Camera sensor size does not honor scene scale factor #34481

New Issue

Tobias Oelgarte · 2013-03-01T00:35:42+01:00

Tobias Oelgarte commented

2013-03-01 00:35:42 +01:00

%%%I could write a lengthy description of the bug, but i already did at blenderartist.org. So i will give just include two links to two comments from myself, which should make clear whats going on:

http://blenderartists.org/forum/showthread.php?216113-Brecht-s-easter-egg-surprise-Modernizing-shading-and-rendering&p=2318109&viewfull=1#post2318109

http://blenderartists.org/forum/showthread.php?216113-Brecht-s-easter-egg-surprise-Modernizing-shading-and-rendering&p=2318528&viewfull=1#post2318528

In short: The camera sensor size has a default size of 32mm, which equals 0.032BE. But regardless of the scene scale it will always be treated as 0.032BE. So if i set the scene scale to 10, then i have a sensor with 320mm. -> Sensor size should be divided by scene scale, to still be 32mm.

%%%

%%%I could write a lengthy description of the bug, but i already did at blenderartist.org. So i will give just include two links to two comments from myself, which should make clear whats going on: http://blenderartists.org/forum/showthread.php?216113-Brecht-s-easter-egg-surprise-Modernizing-shading-and-rendering&p=2318109&viewfull=1#post2318109 http://blenderartists.org/forum/showthread.php?216113-Brecht-s-easter-egg-surprise-Modernizing-shading-and-rendering&p=2318528&viewfull=1#post2318528 In short: The camera sensor size has a default size of 32mm, which equals 0.032BE. But regardless of the scene scale it will always be treated as 0.032BE. So if i set the scene scale to 10, then i have a sensor with 320mm. -> Sensor size should be divided by scene scale, to still be 32mm. %%%

Tobias Oelgarte commented

2013-03-01 00:35:42 +01:00

Changed status to: 'Open'

Brecht Van Lommel commented

2013-03-01 15:18:04 +01:00

%%%The ratio of the sensor size and focal length defines the field of view, but sensor size does not and should not affect depth of field. The amount depth of field is proportional to the aperture radius, or alternatively to the ratio of the focal length over f/stop.

Anyway, the issue is that the tooltip that says that the focal length is in mm is wrong when using f/stop. I'm not sure what the solution would be here or if it needs to be solved. We could add units to focal length and sensor size but it would be annoying to have these values change as you change scene scale when you're not using f/stop.%%%

%%%The ratio of the sensor size and focal length defines the field of view, but sensor size does not and should not affect depth of field. The amount depth of field is proportional to the aperture radius, or alternatively to the ratio of the focal length over f/stop. Anyway, the issue is that the tooltip that says that the focal length is in mm is wrong when using f/stop. I'm not sure what the solution would be here or if it needs to be solved. We could add units to focal length and sensor size but it would be annoying to have these values change as you change scene scale when you're not using f/stop.%%%

Tobias Oelgarte commented

2013-03-01 15:33:30 +01:00

%%%The problem is that the camera (model) does not scale at all, while i can scale the entire geometry without any problem.

f-stop is a unit independent value. (will never be a problem of it's own)
The focal depth is already in units, which should stay that way.
The sensor size is also alright and does not need to be scaled. It is in mm and it stays in mm regardless of scale.

But the camera (the lens thing) should adopt to the scene scale value. Otherwise f-stop and sensor size will both be affected by scene scale and are not comparable to real world cameras, if the scene scale isn't 1 (1 unit = 1m).%%%

%%%The problem is that the camera (model) does not scale at all, while i can scale the entire geometry without any problem. * f-stop is a unit independent value. (will never be a problem of it's own) * The focal depth is already in units, which should stay that way. * The sensor size is also alright and does not need to be scaled. It is in mm and it stays in mm regardless of scale. But the camera (the lens thing) should adopt to the scene scale value. Otherwise f-stop and sensor size will both be affected by scene scale and are not comparable to real world cameras, if the scene scale isn't 1 (1 unit = 1m).%%%

Brecht Van Lommel commented

2013-03-01 16:31:15 +01:00

%%%The unit system is purely a user interface display thing, it should not affect how anything renders. That's a basic design thing to keep the scene and camera decoupled and make things like library linking work.

