Trimble Business Center

All,

I got a point cloud in which I have classified into regions.  The Ground region still has some clumps of vegetation that I need to get removed before I start building a surface to run volumes on.  I select the top of the stockpile where I got this extra vegetation and I ran the sample by intensity command which worked real well.  However, I noticed that when I tried to add that sampled region to the high veg region the ground region still has the data that I though I extracted.  I am guessing I have to create a new region just for the the top of the stockpile and then run the intensity command and add that to a new region along with what was left over from the ground region to create my new cleaned ground point cloud.  Am I right?  If so it would be nice if you could possibly make a command where you could select by intensity in addition to the polygon so that you go do all this in one step.  Again if I am missing something here please let me know.  It seems that intensity region is still tied to whatever region, in this case the ground region and therefore copies if you will the data and not remove the data like polygon selection does.

Thanks, Ben

If you import a Classified Point Cloud or a Point Cloud that you then Classify - the Point Cloud is divided into Point Cloud Regions like Ground, Vegetation etc. If you e.g. Turn off all Regions except Ground and then use the Intensity Based Filtering to reduce e.g. Vegetation cover - it will by default create a New Point Cloud region for the data that you extract through this process. If you want to add that extracted data to a different region then use the Add To region command and select the Intensity Extracted data to that region. 

If the original Ground region has say 20 million points in the point cloud, when you do the Intensity Sample, the Point cloud region is effectively copied and then reduced by the sampling - the original region is not affected at all and will still have 20 million points in it after the sampling. The region that you create will have the reduced version of the Point Cloud Region - e.g.  5 million points or whatever. This is different to the Polygon Select and Create region which basically removes the data from the Original and places it into the new point cloud region.

So in your case - the Stockpile original with the vegetation included is your original - you use Intensity sampling on it to set a Low threshold value to pick the Vegetation and leave it out of the to be create point cloud region (Vegetation is typically always at the low end of the Intensity spectrum) - and you may leave the High End threshold at 255 - and then create the point cloud region - this will be the reduced ground with more of the vegetation removed. You can then start with that new region and take it a second step as necessary.

If there is only Vegetation at the top of the Stockpile - you should not need to use a polygon select as well - unless you do not want to affect other areas of the site (which may be all dirt for example) - in this case you would have to do Polygon Select fr the Top of Pile and Create a region (Pile Top) and then do Intensity Filter on the Pile Top region to create the Pile top (Cleaned) region and then add that back to the Ground on completion.

You can however do what you were asking in Intensity Based Filering

1. Define a region Name e.g. Ground (Cleaned).
2. Select the Ground Region
3. Define the Low and High Intensity Values. Now use Polygon Select to select the Top of Pile area and then hit the Store Button - this does exactly what you are asking for (combined Intensity and polygon area select.

The entire area above is my Ground - the poly selected area is my subset and Intensity sampling is defined. The stored output is this

Hope that this helps

Alan