Make point cloud from laser scan as "ground control" point.

Hi All,
I’m planning using point cloud from RC to calculate earthwork quantity. We have setup number of ground control points but the result is far from our expectation, the diffirent between RC result and actual can be half of metter.
We tried using laser scanner combine with pictute but result still not good.
I’m just wonder is there any way to make point clouds from scanner as the fixed point (kind of ground control point) and the points processing from picture will forced to follow it?

Hi phan manh quyet,

if everything is done properly it should work fine.

So I suspect there is some other issue here.

Did you use UAV images?

Is it possible some inaccurate GPS data interferes?

Hi Götz Echtenacher ,

Yes, we use image captured by drone. Actually, we have no problem to register, alight image& scan and create mesh. 

The issue is accuracy as mentioned in my 1st post, the result coordinate of point generated from RC is quite far with actual coordinate.

My workflow is:

  1. registered laser scan point (using Faro Scene)

  2. Import laserscan to RC, set “Absolute pose” to locked

  3. Import image, run alight (draft)

  4. Set GCP for image

  5. Run alight (normal)

As mentioned, the image and laser scan is alighted, mesh generated.

But the issue is the mesh (or point cloud) generated from RC is not accurate in term of coordinate.

 when we overlay the point cloud (original - register by FaroScene) and point cloud generated by RC, there are a lot of different.

Hi phan manh quye,

so your laser scan is not registered and geo-referenced?

Or why do you use GCPs in addition to a scan?

Without analyzing your workflow in detail, I still suspect that it might be related to GPS data, especially if the laser scans are not registered or geo-referenced separately. So my suggestion would be to try and process the images without using GPS info right from the start and see if that helps.