Further I can't tell if you disagree or if you're just stating things in different words.%%%

%%%The unit system is purely a user interface display thing, it should not affect how anything renders. That's a basic design thing to keep the scene and camera decoupled and make things like library linking work. Further I can't tell if you disagree or if you're just stating things in different words.%%%

Tobias Oelgarte commented

2013-03-01 17:29:32 +01:00

%%%Lets say i have two scenes which in metric dimensions are the same, but one of it has a scene scale of 10 (in internal units [BU] it is ten times smaller). If i have now a camera in this scene, then it is rendered differently, even if the metric focus distance and the f-stop is equal (both focus on same part and have same metric position).

The problem is that in the first scene (scene scale=1) you have normal camera. But in the second scene (scene scale=10) it is rendered as if the camera (lens and stuff) itself is ten times bigger (You traded a mobile phone camera for a telescope) . Thats also why it renders as if the camera would focus on a much closer distance, which is logical if the camera is that big, but shouldn't be that big.%%%

%%%Lets say i have two scenes which in metric dimensions are the same, but one of it has a scene scale of 10 (in internal units [BU] it is ten times smaller). If i have now a camera in this scene, then it is rendered differently, even if the metric focus distance and the f-stop is equal (both focus on same part and have same metric position). The problem is that in the first scene (scene scale=1) you have normal camera. But in the second scene (scene scale=10) it is rendered as if the camera (lens and stuff) itself is ten times bigger (You traded a mobile phone camera for a telescope) . Thats also why it renders as if the camera would focus on a much closer distance, which is logical if the camera is that big, but shouldn't be that big.%%%

Sebastian Röthlisberger commented

2013-03-06 19:52:24 +01:00

%%%I'd like to note that currently, if it scales the Aperture from 1mm to 1cm by scene scale 10, the feedback the user get is wrong, or could be understand wrong. Since the Focal Length and Sensor Size still let you assume it is a 35mm Lens and a 32mm Sensor, but the aperture now shows 1cm.

How about a Checkbox in the Camera to let it either not scaled (as it is now) or to let it scale everything?

I don't think the camera should generally adopt to the scene scale. If it would i could set scene scale from 1 to 10 and get completely different results if i don't match metrical scale by scaling the Object.

@Niabot. Ich hoffe du siehst diesen Punkt. Wenn ich zum Beispiel eine 3d Modell mit Kamera von irgendwo in Blender lade und alles ist viel zu gross, kann ich mit dem Scale alles verkleinern, ohne veränderung der Kamera, bzw DOF.
Ich wünsche dir (read You) einen schönen Abend. Gruss bashi
%%%

%%%I'd like to note that currently, if it scales the Aperture from 1mm to 1cm by scene scale 10, the feedback the user get is wrong, or could be understand wrong. Since the Focal Length and Sensor Size still let you assume it is a 35mm Lens and a 32mm Sensor, but the aperture now shows 1cm. How about a Checkbox in the Camera to let it either not scaled (as it is now) or to let it scale everything? I don't think the camera should generally adopt to the scene scale. If it would i could set scene scale from 1 to 10 and get completely different results if i don't match metrical scale by scaling the Object. @Niabot. Ich hoffe du siehst diesen Punkt. Wenn ich zum Beispiel eine 3d Modell mit Kamera von irgendwo in Blender lade und alles ist viel zu gross, kann ich mit dem Scale alles verkleinern, ohne veränderung der Kamera, bzw DOF. Ich wünsche dir (read You) einen schönen Abend. Gruss bashi %%%

Brecht Van Lommel commented

2013-03-13 18:17:02 +01:00

%%%Fix in svn, the camera focal length and sensor size show units now.%%%

Brecht Van Lommel commented

2013-03-13 18:17:02 +01:00

Changed status from 'Open' to: 'Resolved'

Brecht Van Lommel closed this issue

2013-03-13 18:17:02 +01:00

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Camera sensor size does not honor scene scale factor #34481