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I am using ArcGIS 10.3.1 for Desktop. I have a raw .las file that I have brought into an ArcGIS .lasd file format.

The raw data has several anomalous points; i.e. the maximum elevation for any point should only be 100 meters but there are perhaps 30 points with an elevation above 1000 meters.

I would like to delete these anomalous points.

The points are unclassified except for "ground". All others, including the anomalous ones, are "unclassified".

There doesn't seem to be a way to select these, or filter them out and then write a new .las / .lasd file that has eliminated them.

Andre Silva
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Lynn
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  • why not use a LAS layer? – radouxju Sep 12 '15 at 19:46
  • Thanks but I am going to be doing further work with this file - trying to get tree canopy - and so I really need to get rid of these points all together. – Lynn Sep 12 '15 at 23:38
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    I have found LASTools, http://rapidlasso.com/ which includes a custom toolbox....the lasheight tool has enabled me to delete the points. – Lynn Sep 16 '15 at 01:09
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    great, I suggest that you add this as an answer to your own question (with a few additionnal details on how to use the lasheight tool etc) and you'll get my upvote. – radouxju Sep 16 '15 at 06:41

2 Answers2

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As you cited, lasheight from LAStools can do the trick (used from ArcGIS). It says:

Another alternative is to use the computed height to eliminate points with a particular ground height above or below a threshold ... .

Example:

lasheight -i *.las -odix _no_outlier -olas -drop_above 100.0

The above example will make a batch call (i.e., with multiple input files), will keep points with height up to 100 units (e.g. 100 meters) above the ground, and will append the suffix name 'no_outlier' in all the output las files.

So, you would need to identify where is the gap between the outliers from the other points, and set the correct threshold value for -drop_above.

Another option is the native tool from ArcGIS Desktop Locate Outliers:

Identifies anomalous elevation measurements from ... LAS datasets that exceed a defined range of elevation values ... .

You would set the tool with the Apply Hard Limit methot and the Absolute Z Maximum parameter equal to 100 meters.

Andre Silva
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Might be worth a thought: If the undesired points are significantly(or just noticeably) higher than the rest of the data, you can convert to .txt, open in spreadsheet editor, sort z-value column by descending, manually remove all points higher than desired data height, and then convert back to .las

Riley Breen
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