Question on generating elevations for contour lines

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06-02-2021 12:17 PM
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JasonShim
New Contributor II

Hi,

I have generated contour lines from a merged DEM file. The Merged DEM (DEM 1 + DEM 2) has elevation levels ranging from ~27m to 64m. However, the elevation levels for the Contour_DEMMERGE.dat raster file I've created does not show the correct elevation. Elevation levels should be ranging from ~27m to 64m similar to the merged DEM. My question is how do I generate elevation levels for the Contour_DEMMERGE.dat raster file to match the elevations in the DEM?

Thank you.

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DanPatterson
MVP Esteemed Contributor

some steps in producing the map would be useful. 

Does the merged feature class have the elevation values?

What did field did you use to produce the output?

 


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JasonShim
New Contributor II

Hi Dan,

I produced the contour map using the Raster Functions-Contour Properties Tool as shown in the attached file. I entered DEMMERGE.dat as the Input raster. Yes, the merged DEM's (DEMMERGE.dat) have elevation values assigned to them. However, after I hit "Create Layer", the contours show on the map, however there are no elevations assigned to them. My question is: how do I generate elevations for these contour lines?

 

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DanPatterson
MVP Esteemed Contributor

When you converted to raster, you should have been asked for the "field" to use.  You should have used the field containing the elevation/Z values.... it looks like you used some ID field

A tip... use screen grabs (png, jpeg etc) to post images... *.docx files take time to process and load, images can be inserted within the question (camera tool on the post toolbar) so no loading is needed.


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JasonShim
New Contributor II

Dan,

In Raster Functions-Contour Properties Tool window, it does not ask me for a "field" to enter. So, I'm not exactly sure what field are you referring to? Can you share a screenshot?

JasonShim_0-1622724198605.png

 

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DanPatterson
MVP Esteemed Contributor

Did you go from polylines straight to contour?

I have used Polyline to Raster (Conversion)—ArcGIS Pro | Documentation with the value field as elevation/Z if you digitized the contours and assigned an elevation to each.  From there you can try the contour function.


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JasonShim
New Contributor II

No, Dan. The contour lines were not digitized. They were generated from the merged DEM file I showed you earlier. Here are the steps as to how I generated the contour lines.

1. Click Analysis tab

2. Click Raster Functions

3. Click Surface

4. Click Contour

JasonShim_2-1622744555700.png

 

JasonShim_3-1622744582265.png

 

 

JasonShim_1-1622744343925.png

 

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DanPatterson
MVP Esteemed Contributor

ahhh now I see.  I didn't scroll far enough in your original to see the 1, 2 values

Contour function—ArcGIS Pro | Documentation

The contours generated from the elevation dataset are rasters with a value of one (1). The bold index contour has a value of two (2). Use Identify to display the elevation value of the contour based on the source elevation layer, which will return the elevation of the contour, point, key features, and spot heights on the maps and images.


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