Reduce points in Point feature from a 30 meter DEM raster

[ChrisMartin9]

I have created a point feature from a 30 meter DEM raster and I would like to reduce the number of points (decimate) - the number of points are too large to manage. Is there a toolbox for this or can this be done with the select attribute tool. Thanks.

[IanMurray · Accepted solution]

Another option is to simply resample the raster down to an even lower resolution before converting to points.

[ChrisMartin9]

That's perfect. How do I resample the raster?

Sent from my iPhone

[IanMurray]

See this tool help.

ArcGIS Help 10.1

[ChrisMartin9]

Ian,

It looks like this will work!

Thanks.

[XanderBakker]

What interests me most, is why you converted the raster to points? What is your goal with that? Do you want to mimic a point cloud or is there a specific analysis you plan to do on the points?

[ChrisMartin9]

Xander,

I have to create a simple xyz flat file that I can grid in another software program and by converting the raster DEM into a point file I already have the z portion - I just needed to add the xy coords and export out as a csv which I can bring into the program. The problem was the software program was choking on the amount of points generated from a 30m DEM.

[DanPatterson_Retired]

I am sure you are aware of the potential effects of resampling to a lower resolution and these should be addressed or considered before using the results as inputs to other processes.  For the sake of completeness, the discussions given in the help are useful....especially for those that just accept the defaults as a matter of course.

Resample—Help | ArcGIS for Desktop

Aggregate—Help | ArcGIS for Desktop

[XanderBakker]

Hi Chris, thanks for the additional information. It makes sense that a software package chokes on a CSV file if it contains a large amount of records (which it will probably have). Resample is a simple way of reducing the amount of data but will result in loss of quality as Dan mentions. If there is no other exchange format that ArcGIS can write to and the other software can read from, and the extent has been reduced to a maximum, here is not much left to do.

[curtvprice]

If you have 3D analyst you can convert to a TIN with a tolerance, the TIN can then be exported to points, which then can be re-gridded by your external program. This approach would allow you to preserve more detail than simply using Resample (or, better, Aggregate) to create a coarser regularly-spaced raster.

[ChrisMartin9]

Xander,

I do have 3D analyst but I have never done this. Do you have more information on how to convert the raster to a TIN and then export to points?

Thanks.