5 Messages

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200 Points

Thu, Apr 18, 2019 10:32 AM

In progress

# Photoshop: Wrong horizontal FOV calculations

PS calculates horizontal field of view wrong, IT'S A BUG!!! See the proof. As you see PS says us that in this canvas size we've got a horizontal FOV like 75 and vertical 30. But it's a mistake. The real Horizontal FOV must be 67.6

The simple formula proves it

canvas width w = 5000 pixels

canvas height h = 2000 pixels

d = 3732,73 (distance to the center of projection)

Horizontal FOV 2 tan-1 ( w / 2d ) = 67.6

Vertical FOV 2 tan-1 ( h / 2d ) = 30

So if you try to save an image from PS and then create the same canvas size in Adobe Dimension CC or in any other proper application and use the saved image from PS as a background, then will put camera FOV 75 degrees you will certainly see that perspective of this cube will not match. But if you put in FOV the value like we've got in the formula above (67.6 degrees) the perspective will fully match because it's correct, it's simple trigonometry.

Photoshop can't determine the real perspective camera parametres frome the image. There is simply no any accurate tool. The vanishing point filter has problems with the FOV too. Just to try to create in PS some 3d layer and then use VP filter to reconstruct camera parametres just created)) You will see the wrong FOV. Basically that means that Adobe users haven't opportunity to add something to a real photo using any of ADOBE applications. How can it be in 2019? Comparing with the Sketchup I can determine an image perspective in minutes but if in Photoshop I must do it manually, using knowleges of geometry, of course if I want to get accurate results.

Look at this situation from such a point of view. Don't you think it's a weird thing? A user pays each year for Adobe applications and if he wants to add some object to a real photo he can't do it correctly with the help of Adobe products. For example he brought Adobe PS and Dimension. So he has a task to render some object in Dimension CC and put it into a real photo. What tool should he use to get an accurate results in perspective matching in order a rendered object match the real photo perspective? The answer is NO ONE tool here presents for now! He has to take a calculator and remember a school trigonometry formulas to exactly compute the perspective from any photo while other users could do the same via automatic tools of perspective matching in Sketchup, 3ds Max, etc. which works properly and could get accurate resuls in few minutes, they just need to show the application a group of parallel lines and that's all, the resulst mostly will be fully match.

#### Responses

5 Messages

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200 Points

2 years ago

This reply was created from a merged topic originally titled Photoshop: Says wrong horizontal FOV in 3D.

When you create a 3D layer Photoshop says (calculates) wrong horizontal field of view if the canvas is not a square. The similar problem is when you use the vanishing point filter. When you determine a group of parallel lines in the image and after try to back a 3D layer, the FOV calculations are always wrong, so the perspective of the image and created 3D layer doesn't match. Wherein no matter what type of the canvas the image is: square or rectangle.

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15.8K Messages

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295K Points

2 years ago

Thanks. I've asked engineering to investigate.

Sr. Product Manager, Adobe Digital Imaging

5 Messages

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200 Points

Thanks a lot! Hope you'll fix it soon and Photoshop get it's own accurate vanishing point filter which could calculate the perspective of image accurately after fixing. That will allow us to do our projects much more faster, qualitative and easily because then we will know the true camera parametres (FOV, X, Y, Z orientations, etc.) of a photo and could be able to put these parametres into Dimension CC camera in order to render 3d objects in the same perspective instead of taking a calculator and do it by ourselves what certainly takes a lot of time. Thanks!

1 Message

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82 Points

2 years ago

Hi,

I've also noticed the problem, here's an easier way to visualise it:

This problem, in conjunction with the FOV being limited to 180 degrees, makes it impossible to create a camera with a real FOV wider than 123 degrees. Unfortunately It makes it impossible for me to camera match some of my backplates.

ps: I would love to be able to access the film back settings, including being able to offset it.

a year ago

Hello! This perspective problem is frustrating to me as well. I have product images as OBJ files I need to incorporate into real-world photographs but I can not get the perspectives to match. I can draw perspective lines to find my horizon and vanishing points but no amount of manipulating the view properties will ever get them close to what I need. If it was just spheres in abstract backgrounds it would be close enough but inserting cube type shapes into a photo with other cube type shapes shows a very obvious error in perspective. I can assign a Perspective Filter and any every time I choose the view to be the Vanishing Point Grid it will rearrange the view (never the same twice - like it is random).

I can't just drop a photo into my 3D programs because I need to use photoshop to mask out areas of the 3D object so it becomes part of the scene - like the objects are integrated into the scene and not just plopped in front/on top.

Thoughts on this problem (or suggestions for other software that will do this) are appreciated.

Thank you!