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I'm using Quick Terrain Modeler (QTM) 64-bit v8.0.3.4 - I have a set of LiDAR data that has some points that I want to delete, but due to their location it is hard (if not impossible) to delete them by merely using the Select Polygon (Screen) tool without deleting other desired points.

So, the way around it is to use the Start Mensuration tool and then select Profile Analysis Tool in order to cut away specific points. However, this can be a bit tedious and not always a one-shot process. I found that while in the Profile Analysis you can select Mask to Area in 3D, in which (temporarily) only the selected area of interest is shown. Once in this view, I choose the Select Polygon (Screen) tool again and select the bad points and then cut them. However, this cut still deletes the points behind the bad ones, even though I've temporarily made everything else disappear.

So my question is this:

Is there a way use the Select Polygon (Screen) and Cut tools in conjunction with the 'Mask to Area in 3D' selection, without cutting/deleting points that are not visible/in the area of interest?

Here's an example of what I'm talking about. The first picture is with Mask to Area in 3D turned on and I'm cutting the faulty points. The second picture is showing the unintended cut, after turning off Mask to Area in 3D.

cut 1

cut 2

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I e-mailed the support team at Applied Imagery (maker of QTM) and received this response as an answer to my question:

Some of our filtering/cutting/cropping is simply a display trick of hiding the points, while others actually removes them from memory. The MASK TO AREA IN 3D function is a display trick, that is why the points are being acted upon even when you can’t see them.

I would recommend you use the ANALYSIS > FILTERING > SET CLIPPING PLANES and adjust the planes so you can see a narrow band of your area of interest. You can then use the SELECT POLYGON SCREEN tool to select and delete the points. The background points should not be cropped out when using the clipping planes.

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  • I tried the suggestion, it doesn't help in the slightest unfortunately. – JumpInTheFire Jun 11 '15 at 21:23

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