Camera Calibration Wide Angle Lens
Posted: 08 August 2018 10:12 AM   [ Ignore ]  
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Joined  2018-05-24

Hi, I am having a problem with the Calibration Tag because I don’t know what the lens profile is. The camera seems to be using a wide angle lens, but when the tag is on you can’t change the Focal Length. So the solution would be to get the Lines and pin all set up, make a copy of the camera and delete the Calibration tag and move the camera manually after?

I would post a project file but I get a MIME type eroor, which I have no what that means. It’s just .zip file.

Thanks for your help
Mike

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Posted: 08 August 2018 11:02 AM   [ Ignore ]   [ # 1 ]  
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Hi Mike,

My initial result was a 16mm/FF lens, however, the vertical lines are all pretty much arguing against the point of view and the lens: This is not an image that was provided as raw image, except a shift (tilt) lens was used. I don’t think that it was corrected with software, as the vertical lines are not really vertical. Perhaps it was done in Ps, which would reduce the quality by half, which is what no pro would do IMHO, but then it was not a good job either: So I exclude that fo now. Something is wrong with that image compared to raw, that I can tell with certainty, and if you want to work with this content, you need to get into contact with the photographer. Since I’m not aware of a pro 16mm shit (tilt) lens, my best guess would be the 17mm TS/E. The image meta data is erased so I can’t say more. Since I really don’t know what was done to the image, the estimate of 16mm or 17 might come as close as possible at that time.

Any camera lens has more or less distortion, which means (simplified) how much natural straight lines become a curve. If you set the “Lines” for example on a slightly curved line, then the length and position of the line is changing the final result. If the image line would have been straight, based on a correct Lens Profile, the length and position of the “Line” could be changed (while matching the line) and the result wouldn’t change. Hence, why a lens-profile is crucial to take from the lens camera combination that was used. Each lens is different, even the same model line has variances.

Always (zero exception if quality is wanted) use the full image, not cropped nor corrected, best ask as well for the raw-version.
https://help.maxon.net/us/#TOOLLENSDISTORTION

Here is my take, given all the points from above, I switched the Settings> Calculate the PP for 3VPs to off, as the obvious change in the image would prevent a solution other wise. You have to link you image back.
Scene file
https://www.amazon.com/clouddrive/share/Mk0F0HmD0grqBuzIUc23lxTLDFId2D8Lgdxt2FPXySt

Screen shot (let me know if that is more a private image…
https://www.amazon.com/clouddrive/share/Lw28hioxQlaEVWb09VbkXPV9z4mKE8ph7rSEb3oflec

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
https://www.youtube.com/user/DrSassiLA/playlists

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Posted: 08 August 2018 11:23 AM   [ Ignore ]   [ # 2 ]  
Total Posts:  4
Joined  2018-05-24

Awesome, thank you. I figured it was something with the file/image but I still have to work on it regardless so your explanation is helpful.

Also, this might be a silly question but how do you figure out what the X and Z spaces are in a picture like that?

Thanks for your time again
Mike

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Posted: 08 August 2018 12:43 PM   [ Ignore ]   [ # 3 ]  
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You’re very welcome, Mike.

You say you have to work with the image – regardless. Not my suggestion, and not my intention by sending the file to you, just to be on the same side with that.
I know that I’m always too picky with this stuff, but trouble way back in time with clients lead me to share this, there are limitations of what can be “healed” in C4D.

Please keep in mind that any changes on the perspective of the image, if not recognized, will lead to problems. Even the file that I have send you works to a certain or larger degree, I would write a memo to the source/provider that this is not ideal and might harm the quality. To make that point more clear, there is an “idea” of transforming an image in Photoshop and have it straightened; This might ruin its usability completely, not only its quality. Even the Film Offset X or Y can’t help that in some cases.

As mentioned, if you don’t work from the original output of the camera, with all information needed, some alterations can’t be simulated in Cinema 4D.

To your question about the X, Y or Z direction. Well, that is completely up to you. The only rule that exist, if the selected edges of objects are not 90º to each other, you get wrong results. The designation of X, Y or Z is an Artist decision. Note that not everything is parallel or in 90º, the gutter of every house is by design not horizontal, for example. Which is a common mistake, hence why I mention it.

My best wishes for your project

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
https://www.youtube.com/user/DrSassiLA/playlists

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