The below documentation is for the process of getting a clean pavement blocks, especially focusing on removing off-ground objects.

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Step 1. Segmentation

Use segmentation tool (Hotkey: T) to remove areas unwanted.

Other than the x-y axis, it’s as important to clean up the z axis points, even if they look like only empty space. (The reason are in the next steps.)

cleaned up point cloud

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Step 2. CSF Filter

CSF Filter is a plugin that can separate ground and off-ground point cloud.

It’s crucial to clean up z-axis point cloud first, so that this plugin wouldn't identify the incorrect ground. If it does, the whole street would be accounted as the off-ground point cloud. This function can be found in:

plugins—>CSF Filter

I found “Relief+Slop processing” to be the best in handling street pavement.

Result after filtering out off-ground objects. Further clean up can be done by segmentation again.

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Step 3. SF Filter

I already assigned the SF as the one that I used for pavement classification. It goes as follows:

For filtering out the paint, which is non-necessary in our research, I use Filter by value function to split the paint intensity range from the others. This function can be found in:

edit—>scalar fields—>filter by value

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