Light Cache and IR map problem

V-Ray for 3ds Max V-Ray for 3ds Max :: Issues
1

Hi everyone,

Im having a problem using light cache with irradiance map, im not sure if it is a bug, or if its something im not doing right.

This first image is the Light Cache calculation, it looks good

This second image is during the Irradiance map calcualtion, it looks too dark

This third image is the rendered image with 1000 light cache samples, it looks like it hasnt renderd the secondary bounces.

This fourth image was rendered with 700 light cache samples and everything rendered fine.

If anyone has any suggestions please let me know

2

Yeah i had the same problem today .. i thought i was going mad .. obviously not.. and it was due to invalid lightcache samples… what caused i dont know as yet.

3

Thanks for reply Natty, I thought i was going nuts too

hopefully Vlado has an answer

4

It would seem that the light samples become corrupt and unusable and then vray doesnt have a second bounce calc? odd ..

5

Make sure that your light cache sample size is set to a larger 0. After playing around with PPT I discovered that calculating a single frame light cache map with a sample of 0.0 results in an invalid light map. So I returned the sample size back to default and all is fine.

The only problem is that you cannot save an unbiased light map (sample size 0.0) when using the PPT method. You have to set the sample size to .000001 or something like that.

6

im getting this without using PPT .. this is just lightcache..

7

yeah same here natty, my sample size was set to .01 and it was just light cache

8

Does this only happen at 1000 samples?

9

I agree there is something going on. I did into a similar problem as you guys last night. I was just able to reproduce the problem when setting the sample size to zero. So, I know it’s possible to encouter this simliar if not same problem if people are changing the sample size zero and forgetting it there. After setting the sample size back I have not had a problem since…

How are you guys calculating your light cache map?

10

1000 and above

11

You probably get an invalid color somewhere along the process, which then propagates throughout the scene and sucks up all of the lighting (that’s GI for you :-)) Look at the VRay messages window to see if you are getting any “overbright or invalid color” warnings.

Best regards,
Vlado

12

ok, thanks for that Vlado,
What is the best way to get rid of overbright o invalid colours?

13

… well im getting an overbright and invalid colours on every object in my scene all of a sudden ?

14

I also noticed that overbright or invalid color warnings seem to increase in amount when lightcache samples get smaller…

15

I’ve been getting random overbrights as well - may or may not be related but I especially took a major hit (a big list of them) when I switched over to IR Buckets when rendering DR. Rmove the ‘buckets’ and it went away…

16

The reasons for the invalid colors may be several: missing UVW coordinates (to a large extent this is corrected for the next release), invalid UVW coordinates (applying cropping to the bitmaps usually helps), the Ward BRDF in some cases (this is corrected for the next release), RPC objects under some conditions (they need some Reflection option on or off not sure which one).

Best regards,
Vlado

17

I too just had this occur. I have rendered this scene a dozen times and now all of a sudden I am getting massive overbright and invalid colors with the Light Cache. Once I get them the whole scene turns nearly white. I cannot figure out what I changed that caused this. When I revert the scene back the way it was when it last rendered correctly it is still doing it.

18

After much searching I fixed the problem by removing a displacement mod from an object that was intersecting geometry. I can live without it, and it seems to have resolved the issue.

19

vlado,

are there any other solutions to this issue? when do you expect the next release?

20

That particular thing can probably be solved by applying the “Crop” option to the scene bitmaps.

Best regards,
Vlado