Author Topic: Zdepth with Corona and PS  (Read 22111 times)

2015-02-03, 14:04:41
Reply #15

FrostKiwi

  • Active Users
  • **
  • Posts: 686
    • View Profile
    • YouTube
I'm not saying that the final result is incomparable in situations when DOF is slight but if you are looking to create images with the highest level of photo-real DOF and render times are not a huge issue then it's worth knowing the difference in the mechanism.
No, DOF is being rendered by Randomly placing samples in a radius around a given pixel and avereaging them, which takes a bullshit amount of time.
In post you just average the already existing data per pixel in a given radius. Disregarding Coverage and refraction, you get a 1:1 same exact result in both cases with 32 bit exrs or hdrs.
I'm 🐥 not 🥝, pls don't eat me ( ;  ;   )

2015-02-03, 14:51:50
Reply #16

Alessandro

  • Active Users
  • **
  • Posts: 323
    • View Profile
    • DotLab Srl
I'm not saying that the final result is incomparable in situations when DOF is slight but if you are looking to create images with the highest level of photo-real DOF and render times are not a huge issue then it's worth knowing the difference in the mechanism.
No, DOF is being rendered by Randomly placing samples in a radius around a given pixel and avereaging them, which takes a bullshit amount of time.
In post you just average the already existing data per pixel in a given radius. Disregarding Coverage and refraction, you get a 1:1 same exact result in both cases with 32 bit exrs or hdrs.

This is not fully correct. Try to get this very simple result in post. Of course maybe you can, but it's not so easy, it's hard just to imagine the result...
In most case I have no doubts, dof in render.
My Ducati or a render with Corona.....mmm, hard question!

2015-02-03, 15:03:44
Reply #17

Ricky Johnson

  • Active Users
  • **
  • Posts: 108
    • View Profile
No, DOF is being rendered by Randomly placing samples in a radius around a given pixel and avereaging them, which takes a bullshit amount of time.
In post you just average the already existing data per pixel in a given radius. Disregarding Coverage and refraction, you get a 1:1 same exact result in both cases with 32 bit exrs or hdrs.

Well, if that's the way Corona does it then agreed but I would have expected it to work similar to Vray which moves the camera
(again, this info I took from Chaos Group forum a few years back so I could be wrong but it seems like a logical explanation and I've always taken it to be the case).

If Corona is placing samples in a radius around a given pixel then you wouldn't be able to see through defocused edges on foreground objects to details beyond would you?
The system you're describing sounds like a simple type of blur.

2015-02-03, 15:06:19
Reply #18

Fibonacci

  • Active Users
  • **
  • Posts: 269
  • 3Dmanufaktura
    • View Profile
Hmmm....this case if you have an 32bit ZDepth pass, than you have a good chance to modifying the ZDepth's range, with simple use the levels modifier on it. Or to the 32bit passes use the  CameraRaw's CURVES.
Just convert to SmartObject, like always, then use Levels or Camera Raw and after use LensBlure. Try it. You will see, tha ZDepth pass is a really valuable pass in PS or Fusion or others...

Cheers mate!
Holy Corona : the materials is the clue.

2015-02-03, 15:13:54
Reply #19

Alessandro

  • Active Users
  • **
  • Posts: 323
    • View Profile
    • DotLab Srl
Hmmm....this case if you have an 32bit ZDepth pass, than you have a good chance to modifying the ZDepth's range, with simple use the levels modifier on it. Or to the 32bit passes use the  CameraRaw's CURVES.
Just convert to SmartObject, like always, then use Levels or Camera Raw and after use LensBlure. Try it. You will see, tha ZDepth pass is a really valuable pass in PS or Fusion or others...

Cheers mate!
Are you writing to me? In this case, enjoy yourself with the scene and try to obtain the same rendered result ;)

My Ducati or a render with Corona.....mmm, hard question!

2015-02-03, 20:14:32
Reply #20

FrostKiwi

  • Active Users
  • **
  • Posts: 686
    • View Profile
    • YouTube
I ment having the image being 32-bit, to have correct lightvalues for the bokeh.
Are you writing to me? In this case, enjoy yourself with the scene and try to obtain the same rendered result ;)
Challenge accepted
I'm 🐥 not 🥝, pls don't eat me ( ;  ;   )

2015-02-04, 11:41:45
Reply #21

Ondra

  • Administrator
  • Active Users
  • *****
  • Posts: 9048
  • Turning coffee to features since 2009
    • View Profile
Theory: Pinhole camera with no DOF shoots all rays from single point. Camera with DOF shoots ray randomly originating from a shape of the aperture (circle, n-gon, custom image). Only the ray origin moves, ray direction is constructed so that all rays for single pixel created from all positions on the aperture intersect in a single point in the focal distance.

Comparison: Rendered DOF is the correct solution with MUCH better quality. Post-pro DOF is fake with inferior results - but much faster, with the option to re-focus, so it is a tradeoff. Rendered DOF is better quality, postpro DOF is faster, siple. Deep data/OpenEXR 2.0 helps, but probably does not solve the problem completely.
Rendering is magic.How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2015-02-04, 12:18:26
Reply #22

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12711
  • Marcin
    • View Profile
There is also this. ;)
https://pictures.lytro.com/
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us