Problem with metallic shaders

[Cesar]

Hello to everyone

 

I'm working in a new image, is the interior hall of a building.

my problem is, all the interior walls are metallic, and the shader that i normally use, is taking ages to render, even with low settings in the material, the render time is so long!!!

And i have a good machine, at least is what i think:

dual quad core xeon 3.2 ghz and 8gb ram

I don't know what i'm doing wrong, or if this is normal.

the stage of the global illumination calculation is fast (irr, an lc) but the final stage, in the metal parts is the problematic.

If someone can gave me some tip, or parameter to recreate a good metal shader, i really apreciate.

i post the render settings.

 

In the material settings, even with just 8 subdivs in the reflections i had long render times (normally i use 50), i decided not use ward brdf, and the anisotropic in 00, to speed up the process, but not much success.

 

I put two images, one with the problematic view, and another from the access, to show how the material is.

[bijoy]

Hi there,

Im not really sure if i have the right solution but i do set things up a little bit different from you at the moment. first of all i think having metallic walls is generally gonna take u longer to render...i mean reflection on a lot of those surfaces is definitely gonna mean more processing. secondly, u are using hdri as environment lighting...that will eat up some more time considering u have metallic walls (correct me if im wrong here). ure hsph subd at 90 i think its a bit heavy. i normally set it at 50 and the interp samples at 30 and i keep my LC at 800. rQmc settings as min sample at 16...global setting at 4. Noise thres. i keep at default .01. i would suggest doin it the common way by adding a direct light for sun, vray plane lights at window/door openings and increase the samples for those lights to about 18 and get rid of the hdri. those i my settings and it normally works...i often use very low for irr map as well. if there is more noise then i would suggest increase the mettallic shaders sample a bit more maybe to 20. Hope this helps.

[Brian Smith]

i only got a sec so i will have to be short in the explanations...

 

biggest problem is the image sampler. it's not adaptive because you have left the 'use noise thresh' value enabled and the noise thresh value is set so low (0.003), every pixel is going to be subdivided 4 times. basically you are using a fixed image sampler when you set the noise thresh so low. but that value controls ALL blurry effects, which are many. i always disable the 'use noise thresh' so that I can control the noise in the adapt dmc/qmc sampler separately from the noise in all other effects. really it should always be disabled and i don't know why it isn't by default. i also recommend using a noise thresh of 0.01 (default) and maybe going as low as 0.005 if problems exist. but fix problems where they actually exist instead of using such an accurate global setting like this. also, always use adapt subdivs with default values for test renders and for production renders use adapt dmc/qmc with a min/max rate of 2/5 or 3/6 (if necessary for extra detail) and a clr thresh of 0.005

 

whenever you go below 0.7 on glossy/blurry reflections or refractions, I suggest using interpolation. the lower the value, the longer the render time and the more justified you would be in using interpolation. and the lower this value, the less difference you would see with and without interpolation. definitely use it in your scene.

 

also, your hshp subdivs is way, way, way too high. i almost always use 20 or 30. you would be getting more bang for the buck using a higher max rate than increasing this value to such high levels. if you have noise develop in your irmap, try increasing int samples up to 100 instead. it barely increases render times at all, relative to hsph subdivs.

 

if you dont need hdris, then try doing without them. using them (even properly) can add a lot of render time. i would only use them in low illumination scenes, and never for interiors. for interiors, they will have only a tiny effect on your scene (even with a lot of windows for the skylight to come through) but will add a lot of noise and potentially white spots.

 

always use vray light planes for interior scenes and position them just inside the glass of your windows (definitely not outside).

 

so much for being brief. oh well.

[Cesar]

Hi guys, I really really apreciate your comments and tips, i applied to my model with great results, i still tweaking parameters, but in general i´m gettin much much better render times with a nice quality. At this moments i´m delaing with some white spots, but i try to get rid of them.

In another forum a person told me that i should use interpolation in my material settings, thats help me a lot.

 

By the way brian, i,m curious about the vrlight inside the windows, this is not the specific case, but i used before. I model in archicad, and normally my windows has some thickness, When you say to put the light inside the window, is inside the room? next to the window, or between the two planes that conform the window thickness?