Spots on Plants?

[Tommy L]

Doing an animation of a school and all going ok, except I have a problem with the plants. Theyre getting some strange spots on it. Ive tried all the usual avenues and cant isolate whats causing the problem.

Geometry is fine, Ive tried losing the smoothing and checked the faces.

Material seems ok. It has an opacity map but renders spotty without it.

Lighting is Irr Map only. Changing the settings doesnt help.

Any ideas?

[neil poppleton]

Tom,

 

What lights are in the room ?

[Tommy L]

I have a direct light coming through the top of the atrium (vray area shadows) and a vray light at the top in the glass part of the roof set to 'portal'.

But the plant material has no specular value, so I dont think its a highlight issue. Must be a sampling issue, but I cant find the relevant number to tweak.

[Brian Smith]

looks like a fungus...maybe Aspergillus candidus or Cladosporium sphaerospermum. but without more information i'm sorta shooting from the hip.

[johnvid]

looks like a fungus...maybe Aspergillus candidus or Cladosporium sphaerospermum. but without more information i'm sorta shooting from the hip.

 

Hey Brian I thought that was quite funny(must be my sick mind), but they sound like human conditions (asperges candida sperm & motherfxxxer), forgive me for pouncing but I could do with asking you a question about the free chapter in one of the books on vray on 3dats website...

 

The part where it says TURN OFF use QMC threshold, can you explain the logic behind that as I tried it and made the renders look worse, a lot worse than the image above, which your right about with out looking at the shader settings & light/render settings we may never find the answer.

 

In the maps for the plants, which filtering method is used. try none or summed area.

 

I have never tried to animate yet especially in darkish scenes with vray lights my renders always seem noisier, the floor looks like it isn't lit with any direct light and this plant looks like it has a little bit but in the direction of the light it can't be.

 

Maybe you could try the c.p.nich's example of using hidden white bounce cards to push more light into the scene or could the white walls themselves add a little more into the scene, as i can see some artifact on the wall in the far corner..

 

Or the easy way out, try a different plant for the close-up and move that plant to the other side of the room in the corner then there would be a nice shadow over there..

[Crazy Homeless Guy]

probably a long shot, ...but what type of material are you using on the plant?

 

off hand, it looks like that could be the color of the specular reflection that would have been preset to green, and maybe a reflective glossiness set to around .5 or using interpolated reflections.

[Tommy L]

Brian: didnt solve the problem but made me smile, so thanks.

John: forgiven

Travis: The material is a regular vray mat with an opacity map. No reflection value, so it cant be the interps.

[Chad Warner]

Could it be a geometry issue? Maybe the plant's doubled up?

[Tommy L]

Nope, tried that as well. Not a smoothing issue either...

[Tommy L]

Nope, tried that as well. Not a smoothing issue either...

[STRAT]

try replacing the light portal. (ie, dont use a portal)

[Tommy L]

Im quite liking th4e results Im getting from the portal. Do you not like portals?

[STRAT]

as a process? no. it's an unnatural way to light a scene i.m.o., and, not used correctly, can produce ironically slower render times and nastly samples/blotches.

 

have to tried rendering without the portal? do the plant problems still persist?

 

 

 

(all opinions expressed about lp's are personal only)

[Tommy L]

I havnt tried, but I will do. Its the first time Ive used a portal. I think the theory is sound, my understanding is from FryRender though. I think adopting a skylight generation with a smaller area to calculate makes sense and should provide a natural looking solution in this case. The render time is seven mins for the image attached and the test animation looks really slick, no blotching or anything and Im only using IRRmap in primary and no secondary illumination. AA at 2-3(AdaptSub area 1.5)

 

If its causing the spots it may be a problem though.

[F J]

hi,

since u'r using IRmap, have u tried gathering addicional IRmaps from a couple or so different angles (around the problematic area) n adding that to the solution merging the IRmaps?

[Tommy L]

Good idea, I shall try it.

[Brian Smith]

Hey Brian I thought that was quite funny(must be my sick mind), but they sound like human conditions (asperges candida sperm & motherfxxxer), forgive me for pouncing but I could do with asking you a question about the free chapter in one of the books on vray on 3dats website...

 

The part where it says TURN OFF use QMC threshold, can you explain the logic behind that as I tried it and made the renders look worse, a lot worse than the image above, which your right about with out looking at the shader settings & light/render settings we may never find the answer.

