Rotating a point cloud with lasgrid

[adri...@nevada.unr.edu]

I wanted to rotate a point cloud with lasgrid to look at it from the side and I can see in the README.txt an argument called "rotate_xy". It requires 3 arguments: angle, rot_center_x and rot_center_y. I am a bit confused how to use the last 2 arguments (rot_center_x, rot_center_y). I was guessing it could be the center coordinates of the point cloud, but it seems to always generate a point cloud at bird's eye view. Maybe my angle parameter is incorrect? I kind of been throwing random numbers in to see if anything makes a difference, but no luck.

[Martin Isenburg]

Hello,

when using the on-the-fly transform '-rotate_xy' with lasgrid then you rotate the point cloud on read and produce a raster as output. To go from point cloud to rotated point cloud use las2las with the  on-the-fly transform '-rotate_xy'.

Maybe send us a lasinfo report of the LAS file you want to rotate and the exact command lines that you have tried.

http://rapidlasso.com/lasinfo

Regards,

Martin

On Sat, Apr 24, 2021 at 3:08 AM adri...@nevada.unr.edu <adri...@nevada.unr.edu> wrote:

I wanted to rotate a point cloud with lasgrid to look at it from the side and I can see in the README.txt an argument called "rotate_xy". It requires 3 arguments: angle, rot_center_x and rot_center_y. I am a bit confused how to use the last 2 arguments (rot_center_x, rot_center_y). I was guessing it could be the center coordinates of the point cloud, but it seems to always generate a point cloud at bird's eye view. Maybe my angle parameter is incorrect? I kind of been throwing random numbers in to see if anything makes a difference, but no luck.

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[adri...@nevada.unr.edu]

I attached a txt file generated from lasinfo. The command is in bold below:

$ las2las -cpu64 -i "R:\SCRATCH\adrianom\riscan\check\ds\TLS_0001_20180606_01_downsampled.las" -odir "R:\SCRATCH\adrianom\riscan\check" -rotate_xy 30 -86225 2126463

where (-86225, 2126463) is roughly the center coordinates of the point cloud. I was told by a colleague of mine to use the center coordinates as parameters, but I am unsure why. I see in the readme that "-rotate_xy" requires (angle + origin), so I'm assuming that my x and y parameters are wrong.

[Martin Isenburg]

Hello,

rotating TLS point clouds by large angles is really not the usual use case of LAStools. I think there is much better support for this operation in CloudCompare.

Regards,

Martin

To view this discussion on the web visit https://groups.google.com/d/msgid/lastools/51ce6d38-687e-4bfc-91cb-27aeb4027c28n%40googlegroups.com.