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vray and HDRI
show user profile  zeefusion
when rendering i get large white dots on a reflective metal material due to having a HDRI image in the environment slot. cant post an image as its commercial work, but it seems a common problem when i use HDRI maps.

is there a settings in Vray to tweak this so it doesnt come up with white dots? a quality setting or something?

im using irradiance map / min rate-3 / max -2 / hsph subdivs 50 / interp samples 20
Brute force subdivs 8 secondary bounces 3.

lights are 3 spots with inverse sqaure decay.

read 3609 times
4/14/2008 7:35:53 AM (last edit: 4/14/2008 7:35:53 AM)
show user profile  Bolteon
what version of vray are you using?

-Marko Mandaric

read 3603 times
4/14/2008 7:40:38 AM (last edit: 4/14/2008 7:40:38 AM)
show user profile  zeefusion
latest for max 2008 v1.5 sp1

it looks like its over reflecting the HDRI map and creating bright spots where it cant seem to reflect correctly. with HDRI map off it doesnt occur but obviously i dont get the reflecting effect i want as its a highly polished mateal material.
read 3600 times
4/14/2008 7:42:11 AM (last edit: 4/14/2008 7:43:58 AM)
show user profile  zeefusion
here is a section of my render sorry its small :) you can see the white dots i am getting on the reflective material

read 3593 times
4/14/2008 7:47:18 AM (last edit: 4/14/2008 7:47:42 AM)
show user profile  Bolteon
your a good deal behind in versions... the latest availible for vray is 1.60.19

there is an issue with the way vray interpolates pixels that are super bright (values much higher then 1.0 aka 255 aka white) when they neighbor too few a pixel that is of a drastic value lower...

what it causes is an unsampled rendered pixel where the reflection should be, it's feasible to sample the pixel enough so that proper shading occures but that would take ages.


you have two solutions:

- clamp your hdri in nuke or another program capable of properly editing 32bit files. your highest values shouldn't be over a couple hundred on a scale of 0-1. even for the sun getting past 5k is unceccesary.

- jump over to the latest vray, it has an option in the color mapping rollout that allows you to clamp rays being traced in render time before they're written to pixel data so you dont get the sampling issues.


also, make sure not to use the catmull-rom aa filter... it's causes what i think i might be seeing (small black rims around high value pixels). soften at 3 is the best bet.

-Marko Mandaric

read 3587 times
4/14/2008 7:51:46 AM (last edit: 4/14/2008 7:52:53 AM)
show user profile  zeefusion
thanx for that will give it a go.

didnt realise Vray has been updated. thanx for the heads up. has it been made for max 2009 also? as we received that today at work too.

*edit* on the chaos group site it says V-Ray 1.50.SP2 is to be released on 20th of April.??
read 3583 times
4/14/2008 7:55:17 AM (last edit: 4/14/2008 7:57:49 AM)
show user profile  Bolteon
you probably have to request the build from vlado/the team... it's production ready though.

-Marko Mandaric

read 3575 times
4/14/2008 8:01:47 AM (last edit: 4/14/2008 8:01:47 AM)
show user profile  mark_3d
hi dude, I finally got round to signing up haha :-)

hope you get it sorted. I havent seen this before so dont know how to help I'm afraid.

first post, what a useful one
read 3553 times
4/14/2008 9:21:22 AM (last edit: 4/14/2008 9:21:22 AM)
show user profile  zeefusion
a hoy hoy. good to see you some where useful for change. did you got your reflection issue sorted?
read 3548 times
4/14/2008 9:36:08 AM (last edit: 4/14/2008 9:36:08 AM)
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