What is the problem ?

[bernhard]

Hello friends !

Today, I am working on a scene file, and I can't figure out, what I am doing wrong.

I get spots on the wall, you can see here:


I've increased the SubDivs and I also checked the secondary rays bias... but the spots are still here, and only in this part of the wall..

I use GI, Sun & Sky, Adabtive Subdivision, Irridiance Map: Medium, LC: 1200

thank you for every little help,
bernhard

[bernhard]

hmm, another test...

Well, this scene file is really funny, can't find any problems, but I still have the spots on the mesh.

I've deleted all of the the rest, every piece, and made another easy test render with the same material. I've created a box, to compare. The box with the same material is okay.

Look at this:


Well, is it the mesh ?
It's a File Linked Geometry - made with Revit.

But I really can't find any unusual at the surface from the mesh,or any trinagulation or what else. Even if I use the shell or push modifier on it - the problem is still there.

Any ideas ?

thx a lot,
bernhard

[DaForce]

Is there any textures on those pieces of mesh? if so try dropping a plain grey vray material on them.. like you have on the box.

Any errors in the vraylog?

Are you using vraydirt by any chance?

[bernhard]

hmm..

well, I've used the same vraymaterial on both objects.
No map in any channel, just a regular vray material.

No errors in the vray-log...
Hmm, haven't had such a situation in my render-life ...

Really weired.. any other ideas ?
thx a lot,
bernhard

p.s.: no vray-dirt anywhere else......

[DaForce]

are you able to post that those affect bits of mesh for me to look at?

[vlado]

You can try to reduce the "Normal threshold" for the irradiance map; if these details on the walls are actual geometry, this may happen with a large "Normal threshold" where the dark samples from within the closed details are mixed with the bright samples on the larger flat surfaces.

Best regards,
Vlado

[dominiquelaksmana]

i also have the same thing occured with every groveline i did.
not to be able to solve the problem with irrmap, i move to qmc/lc. rendertimes raised to 4-8times longer.

the only thing that came up to my mind is:
1. whenever you do a flat color wall, with groovelines, and you are using indirect lighting (afaik) such as : vraylightmtl, vraysky, environtment override, and you do it with irrmap/lc, that particular problems with splotches and blotches will come. i never found the exact reason. but this is the combination of things that brings the problems to the surface.

2. i have been asking this problems quite few times, i thought i had the answer, by using olli96's method, it helps alot, but not entirely. still have splotch and blotch. the bigger the resolution, the obvious it will be. so, instead of using vraysky, i went back to vraydomelight. sometimes combine with vraysky. or even i put an additional vray plane light, just to eliminate the blotches.

3. for a person like me and i hope not only me alone, with "low understanding" of technical terms, such as subdivision and samples, delone triangulation, max tree depth, minimum leaf size, face level coefisient, calculation parameters on lightcache, and i am still learning to be able to understand and implement the amount of each and every one of them, it's very hard, considering my limitation of time and energy(almost drained).

4. so Daforce, you are like my hero, bro (i am being an ass-sucker here, begging) please heeeeeeeeeeeeelp :P

[dominiquelaksmana]

sorry vlado,

i was typing when you reply , i didn't see. i will try that as well. thanks

[dominiquelaksmana]

IT WORKED!!
THANKS VLADO!!

[vlado]

Hm, if this is an issue that many people stumble upon, perhaps I can add an example for this to the help index...

Best regards,
Vlado

[dominiquelaksmana]

That would be Great Vlado.
i've been longing to know the real meaning and purpose of all parameters in the V_RAY rendering engine, and what does it do if i lower it, or make it higher..

regards,

[dlparisi]

Vlado: Does the normal threshold have any real world relationship to it's value? What does a value of ".1" mean for it? What I'm really asking is how much should we lower it - ".05" , ".01", etc. and is there any way to determine how much to lower it besides trial and error?

Thanks,
David

[teabag]

this sometimes hapens to me when i import the cad file in the scene....i usually notice somthing is wrong when i select a poly and it is not filled red , but some different color....the render then looks exactly like this

the only chance to get it right is to take the model save the selection...open a new scene and merge it back in...then it works...

...happens always everytime i import a dwg

[vlado]

Vlado: Does the normal threshold have any real world relationship to it's value? What does a value of ".1" mean for it? What I'm really asking is how much should we lower it - ".05" , ".01", etc. and is there any way to determine how much to lower it besides trial and error?

It is related to the scale of the details relative to the screen, but the exact error you may need for a particular case cannot be found in advance without some trial and error unfortunately.

Best regards,
Vlado

[bernhard]

Hello friends !

thank you all for your replies and suggestions.


@DaForce:
Yes, here is the max9 scene file uploaded for everyone to see this problem:

http://www.bernhardrieder.com/ask/spots.max

@vlado:
Thank you for helping us here - well, I also tried to reduce the Nrm Treshhold in the Irridiance map ... and it's a little bit better, but the spots are still there.

I am really wondering that it has something to do with the settings, because if I use a regular box, everything works fine.

As more as I think, there must be an issue with the imported mesh - and yes, I also could see this problem using the .dwg files from autocad, or from revit.

It's really strange. I mean probably it workes if you bind the mesh, save selection as... and after this you merge again... or you use an edit poly modifier ... but well, that's really a hard way if you have to use vray with autocad and revit for huge scene files every day.....

I hope we can find any solution for that.
Here is my last render from the scene file above....
the Nrm Treshhold in the Irridance Map was set to 0.001 - it's better now, but not really fixed....




thx for every little help,
bernhard