Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: valwizard on 2015-08-03, 10:36:52

Title: Depth of field issues with reflections
Post by: valwizard on 2015-08-03, 10:36:52
Hi all. I got an issue with highly reflective objects in foreground while using physical Corona DOF. The top of the foreground objects are still in focus which in real life camera will blur them according to a focal distance. Any suggestions?
Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-03, 10:52:24
The top of the foreground objects are still in focus which in real life camera will blur them according to a focal distance.
Are you sure? ;)
Take a mirror and put it reeeaaally close to your eye. Do you see the reflected objects far away blurred or sharp?

About noise: please show your render settings. What kind of lights are you using?
Title: Re: Depth of field issues with reflections
Post by: valwizard on 2015-08-03, 13:04:17
it does not matter - the eye will blur it because it will be out of focus- eye could not have in focus FG and BG at the same time. and camera as well. But thanks for lightening this. For example if you use dof in post instead - the dof will be right. Strange thing. The fake dof is more realistic than the real one.
Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-03, 13:54:12
I wrote that to encourage you to check it yourself in real life. But below you will find a picture I have taken myself a minute ago, the string is just for reference - it IS out of focus so the mirror is out of focus too. Only "bg" is in focus. :)

My argument in such cases is always the same - without it you would be unable to see anything when using SLRs or periscopes. They have a mirror inside, and it is very close to your eye, right? Or you can also imagine that every flat mirror is like a hole, in which you see flipped reality. :)

Conclusion: Corona's DoF is real, fake DoF is fake.
Title: Re: Depth of field issues with reflections
Post by: romullus on 2015-08-03, 14:02:54
And if you don't believe in pictures i recorded a video :]

Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-03, 14:11:51
:D

looks and works exactly like something filmed through a window

this thread should be linked every time a question like this appears (and I'm not complaining! I understand that this is counter-intuitive!)
Title: Re: Depth of field issues with reflections
Post by: valwizard on 2015-08-03, 14:37:33
Thanks Folks, it is really true. I have had no doubts in it. But the thing is - it LOOKS unreal. And after making an experiment with the mirror close to my eye and having the focus on background the reflections on the mirror Are blurred. So here is difference between the camera and the real human eye vision.
Title: Re: Depth of field issues with reflections
Post by: Stan_But on 2015-08-03, 14:41:00
it's looks real)
Just stop fantasizing about it and start to look on it)
Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-03, 14:50:24
Thanks Folks, it is really true. I have had no doubts in it. But the thing is - it LOOKS unreal. And after making an experiment with the mirror close to my eye and having the focus on background the reflections on the mirror Are blurred. So here is difference between the camera and the real human eye vision.
I'd suggest visiting an oculist.
Title: Re: Depth of field issues with reflections
Post by: valwizard on 2015-08-03, 15:36:02
Thanks, Maru. I will definitely follow your helpful advice.
Title: Re: Depth of field issues with reflections
Post by: valwizard on 2015-08-03, 15:49:15
Just a confirmation for those who like me needs an oculist visit. Those whos got a perfect vision please ignore my post
Title: Re: Depth of field issues with reflections
Post by: romullus on 2015-08-03, 17:03:55
In your first example reflection is blurry more due to rough surface of pavement than DOF. You can see this if you compare vertical and horizontal features in girl's reflection - see how horizontal lines are blurred much more than vertical ones? Also look at the man's in background head reflection. It lies in focus area, but is very blurry.
Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-03, 17:20:10
And in the second picture these are (neraly-)spherical reflections. They work completely different.
Title: Re: Depth of field issues with reflections
Post by: Ondra on 2015-08-03, 17:25:58

I hope I have some authority in rendering, so I would like to end this debate by saying that this video is correct ;).

Yes, you can focus on something in mirror without focusing on the mirror itself. If it were not possible, DLSR would not work, as you are observing the scene in viewfinder through a tiny mirror in front of the sensor.
Title: Re: Depth of field issues with reflections
Post by: valwizard on 2015-08-05, 12:50:06
Quote
And in the second picture these are (nearly-)spherical reflections. They work completely different.
This is what I am trying to figure out. Sorry if I sounded like a dumb. Thanks a lot for your help as it has cleared  a lot of my dark patches. I do my apologies guys for taking your time.
Title: Re: Depth of field issues with reflections
Post by: maru on 2015-08-05, 12:53:50
Dude, no problem! None of us is all-knowing! This forum taught me A LOT of things. For example, that sun doesn't get bigger as it sets down (which is kind of sad and kills some magic).