Align and transform

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nsicart
Posts: 3
Joined: Mon Feb 07, 2022 7:31 pm

Align and transform

Post by nsicart »

Hello,

I have a pointcloud I got from a drone survey. It is georeferenced so the relative distances are correct.

I have another point cloud I got from and Iphone Lidar. It is a point cloud of a specific zone of the big point cloud.

I want both point clouds to be aligned and I want the lidar one, also to be transformed and adapted to the geroreferenced one.

Is it possible?

I use the Registration -> Align tool, and it seems it works.... BUT... it doesn't transform the point cloud itself it only tries to put it aligned with the other...

I send A photo so you can see what I mean

Thanks
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daniel
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Re: Align and transform

Post by daniel »

Hum not sure to understand... Have you clicked on the green check once you are happy with the alignment? Because this tool is exactly meant to be used for that (transforming the coordinates of the 'aligned' point cloud, in the 'reference' cloud coordinate system).

And I see that you have large coordinates here. You should apply the Global Shift when loading your georeferenced drone cloud. Otherwise you'll lose accuracy. The Global coordinates will be restored (even for the aligned cloud) at export time.
Daniel, CloudCompare admin
nsicart
Posts: 3
Joined: Mon Feb 07, 2022 7:31 pm

Re: Align and transform

Post by nsicart »

I use the align tool until the end. I've clicked on the green check at the end and it transforms the coordinates of the aligned point cloud BUT, it doesn't transform or adapt the point cloud to match the reference points. It doesn't change its relative distances.

I'm used to use QGIS for GIS data management, and I work with a tool called georeference which from a raster (or a scanned old paper map) you can assign some reference geolocated points and then the aligned raster is transformed, adapted, stretched or shrunk to match the referenced points.

I'm looking for something like that so I can have the correct relative distances like I have in the main point cloud but with the hight resolution point cloud of iphone's lidar for some parts.

Thanks
nsicart
Posts: 3
Joined: Mon Feb 07, 2022 7:31 pm

Re: Align and transform

Post by nsicart »

These are the transformation types you can use in QGIS if you want to georeference a raster
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daniel
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Re: Align and transform

Post by daniel »

The best you can achieve is indeed to adapt the scale (with the dedicated checkbox). But CC won't do anything more 'funky' than that ;)
Daniel, CloudCompare admin
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