Point order when exporting

Feel free to ask any question here
Post Reply
a.patience
Posts: 9
Joined: Wed May 02, 2018 1:32 am

Point order when exporting

Post by a.patience »

When exporting data from CC in *.las format, the point order is lost.

For example, I load a file that is ordered by appearance (from an MLS system). When I export the file to a new *.las, having performed *any* changes to it, the file points appear to have been written in random order. I assume it is written by octree depth or some other indexing structure.

My question is, is there a way to retain the order of points in the file upon export?
daniel
Site Admin
Posts: 7709
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
Contact:

Re: Point order when exporting

Post by daniel »

Nope, there should be no difference... Apart if PDAL (the library responsible of saving LAS files in the 2.10 verdion) do this, but I doubt it a lot.
Daniel, CloudCompare admin
a.patience
Posts: 9
Joined: Wed May 02, 2018 1:32 am

Re: Point order when exporting

Post by a.patience »

daniel wrote:Nope, there should be no difference... Apart if PDAL (the library responsible of saving LAS files in the 2.10 verdion) do this, but I doubt it a lot.
Just tested in 2.9 beta and can confirm, my point cloud order is lost of export.

I am loading a *.las (internal las format 1), decimating it 1:2 with the "random" decimation method, then saving to a new file. The new files point order appears to be entirely random.

In some software I'm working on, I rely on point order for some computations, which is how I stumbled upon this.
daniel
Site Admin
Posts: 7709
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
Contact:

Re: Point order when exporting

Post by daniel »

Oh I thought you didn't perform any "change': the 'random' subsampling tool will change the order (and il will do it 'randomly' as it randomly picks the points until it has enough of them...). By the way all the subsampling options will change the order (even if the other algorithms are using the octree order instead of a random one).
Daniel, CloudCompare admin
a.patience
Posts: 9
Joined: Wed May 02, 2018 1:32 am

Re: Point order when exporting

Post by a.patience »

daniel wrote:Oh I thought you didn't perform any "change': the 'random' subsampling tool will change the order (and il will do it 'randomly' as it randomly picks the points until it has enough of them...). By the way all the subsampling options will change the order (even if the other algorithms are using the octree order instead of a random one).
My apologies, originally I thought it was reordering them even without editing the data.

Is there a way to reorder the points by a scalar value in CC?

I've written my own sorting algorithm but would like to not have to jump between apps.
daniel
Site Admin
Posts: 7709
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
Contact:

Re: Point order when exporting

Post by daniel »

Nope, there's no such function...
Daniel, CloudCompare admin
a.patience
Posts: 9
Joined: Wed May 02, 2018 1:32 am

Re: Point order when exporting

Post by a.patience »

daniel wrote:Nope, there's no such function...
No problems. Any chance of seeing point ordering functionality in the future?
daniel
Site Admin
Posts: 7709
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
Contact:

Re: Point order when exporting

Post by daniel »

Hum, as you are the only user that ever requested this functionality, I doubt it will be implemented by the community soon...
Daniel, CloudCompare admin
Post Reply