Export points to WGS 84 in blocks unexpected behaviour

[swinersha]

I've been trying to export points from a model of a forest landscape with approx. 3 million points from version 1.2.4.2399 (which I believe is up to date at the time of writing). When I use local coordinates and split into 10 m x 10 m blocks, the routine works like a charm and I end up with 350 files. However, when I try to export to WGS 84 the routine says it's going to take weeks to run. I left it running for 12 hours and it had already generated nearly 1 million files.

I'm guessing that the block size is not being converted from meters to degrees before the routine commences. This would cause the size of the blocks output to be far smaller than that requested and require millions of files.

Would you be able to fix this please?

Let me know if you need any more info.

[Alexey Pasumansky]

Hello swinersha,

Thank you for reporting.

Please provide the following details about the project, so that we can reproduce the issue:
- approximate total area covered,
- number of points in the dense cloud,
- export settings used.
If possible, please also provide the console pane output related to the problematic export.

[swinersha]

Hi Alexey,

Thanks for getting back to me so fast. Here are the details as requested.

- 2km square
- 3 million points
- Settings: export to ASPRS LAS and see attached image.
- Console pane output:

2016-06-07 09:44:42 Saving point cloud...
2016-06-07 09:44:44 exporting 133000760 blocks (13205x10072)
2016-06-07 09:44:50 Finished processing in 6.414 sec (exit code 0)
2016-06-07 09:44:50 Error: Aborted by user

[Alexey Pasumansky]

Hello swinersha,

Thank you for providing additional details, and in which system is referenced the original chunk (projected or geographic)?

[swinersha]

The chunk is in WGS 84 EPSG::4326.

[swinersha]

Hi Alexey,

Have you had a chance to take a look at this? Please do let me know if you figure out what the problem is.

[Alexey Pasumansky]

Hello swinersha,

Up to now we haven't been able to reproduce the issue. Maybe you can give some additional hints how we can reproduce that? Doesn't it happen in any project referenced in WGS84 (obviously incorrect number of blocks), or only for the merged chunk like in your case?

On the screenshot is it the whole combined chunk or just a pert of it?

[swinersha]

Hi Alexey,

I think it may have just been the merged chunk. I have since deleted the merged chunk as I noticed that it had actually been aligned in a totally different plane (45 degrees from the ground). Perhaps that could have been the cause.

I have just tried to recreate the issue too and couldn't; the number of blocks created is identical in WGS 84 and local coords.

Tom

[Alexey Pasumansky]

Hello Tom,

Then the chunks could be incorrectly aligned before the merging operation.

You can display all the enabled chunks that are referenced (have [R] mark next to their label in the Workspace pane) at once using Show Aligned button located on the toolbar. So if you see that the chunks are not oriented properly, merging will give incorrect result.

[swinersha]

Yeah I have discovered that very handy function in the last couple of days.

Actually the chunks do look well aligned (see attached) but in a couple of the chunks some of the transects seem to have been only aligned in line but not between line. This seems really weird to as I think the GPS locations are correct so I would have thought the camera locations would at least be constrained to be in the correct plane but this doesn't seem to be the case. Is there a work around for this kind of problem? Manually aligning the images seems a very long winded approach, which is not at all easy for trees.

[swinersha]

I've also just looked at the result of the exported LAS files and when they are in local coordinates they look fine but when they are in WGS 84 they are really stretched out in one of the dimensions (see attached image local is the 2nd pane, WGS 84 is the third; I can dropbox the LAS files to you if that would be useful).