New Mental Ray shaders development

[Maximus]

max, are you sure you are using the right gamma correction?

did now tests with textures and colors from textures which i took in ps and used in si as color in diffuse reflection node.



the concrete texture has in middle a 50 to 60% grey. the grey sphere is simple color with 50 percent grey and they are the same.
for red i used a red color in diffuse node and a red color texture created in ps and rendered in xsi with proper linear workflow.
on top, one time the brich texture and under it the bright color i used in diffuse node and which i get in ps with color selector. and they are all the same.

I'm not using photo exposure, i've set the preference like this:



and usin render region, can u share that scene? i'm going nuts

[Kzin]

send you a pm,
and report if its work for you or not.

[Maximus]

This is how i setup my softimage

[Maximus]

I've opened your file and everything works like expected. Have no idea whats happening.

[Kzin]

i always use linear in color profile and put a color correction node between a texture and a color input.
can you try this. i never used the automatic option. other settings are the same, except i also check the fx viewers, but its for comptool only i think?

[Kzin]

I've opened your file and everything works like expected. Have no idea whats happening.

this is strange, can you send me a simple scenefile with your woodtexture so i can take a look.

[Maximus]

here is your scene rendered



gonna setup a scene for you

ps. i've added another red ball just in case lol

[Maximus]

can you try with this texture?

http://img201.imageshack.us/img201/659/77664320.jpg

in your scene try applyin to a sphere then get a mia material and set the weight to .318 i still cant match them..
Need to hold a bit, i'm quite confused atm.

I'm starting to think that its my textures and how they are exported from photoshop with color profile.

[rray]

Don't know if this works but for the light relative setting try this addon, should allow to set arbitrary string options...
__
*edit2* made a new thread about it, download and info is here

[Tekano]

whaaaat? havnt quite a few folk being asking Autodesk to implement this for quite some time? you should send them an invoice!

[Kzin]

here is the rendering with mila and mia with 0.318 for diffuse weight, booth spheres looks the same.

upper one is the mila, lower is the mia with divide by pi.



but i would not mix them two, there is no need for this. otherwise, i dont know whats wrong with your scene max.

[Maximus]

Alright, trying to shed some light.

Here is what bart says about this:

"Well, getting the lighting right, identifying them and using light relative scale is proving to be challenging. Sometimes they're physically falling off, sometimes area, sometimes not any of this.

We think we may provide a set of mila lights to guarantee the right light transport. This may be a second step."

"JJHop, light relative scale of 0.318 is what you want. Inside of mila, we will try to do the right thing hopefully based on knowing what kind of light is lighting. Currently, since most traditional light, transports light with a value pre-divided by pi, by modern expectations, mila inverts that light relative scale, therefore multiplying by pi.

If you cannot set light relative scale, try physical_light which does not have a pre-divided light tranport unit."

source: http://forum.nvidia-arc.com/showthread. ... #post44056

From my understanding: if you use mila material only in your scene you dont need anything, you dont need the light relative scale option, you need this only if you are using mila together with other shaders like mia etc.

He also says that getting the lighting right is quite a challenge, and this is what happened to me i think, because when i loaded your scene Kzin everything was working fine to me too, but after i made a new scene from scratch i had the issue back so i think its a randomness due to the fact that its hard to get the light right, as bart says too.

Now regarding the last bart words i'm confused again on if i should apply or not the multiply by PI or if hes just giving out a techincal information of what happens under the hood.
That said he admits that there gonna be some light setup for this, clearing out that honestly it wasnt implemented yet, hence why a bit of a mess on my part.

@kzin I am a bit burn out from tests and still a bit confused atm, on your scene with that colored texture everything works flawlessly to me too, but if for example i use another texture everything starts to be quite weird due to light intensity, its not a gamma problem i've tested it 100%.

So for now i'll just try to test with physical light only as you and bart say and see what happens, without multiplying the weight as i was doing before.

Ty for help


edit: just noticed that most of the "issues" i have with the shading is when i'm not using a physical light, portal light in this case gave me different shading, so i'll stick with physical for those shaders for now.

[Kzin]

dont know what went wrong. but in the ibl thread you wrote you changed your xsi renderpresets. have you tryed to restore the orig settings and tryed with them?

[Maximus]

dont know what went wrong. but in the ibl thread you wrote you changed your xsi renderpresets. have you tryed to restore the orig settings and tryed with them?

Yeah i tried that too, i've only changed filter type and some few things, didnt touch any serious had a backup tho.
What i'm noticing is that physical light is the most accurate one, and when i'm using it i have no issue, when i switch lighting set, even with portal is more "random"

[Kzin]

last idea would be to uninstall SI completely incl all user folders and reinstall it.

[Daniel Brassard]

if i should apply or not the multiply by PI

for mia and legacy shaders: apply the 1/Pi (0.3183)

for the new shaders like mila: don't, its already taken care of internally.

This is all relative to the texture you are using sRGB, Jpg, BMP texture have Gamma, EXR and HDR are linear.

Anybody tried EXP vs sRGB on the new mila?

Dan