import point list

[fussili]

Hello,

first: Thanks for CloudCompare!

But of course - I have a problem:

I have some unregistrated point clouds from the same objekt and I want to align them with as little efford as possible. But they are very complex and it´s not possible to do this visuably by 4 point-picking (at least without getting mad).
But in the software of the scanner I have for every cloud a list with some points, which should be used as tiepoints.
I can export both pointclouds and tiepoint lists and import them into CloudCompare, but I´m not able to get the information in that the tiepoints have names and are elements of the pointclouds.
To sum it up, is there a possibility to merge the tiepoints with the refered pointcloud without losing the Information: "this exact point is tiepoint 1"? In my next step I would set just the tiepoints visible and align them with pointpicking ( and in my dreams the clouds are fitted magically ;) )
Or is there another better way to solve my problem?

I`m thankful for every hint!

PS: The actual software for my pointcloud is a bit old and I haven´t found such a useful tool like "please merge my tiepoints" or anything else automated. I have only the option to do it manually and this doesn´t work very well.

[daniel]

Hum, the only trick I see right now is that you can import both sets of tiepoints, then use the corresponding clouds as is (i.e. without merging them to the "big" clouds) in the Point pair-based picking tool to align them. On completion you'll get the transformation matrix in the Console.

You can copy this transformation matrix (click it and press CTRL+C), then open the big cloud corresponding to the aligned tiepoints, and then apply the transformation matrix to the big cloud (with 'Edit > Apply transformation' - press CTRL+V or use the 'clipboard' button).


To help you register the tiepoints alone, you can try to display their index as a scalar field? (and of course increase their size).

[fussili]

Hi Daniel,

thank you for your answer!
I tried the way you explained, but perhaps I missed something, because it worked not as expected:
what do you mean by "... then use the corresponding clouds as is"? Do I have to click any button with "is"? (I haven´t found this yet)

The aligning of the tiepoints were fine, and also applying the matrixtransformation to the cloud. But then the tiepoints aren´t at the same place like the cloud (they are about ten meters left from my cloud and this is obviuosly false) and so the clouds aren´t fitting neither. Do I need perhaps to export further Informations except x,y,z-Koordinates for getting the right information?

Or can anybody imagine another reason?

[daniel]

"as is" is an english expression ;) (it means "as they are", "without modifying them", etc.)

So I only meant to use them directly...

And for the resulting shift, this is a bit surprising. When you import at first both the big cloud and the tiepoints do they fall in the same place? Do you need to setup a 'global shift' by the way? (i.e. the cloud has big coordinates).

You can also check that the matrix you see in the Console is the same as the 'Transformation history' matrix in the align (tiepoints) cloud properties (assuming you only aligned them once). Otherwise you should use the 'Transformation history' matrix instead.

[fussili]

:)))) aaah, everything´s a bit more confusing with a foreign language ^^

I found the error - I was importing from different coordinate systems. I just had to set the coordinates for the tiepoints in the "project coordinate system" and not in their own and export them afterwards. Then imported CloudCompare everything was fine and worked like expected.

Thanks!