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Author Topic: COPC .laz support for exporting point cloud  (Read 6549 times)

spader

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COPC .laz support for exporting point cloud
« on: April 13, 2022, 12:17:28 PM »
There is a push in the open source community for a new, backwards-compatible way of formatting tiled .laz files called COPC. The result is a single laz file that can be streamed/has LOD etc etc, which previously were restricted to potree/entwine exports which consists of thousands of files. At the same time it can be opened using all the standard laz reading methods, as it is "just a laz", in a manner similar to a cloud optimized geotiff is "just a tiff".

If Metashape would add support for exporting point clouds directly this would be really beneficial, since this would significantly reduce the overhead of using/showing others the billion-points large point clouds we routinely produce.

QGIS will support simple drag-and-drop copc laz in 3.26, and potree 2.0 will support copc as well. PDAL supports reading/writing copc as of 2.4.0. I am not sure about Cloudcompare, but I hope it will support copc.

A couple of helpful links:
https://copc.io
https://pdal.io/stages/writers.copc.html
https://www.lutraconsulting.co.uk/crowdfunding/elevation-pointcloud-enhancements-qgis/

andyroo

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Re: COPC .laz support for exporting point cloud
« Reply #1 on: January 28, 2023, 01:40:01 AM »
+1*10^6 for this feature request!!!

We are producing these as our standard .laz outputs now because they are SO easy folks to view compared to "normal" LAZ.

COPC is just a "flavor" of laz spec 1.4 organized as variable chunks in a clustered octree with with a couple of COPC-specific VLRs describing the data structure. LAStools is implementing COPC support, and it's super useful for rapid releases of products everyone can view.

(source is this emergency response data release).

Anyway, it gets me excited, and I hope I can export COPC natively from metashape soon instead of converting with PDAL, Untwine, or LAStools (soon).

JRM

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Re: COPC .laz support for exporting point cloud
« Reply #2 on: January 29, 2023, 07:32:03 PM »
spader > copc's support by cloudcompare isn't planned as the new 2.3 las/laz loader is rebased on laszip which currently lacks it

andyroo

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Re: COPC .laz support for exporting point cloud
« Reply #3 on: July 13, 2023, 11:38:52 PM »
Just wanted to re-raise this request. It's how I'm planning to publish several hundred aerial surveys, and it would be nice to be able to export as a COPC instead of writing out several TB of data then rewriting it as a COPC.


QGIS 3.32 now has much-expanded support for pointclouds, and COPC is what they're internally converted to if they don't already exist, from what I can tell.

@JRM I'm confused how laszip doesn't support copc - the spec makes it seem like it does:

"Data organization of COPC is modeled after the EPT data format, but COPC clusters the storage of the octree as variably-chunked LAZ data in a single file. This allows the data to be consumed sequentially by any reader than can handle variably-chunked LAZ 1.4 (LASzip, for example), or as a spatial subset for readers that interpret the COPC hierarchy. More information about the differences between EPT data and COPC can be found below."

JRM

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Re: COPC .laz support for exporting point cloud
« Reply #4 on: July 16, 2023, 12:17:16 PM »
andyroo > it means that cloudcompare and LASzip will open a COPC as a traditional *.laz file, there will no support of spatial access or levels of detail which are some of the main benefits of copc.

Alexey Pasumansky

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Re: COPC .laz support for exporting point cloud
« Reply #5 on: September 13, 2023, 04:04:22 PM »
Hello all,

We are planning to add support for export in this format in 2.1.0 pre-release.
Best regards,
Alexey Pasumansky,
Agisoft LLC

spader

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Re: COPC .laz support for exporting point cloud
« Reply #6 on: October 10, 2023, 09:44:35 AM »
Amazing. Just read the changelog. This will be a game changer for us. Keep up the good work!

Alexey Pasumansky

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Re: COPC .laz support for exporting point cloud
« Reply #7 on: October 10, 2023, 12:48:05 PM »
Hello spader,

Please share your feedback, if you have any issues with the newly supported format.
Best regards,
Alexey Pasumansky,
Agisoft LLC

andyroo

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Hi Agisoft folks!

VERY glad to see copc format supported. My feedback so far:

1) metashape copc export is the only way I can preserve confidence and normals and get my point clouds from metashape into .copc format (PDAL mangles/deletes user bytes) and lascopcindex64 throws coordinate system errors.

2) exporting COPC is about 40x slower than outputting normal laz files, which makes exporting large dense clouds.... problematic. (minutes turn into hours, and hours into days)

3) exhorting COPC with Metashape is still about  3-4x faster than converting .laz exported by metashape to copc with lascopcindex64, which also preserves normals/confidence but makes the data unusable with any other data because it destroys the CRS

4) exporting COPC with Metashape is about 60x slower than converting .laz files with PDAL/QGIS, which does a great job with RGB, XYZ, and classification AND shrinks filesize by 25% but I'm pretty sure the only reason the files are smaller is because it drops the userbytes due to deficiencies in PDAL support of data stored in user bytes.