Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: ikifenix on 2015-09-14, 23:11:02

Title: Direct light resolution/accuracy?
Post by: ikifenix on 2015-09-14, 23:11:02

Hi, I have a problem with my scene, I have a room with a window (no glass) and a corona sun, the problem is: the shadows projected by the sun through window to the floor aren't accurate, specially in corners, they look rounded.

Searched in forum, corona web page, etc... but I didn't find an option or solution to that, sorry if it was answered before.

Example with sun settings, render settings are default:

(https://forum.corona-renderer.com/index.php?action=dlattach;topic=9459.0;attach=36174;image)

Title: Re: Direct light resolution/accuracy?
Post by: juang3d on 2015-09-15, 08:24:24

Have you tried reducing sun power? This shadow seems to be a bit burned and this can cause this type of "overflow" :)

Cheers.

Title: Re: Direct light resolution/accuracy?
Post by: Jpjapers on 2015-09-15, 12:05:57

Do you have a portal in your window?

Title: Re: Direct light resolution/accuracy?
Post by: Ludvik Koutny on 2015-09-15, 12:15:05

It's correct. Sun light creates slightly soft shadows, and since your scene is very overexposed, that softness is blown out and creates rounded appearance. That's how sunlight works and always worked in real world. If you decrease exposure and increase highlight compression, you will see softness coming back.

Title: Re: Direct light resolution/accuracy?
Post by: maru on 2015-09-15, 14:07:15

Yup, just confirming what Rawa wrote. Sun is area light, so it will always blur shadows like this. You can try changing sun size to some sick value like 0,01 and see what happens, but this will not look realistic.

Title: Re: Direct light resolution/accuracy?
Post by: Jpjapers on 2015-09-15, 15:20:37

its strange what doesnt look correct when you really analyse something despite it being accurate. i always think of that thread early on in alphas where someone built real lenses and stuck them infront of the max camera and they worked. It reminds me that if ive set it up correctly the corona is always right :D

Title: Re: Direct light resolution/accuracy?
Post by: ikifenix on 2015-09-15, 21:18:30

OK, thanks.

- jpjapers: No portal light, only corona sun.
- juang3d: Tanks, I will try that.
- maru & jpjapers: Thanks, so much years dealing with other renders where you have to set shadow bias, shadow resolution, etc... so when I saw rounded corners that was my first idea to fix it. After you answer... yes, it can be soft shadows + burn = hard rounded edges.

Title: Re: Direct light resolution/accuracy?
Post by: maru on 2015-09-16, 10:45:38

btw real life sample (photo)
https://focusgraphy.files.wordpress.com/2014/08/wpid-picsart_140924301287422-jpg.jpeg

Title: Re: Direct light resolution/accuracy?
Post by: romullus on 2015-09-16, 10:59:52

Bugs happens in RL too :/

Title: Re: Direct light resolution/accuracy?
Post by: Ondra on 2015-09-16, 11:53:38

Quote from: romullus on 2015-09-16, 10:59:52

Bugs happens in RL too :/

those are the worst, unrealistic clouds, weird shadows/caustics, unrealistic water surface, flickering on horizon, ...

Title: Re: Direct light resolution/accuracy?
Post by: maru on 2015-09-16, 13:52:40

classic

(http://new3.fjcdn.com/pictures/Bug+report_24ca39_4211290.jpg)