 

In the maps for the plants, which filtering method is used. try none or summed area.

 

I have never tried to animate yet especially in darkish scenes with vray lights my renders always seem noisier, the floor looks like it isn't lit with any direct light and this plant looks like it has a little bit but in the direction of the light it can't be.

 

Maybe you could try the c.p.nich's example of using hidden white bounce cards to push more light into the scene or could the white walls themselves add a little more into the scene, as i can see some artifact on the wall in the far corner..

 

Or the easy way out, try a different plant for the close-up and move that plant to the other side of the room in the corner then there would be a nice shadow over there..

 

the qmc noise threshold value controls noise for ALL glossy effects in vray, which includes motion blur, depth of field, blurry reflections, GI, and image sampling, just to name a few. by disabling the use qmc thresh option, you are telling vray to not dictate the noise accuracy by using this global value but rather by the clr thresh value in the image sampler. why would you want to do this? Simple. If you have a problem with image sampling, sure you can help it by lowering the qmc noise threshold, but you will be fixing problems that dont exist in other areas. By lowering the qmc noise threshold, you will apply better settings than what is needed for all those areas that are considered blurry effects.

 

image sampling is, IMHO, the most important area in any render engine. you should use the lowest possible values in this area that will give you the quality you need. you should borrow a value that dictates the quality in so many other areas.

 

btw, the only possible way that disabling this value could worsen your image is if the clr thresh value is lower than the qmc noise thresh value.

 

also, remember that if your clr thresh isnt set low enough, it doesnt matter how high your max rate is. like wise it doesnt matter how low your clr thresh is set to if your max rate isnt high enough.

[johnvid]

Thanks Brian,(and I am glad I was forgiven Tommy) I was kinda sure it must have depended on other issues, also, like perhaps vray lights & blurry fx.

But my noise thresh was about 0.003, and the lowest i have seen people take this seems to be .001 (CRASH)

 

adaptive value 0.85 min sample 12. global subdiv 2 or 3

I hardly ever use adaptive subdiv in the image sampler because its more prone to crashes (This to me indicates I have somthing else wrong too)

 

I will have to go over your response to digest it, and let it sink in (my head is in the wrong place at the moment to absorb it,due to spending far to long on a project and now finding that i may have to take the client to court to get paid) I feel that i may be over sampling sometimes but i am not seeing it in the quality, sure things look ok, but it doesnt seem to get better, (must ultimately be down to texture setups)

 

I always take multiple IR maps and merge them, but i am not sure it always decides the best samples to use..the more I am using IR, from hdri's orvray sun, I seem to be finding the difference between them, and just an over all flat colour in the skylight slot, is also up for debate, sure i like using them there is a difference but its perhaps just the final 20

 

I have tried many other settings in other areas from -6/0 -3/0 --3/-1 etc

calculating IR with and without AA

high presets/ highish subdivs (40/30, or lower 20/20) etc.

QMC GI 16/3

1/4 or 3/6 in the last rollout.

 

the percieved difference sometimes is negligable, but when i tried to disable that last ticker box it really deteriorated the render, more than anything else.

 

one question someone might be able to clarify is, if a materials subdiv is set to say 8, and then in the render settings you are using global subdiv multipiers, will it push the value up.. or would it be better to leave that material subdiv hi in the mat, and bring it down with the QMC subdiv, and other controling render settings.

 

I am sure its down to my use of other settings & I still have a long way to go to master this..

 

thanks john

[johnvid]

Hmm I kinda thought I had it, went over your explanation again, made more sense, but I think I am definatly over cranking my settings as it just crashes every time...

 

the trouble with all these setting being intertwined, in my own humble(and perhaps wrong) opinion, its all relative & inversly squarly associated, i think?

and sometimes the difference of the values is so small, changing it too much leads to all sorts of problems,

 

I have read all the cheat sheets/sampling pdfs & Vlado's universal settings (but cant even understand that, as it always crashes for me) (Quad core 4GB RAM)

 

I feel that changing say the bucket size, means certain other things should also change too. because if you have certain division settings and your bucket say is small, how could it devide the bucket up smaller than say a pixel...(without having say an over sampling setting in the min/max)

 

I suppose I will get there in the end, sorry to hijack the post.