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Point order when exporting
Posted: Sun May 06, 2018 10:59 pm
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?
Re: Point order when exporting
Posted: Mon May 07, 2018 5:35 am
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.
Re: Point order when exporting
Posted: Mon May 07, 2018 6:20 am
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.
Re: Point order when exporting
Posted: Mon May 07, 2018 6:47 am
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).
Re: Point order when exporting
Posted: Tue May 08, 2018 10:10 pm
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.
Re: Point order when exporting
Posted: Wed May 09, 2018 4:11 pm
by daniel
Nope, there's no such function...
Re: Point order when exporting
Posted: Thu May 10, 2018 10:33 pm
by a.patience
daniel wrote:Nope, there's no such function...
No problems. Any chance of seeing point ordering functionality in the future?
Re: Point order when exporting
Posted: Fri May 11, 2018 2:11 pm
by daniel
Hum, as you are the only user that ever requested this functionality, I doubt it will be implemented by the community soon...