Importing georeferenced clouds

[keellaw]

Hello,

I am attempting to compare two georeferenced landscapes and am having trouble getting them to align. Both models are georeferenced with WGS84 coordinates and are built from photos of the same area, but at different years. I import both as LAZ files and they import successfully, but one appears about 1/4 the size of the other and perpendicular. I am skeptical the 3-point alignment will work for this scenario, since it would be very difficult to choose exact similar points at this scale. Is this an issue that needs to be fixed in the making of the models, or can it be resolved in Cloud Compare?

Thanks,
Keely

[daniel]

They are both with WGS84 coordinates but in the end they are in totally different coordinate systems? That's weird indeed.

Can you maybe share the two files with me? (admin [at] cloudcompare.org).

When CC imports the file and suggests you to apply a 'Global shift', does it suggest you to use the exact shift and scale values? (especially the scale one - hopefully it should be 1 in both cases).

[WargodHernandez]

Another possibility, is the units of the original scans, is one in M another in MM or MM and inch?
Cloud compare in general is unit-less so if the sources are different units they will look scaled to one another

[keellaw]

Both of the photo sets were from the same source (USGS EOS) and they give the measurements in mm, however, I haven't been able to find any guarantee that those are actually the units tied into the metadate. That could definitely be worth looking into!

[daniel]

So I go the data, and it seems one of the cloud is really weird (the vertical is not +Z, the LAS offset is (1000, 1000, -1000) which is also super weird along Z, etc.). While the projection info are exactly the same as the other cloud...

And the units are in meters by the way (according to the projection info).