Question: About coordinates of point clouds

#1

I am very interested in VRSketch.
I found in the documentation that it can read the position (XYZ) and color of point cloud data.
VRSketch cannot move the point cloud data, etc., but will it be placed in the coordinate values that the point cloud data has?
I saw an article that said VRSketch cannot move point clouds, but can move and rotate SketchUp models to composite them.
However, I am assuming that if VRSketch is placed at the coordinates of the point cloud, then the model and point cloud can be combined if the SketchUp model is also placed and saved where it can be combined with the point cloud.
I don’t have a Potree environment, so if you know of one, please let me know.
Thank you.

#2

Welcome to VRSketch!

Yes, that’s right. Think of the point cloud as being attached to your Sketchup model’s coordinates. If you move/rotate/scale the view of the model in VRSketch, then the point cloud moves/rotates/scales along with it. The point cloud is fixed relative to the model.

You can edit the model itself to move the faces and groups it contains, so you can move it until it matches the fixed point cloud.

About Potree, see https://vrsketch.eu/docs-pointcloud.html and the link to the right version of Potree in the section “Convertion from LAS/LAZ to Potree”.

A bientôt,
Armin Rigo

#3

Thanks for the answer, arigo.
I see that the point cloud is placed at the coordinates it holds.
Excellent!
A point cloud taken in survey coordinates is placed at coordinates very far from the origin (0,0,0).
ScanEssentials places it at Y,X,Z, so if you place the model at the same position as the point cloud in SketchUp and draw the point cloud in VRSketch, the model and point cloud will be merged by coordinate values.

I will ask my contractor to build a Potree for me.
If you keep the coordinate values of the point cloud data, it would be more convenient if you could search for the coordinate values within VRSketch and implement a markup or color change.
I will report back after testing.
Cheers.

#4

VRSketch may not give you the best experience if the coordinates are very far from the origin. Maybe you can have the point cloud re-centered when converting it to Potree.

The point cloud will appear extremely far from you in VR, and finding where it is might be difficult. There are also precision issues: the numbers are internally converted to 32-bit precision when being sent to the GPU. Points 30km away from the origin get only a few millimeters of precision; points 3000km away get only ~25 centimeter. At such large distances there are also other precision issues in VRSketch that will get in your way, like when using the teleport tool.