trouble smoothing DEM for contour lines

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12-12-2017 04:40 PM
AliciaGorman
New Contributor

Hello all,

I am trying to make smoother contour lines for a map, but none of the usually recommended methods of smoothing a DEM (according to google) are working for the file I have. I have tried smoothing and simplifying the contour lines produced from the DEM, but get a bunch of orthoganal straight lines. Then I read that it is really best to smooth the raster anyways, so I tried boundary clean and majority filter but when I select my raster file to input I get an error that says "Error 000864 Input raster: The input is not within the defined domain. Error 000863: Invalid GP data type." I am inputting a raster though, so I don't understand what the problem is. I am a beginner here though, so maybe there is something really obvious I am missing?

To give a little bit of background, I created this DEM by drawing paths in google earth, saving as .kml, converting to .csv using TCX Converter, then cleaning up the file and saving as .xslx and importing into ArcMap, then exporting as a point shapefile. I don't know if something about the way I created my DEM is making it "odd." 

Below is a picture of the contour lines that I currently have.

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7 Replies
DanPatterson_Retired
MVP Emeritus

the main body survived well. the circular fiddly bits are strange... If you want to remove those, I had recently recommended calculating the length of the contours and then remove those below a certain length threshold... 

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AliciaGorman
New Contributor

Thank-you! I will try that. Maybe that will smooth things a bit too.

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XanderBakker
Esri Esteemed Contributor

Normally to smooth a DEM you would use a Focal Statistics—Help | ArcGIS Desktop with the MEAN as statistics type. The larger the neighborhood, the bigger the effect. Reading the way you generated the DEM, makes me wonder what it looks like. To evaluate the quality visually I recommend creating a Hillshade—Help | ArcGIS Desktop and share a screen shot of it. 

To smooth lines, there is a tool Smooth Line—Help | ArcGIS Desktop 

AbdullahAnter
Occasional Contributor III
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SteveLynch
Esri Regular Contributor

Smoothing the contour lines after the fact can result in overlapping/intersecting lines, be careful.

I would suggest that you rather smooth the raster, from the Contour tool's help...

DanPatterson_Retired
MVP Emeritus

I assume that the closed-loop hashed pattern areas are what wants to be removed, hence my recommendation.  The focal statistics on the dem may remove these artifacts, but probably not, so a combination of the recommendations may work