Author Topic: DOF and Chromatic Abberation on backplate  (Read 744 times)

2019-12-06, 05:22:14

Alex Abarca

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Hi Corona Team,

I would like to add depth of field and chromatic aberration to the camera to match more or less the photographic effect of the backplate. Currently, If I were to add these effects on the camera it gets pre-multiplied on the backplate. I know I can solve this in post, but my question is directed in achieving this in the VFB.

Can we have an option to ignore DOF and Bokeh on the backplate. Or is it possible to do this now?
« Last Edit: 2019-12-06, 05:31:30 by Alex Abarca »

2019-12-06, 08:19:52
Reply #1

pokoy

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I've requested this a loooong time ago. Given that this is a rare request it hasn't made it yet into Corona. It would definitely be useful to have. 

2019-12-06, 10:44:24
Reply #2

GeorgeK

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You both raised an interesting issue, looking into it.
“Every artist was first an amateur”

2019-12-06, 11:03:07
Reply #3

pokoy

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Sounds great.

You'll probably want to hear of use cases to justify the dev time... For me, it was something I'd loved to have on every job when rendering against a real world photo plate. Especially in product renders, or mockups where you get a background with visible DOF. Using postproduction to compose the render over the original backplate is viable only if the rendered content is sharp everywhere. As soon as it gets blurred from DOF you'll have the problem that your rendered image will still have some info of the double-DOF in non-black alpha areas which can be problematic in post, up to the point where you can't get a good result depending on how extreme the Bokeh is.

If this is feasible code-wise I'd definitely use it on every render against a photo backplate.

2019-12-06, 19:13:21
Reply #4

Alex Abarca

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Rare to ask, yes it is. But the problem is quite common in corona rendering if you examine the images. I come across several images that are taken from the VFB where the model is shaper than background and this produces an uncanny valley effect.

Thank you Pokoy for adding your experience and your problem is parallel to what I've posted as an example.
« Last Edit: 2019-12-06, 19:17:14 by Alex Abarca »

2019-12-06, 19:18:57
Reply #5

shoebu23

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+ 1 to this request!

I get requests frequently to place consumer products into all sorts of photographs and I constantly run into this issue-- always handled in post.  If there was a way for the shadow-catcher material / backplate to be excluded from camera effects (DOF)- that would be amazing!

2019-12-06, 19:23:03
Reply #6

Alex Abarca

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It's probable that this image may present the same problem upon close observation. 
« Last Edit: 2019-12-06, 19:28:18 by Alex Abarca »

2019-12-06, 19:26:42
Reply #7

sprayer

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It is funny what if i am not mistaken v2 have bug to not blur background with DOF using standard bitmap loader ))

2019-12-06, 20:02:03
Reply #8

Njen

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Sounds great.

You'll probably want to hear of use cases to justify the dev time... For me, it was something I'd loved to have on every job when rendering against a real world photo plate. Especially in product renders, or mockups where you get a background with visible DOF. Using postproduction to compose the render over the original backplate is viable only if the rendered content is sharp everywhere. As soon as it gets blurred from DOF you'll have the problem that your rendered image will still have some info of the double-DOF in non-black alpha areas which can be problematic in post, up to the point where you can't get a good result depending on how extreme the Bokeh is.

If you know in advance that you will comp the image, then the image should always be rendered over black (environment primary rays not visible to camera). Then there is always no problems with anti-aliased pixels, no matter how much DoF or motion blur there is.

Personally I never understand why anyone renders over anything else but black, as the minutes it takes to put image A over image B in comp far outweighs the hours of re-rendering because you forgot something, or you needed to colour correct something a little.

I'd rather see that dev time go to towards actual limiting bugs in Corona.
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2019-12-06, 20:14:19
Reply #9

Alex Abarca

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Sounds great.

You'll probably want to hear of use cases to justify the dev time... For me, it was something I'd loved to have on every job when rendering against a real world photo plate. Especially in product renders, or mockups where you get a background with visible DOF. Using postproduction to compose the render over the original backplate is viable only if the rendered content is sharp everywhere. As soon as it gets blurred from DOF you'll have the problem that your rendered image will still have some info of the double-DOF in non-black alpha areas which can be problematic in post, up to the point where you can't get a good result depending on how extreme the Bokeh is.

If you know in advance that you will comp the image, then the image should always be rendered over black (environment primary rays not visible to camera). Then there is always no problems with anti-aliased pixels, no matter how much DoF or motion blur there is.

Personally I never understand why anyone renders over anything else but black, as the minutes it takes to put image A over image B in comp far outweighs the hours of re-rendering because you forgot something, or you needed to colour correct something a little.

I'd rather see that dev time go to towards actual limiting bugs in Corona.


Please don't derail the subject at hand. This conversation is not about post, its strictly VFB.

2019-12-09, 09:17:42
Reply #10

GeorgeK

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It's probable that this image may present the same problem upon close observation.

Ah no, for this I simply blurred the HDRI from texture map ^^ no DOF present.

Reported for consideration.

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« Last Edit: 2019-12-09, 09:34:56 by Corona_GK »
“Every artist was first an amateur”