Dimension position parameters TRx Try TRz

[Kai M]

Hello together,

for a project I create a pto file by script.A camera is moved over the object in defined distances and pictures are taken. Therefore I use the Mosaic Mode.

I still lack the understanding for the dimension of the position parameter TRX TRY TRZ. In which dimension are the parameters specified? I would be happy if someone could explain this to me.

Best regards from Germany

Kai

[dgjohnston]

Kai, is this a 3D object?  I believe Mosaic Mode is meant for 2D images like a picture or mural.  A 3D object will introduce parallax errors that will make it hard to stitch unless you are really careful in placing control points and then masking out any overlaps.

Kind regards from Canada.

Don

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[Kai M]

It is just a 2D Object. Stitching works very well if i only optimze TRx and TRy. But i try to understand in which dimension these Parameters. On a camera movement of round about 30cm i get a TRx of 0.521 . I try to understand this number.

[dgjohnston]

Perhaps this link might help … I had to read it very carefully a few times … even though English is my first language.

The picture in the link is from the perspective of someone looking down on you standing at the origin 0,0,0.

From your camera's point of view taking the picture looking at the “Projection Plane”: X is the camera moving left-right (-ve to +ve), Y is the camera moving down-up (-ve to +ve), and Z is in-out (-ve to +ve … “in” being closer to the projection plane)

If you’re in a plane taking a picture straight down just think from you point of view as laying down pointing the camera straight down … so Z is “in” to the ground (it’s always relative to what your camera is looking at).

I believe from this then that TRx of 0.521 being 30cm is relative to the “Projection Plane” at Z=-1 (and the panosphere radius r=1); r must be at about twice (1/0.521=1.919) 30cm or 57.6cm.

https://wiki.panotools.org/Stitching_a_photo-mosaic

and

On Sep 6, 2018, at 10:47 AM, Kai M <k...@mayfarth.eu> wrote:

It is just a 2D Object. Stitching works very well if i only optimze TRx and TRy. But i try to understand in which dimension these Parameters. On a camera movement of round about 30cm i get a TRx of 0.521 . I try to understand this number.

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[Kai M]

Hello Doanld,

Thank you very much for your answer. Slowly I understand it.  But I have another question:

I move the camera with an accuracy of <1mm over the target. Now I want to try to skip the step of CP detection and calculate the positions of TRx TRy myself and create a pto file. Unfortunately I still have no idea how to calculate the TRx and TRy parametersthis. Maybe someone can help?

Greetings from Germany

Kai

[Don Johnston]

This is where I would have to switch into experiment mode. Maybe someone with more experience on this could help.

Was you camera at about 60 cm from the object as my calculation in the previous response showed? Did hugin have access to all the exif data in the image so it knew focal length etc.

Maybe calculate TRx by dividing your 30 cm by the distance from the object that you used when taking the picture, then do a stitch and see how it looks.

Don

[Kai M]

Hey Donald,

i tried everything to calculate. But i cant figure out the parameters. The Exif Data is readable. The Distance was 40cm from the object. Do you think its possible to calculate it in Pixels?

Best Regards

Kai

[dgjohnston]

Sorry, I’ve exhausted my knowledge on how hugin might be calculating and using these numbers; it doesn’t seem to match the theory written up in the links I put up.

Would any of the developers / support guys have any thoughts on this for Kai?

Don

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