topic Re: How do I get areas with a certain elevation out of a raster file? in ArcGIS Spatial Analyst Questions

How do I get areas with a certain elevation out of a raster file?

andreabarrueto1 — Mon, 23 Jun 2014 11:41:27 GMT

I have SRTMs for a country and I need to get a layer with the different altitudes that i can use later on for the weighted overaly:
Following are the classes:
0m-1100m
1100-1500m
1500-1800m
1800-2500m
2500-2800m
2800-3000m
3000-8000m
I tried reclassify, did not work. For visuals I can display the wished classes with the contour polygon, however, I cant really use it later with other polygons (when I want to intersect for the weighted overlay).

How can I calculate (i tried raster calculator but did not get anywhere) the needed elevation polygons? I have all extensions.

Thank you.

a.

Re: How do I get areas with a certain elevation out of a raster file?

toddsams — Mon, 30 Jun 2014 20:41:14 GMT

There are a variety of ways you can do this, but one that jumps to mind is:

You can use "Set Null" to set elevations outside of those bounds to Null. Then, convert the final rasters (one for each elevational band) to polygon files using "Raster to Polygon".

Re: How do I get areas with a certain elevation out of a raster file?

andreabarrueto1 — Tue, 01 Jul 2014 07:26:55 GMT

thank you. do you mind telling me with a bit more details how i can do that?

thanks.

a.

Re: How do I get areas with a certain elevation out of a raster file?

DanPatterson_Retired — Tue, 01 Jul 2014 07:38:27 GMT

reclassify should work and you can assign the weights directly to the elevation classes. What do you mean it didn't work?

Re: How do I get areas with a certain elevation out of a raster file?

toddsams — Tue, 01 Jul 2014 13:17:35 GMT

I agree with Dan that Reclassify should work.

I am not able to get into detailed descriptions of how to use these tools. ESRI provides a fair amount of documentation associated with the tools found in the toolbox. Be sure to read all of the help documentation associated with each tool prior to running it.

Re: How do I get areas with a certain elevation out of a raster file?

andreabarrueto1 — Wed, 02 Jul 2014 07:10:45 GMT

Thank you very much. It worked. Now what I have to do is choose the classes through symbology before using reclassify. In that way i could choose the classes in reclassify (which was not possible before).

Best wishes,
a.

Re: How do I get areas with a certain elevation out of a raster file?

JeffreySwain — Wed, 02 Jul 2014 10:48:07 GMT

I would also look into the CON tool to simply select all but the value you are looking for. Since you said elevation, this may be more appropriate.

Re: How do I get areas with a certain elevation out of a raster file?

curtvprice — Wed, 02 Jul 2014 19:20:41 GMT

The Slice tool is more appropriate for continuous rasters.

Slice followed by Feature To Polygon would probably do what you want.

Re: How do I get areas with a certain elevation out of a raster file?

andreabarrueto1 — Thu, 03 Jul 2014 07:58:52 GMT

The Slice tool is more appropriate for continuous rasters.

Slice followed by Feature To Polygon would probably do what you want.

Thank you for the slice recommendation. I did not know that tool. I tried it out on a classification on slope (using 9 classes, 0-10degree, 10-20degree etc) and it is perfect. However, for destinct classes in altitudes, the reclassify is more appropriate. The con tool I always struggle a bit, as most of the calculations are in my understanding easier done with the raster calculator 🙂

*Thank you*

a.