that with a bit of Arcade to build a URL for the image service that exported a small patch of the DEM raster.  The Arcade script lives in a pop-up window in an AGOL web map.

Any suggestions?  You can find our DEM image service here - https://geonb.snb.ca/image/rest/services/Elevation/DEM_Raw_MNE_Brut/ImageServer

Thanks,

Bernie.

ThomasHoman

Hello,

Since you already have the ability to extract a small piece of the DEM, you could push that into a piece of Python that generates the contours via 3DAnalyst Contour tool - https://pro.arcgis.com/en/pro-app/latest/tool-reference/3d-analyst/contour.htm and returns the data to the user as a gdb. This, of course, is predicated on have the 3DAnalyst tools licensed on the machine doing the work.

An alternative to the 3DAnalyst extension licensure can be accomplished with the python GDAL library. https://hatarilabs.com/ih-en/how-to-convert-a-raster-to-contours-with-python-and-gdal-tutorial 

A third option would be to preprocess the DEM to a few expected contour intervals and then allow the user to extract the data much like you already have with DEM AOI tool. This would avoid the resource overhead of the DEM to contour processing.

Regards,

Tom