Questions about the transformation matrices in PTX

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JeffMich
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Questions about the transformation matrices in PTX

Post by JeffMich » Mon Apr 12, 2010 3:57 pm

Hi friends,

We just bought a Leica Scan Station 2, starting doing some fun projects. Because we need to know both the native coordinates and those after registration to manipulate the point clouds, we have to know the exact meaning of the two transformation matrices for each scan. Can someone kindly explain them in detail? such as how to apply them (I notice one is 3x3, and the other is 4x4) to the xyz coordinates, pre-multiply or post-multiply? etc... Many thanks!

Jeff

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stevenramsey
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Re: Questions about the transformation matrices in PTX

Post by stevenramsey » Mon Apr 12, 2010 4:07 pm

This is what I have for the PTX format which might help.

I'm really interested to understand why you need to know the details, are you writing your own software to manipulate the clouds.



40 Scan 40degree x 40degree (point cloud #2)
40
4.151261 1.736411 -8.110131 # xyz offset begin transformation information (point cloud #2)
-0.434947 -0.017233 -0.900291 # transformation matrix
-0.240839 0.965618 0.097871
0.867650 0.259394 -0.424143
-0.434947 -0.017233 -0.900291 0 # angular transformation matrix
-0.240839 0.965618 0.097871 0
0.867650 0.259394 -0.424143 0
4.151261 1.736411 -8.110131 1
4.146983 12.074142 1.134998 0.488502 76 74 91 begin coordinate list (point cloud #2)
4.147541 12.075727 1.136227 0.486915 76 74 91 format: X Y Z intensity R G B
4.147919 12.076833 1.137371 0.486976 76 74 91 intensity range: 0 - 1
4.148849 12.079544 1.138655 0.485328 76 74 91
4.146931 12.073991 1.139137 0.486076 76 74 91
4.148440 12.078399 1.140532 0.488441 79 76 93
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JeffMich
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Re: Questions about the transformation matrices in PTX

Post by JeffMich » Wed Apr 14, 2010 6:39 pm

Hi Steven,

Many thanks for your reply. Yes, we are developing some visualization software based on the environmental scans, which is now still at a research stage. Hopefully, our work may eventually contribute to this community from the computer science side. :)

There is still one thing I am not very clear about. Could you please explain the angular transformation matrix in a little more detail? This concept seems new to me. Also, the 3x3 transformation matrix should be applied to the xyz by pre-multiplication or post-multiplication?

As an "insider" at Leica, you must have much more information sources than us users, don't you? ;) Your help is rather appreciated!

Jeff

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Re: Questions about the transformation matrices in PTX

Post by Romuald » Fri Jun 11, 2010 6:22 pm

Hello,

Those informations are interesting.
But how did you get the PTX files with this information.
In Cyclone I got a project register. I export stations from the scanworld register in PTX file format. And inside, the transformation value are field only by 0. There is no value.
How I should do to get PTX including transformation value ?

Thanks

Romuald

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masimo
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Re: Questions about the transformation matrices in PTX

Post by masimo » Thu Apr 07, 2011 3:22 am

Hello!
Can anyone explain me? How should I change PTX header if I want to transform it and I have transformation information?

For example
Original PTX file header:
3373
1438
0 0 0
1 0 0
0 1 0
0 0 1
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1


Transformation information:
ROT_X: +0.391220
ROT_Y: +0.769151
ROT_Z: +103.582959
SHIFT_X: -3.549417
SHIFT_Y: -6.585291
SHIFT_Z: -0.242803


Thanks in advance,
Maxim

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