kitchen shot

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SreckoM
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Re: kitchen shot

Post by SreckoM » 05 Mar 2012, 10:52

Yeah I hear you.
But I think that we are beating a dead horse here ....
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SreckoM
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Re: kitchen shot

Post by SreckoM » 05 Mar 2012, 10:56

@Kzin question for you, what is your opinion on buying MR standalone to be used with SI? It there any meaningful workaround that one can use? Will that give more freedom to user?
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Kzin
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Re: kitchen shot

Post by Kzin » 05 Mar 2012, 11:19

SreckoM wrote:@Kzin question for you, what is your opinion on buying MR standalone to be used with SI? It there any meaningful workaround that one can use? Will that give more freedom to user?
i dont know. from my knowledge (rendering with mental ray book), rendering with standalone means alot of command line commands.
if you think about it to overcome the integration problems, you will need to write alot of custom commands in bat files.
this could end up of several a4 pages of text. you could download the mr demo und try it by yourself, but you have to know all the commands which you need to call the ibl light for example and replace lights or shaders. its possible, but i dont think one second to do this, because i know the examples from the mr book. ;)
and also keep in mind, if you output the ibl from xsi for example, it uses the xsi geo shader also in standalone with all the problems. so the best way here would be to output the mi without ibl and insert the ibl thru commands in bat files.
someone with experience in that could give a more detailed awnser. perhaps in the mi forum, most of them uses custom commands and renders with standalone.

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Maximus
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Re: kitchen shot

Post by Maximus » 05 Mar 2012, 14:21

There is absolutely no chance a user or someone experienced enough can put hands on this geoshader problem? why is it so complicated to fix?
I have 0 knowledge of code and such, just wondering if anyone could do or it must be AD only, and why?

Kzin
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Re: kitchen shot

Post by Kzin » 05 Mar 2012, 14:50

Maximus wrote:There is absolutely no chance a user or someone experienced enough can put hands on this geoshader problem? why is it so complicated to fix?
I have 0 knowledge of code and such, just wondering if anyone could do or it must be AD only, and why?
from what i know, its the implementation of the shader in xsi, so the problem is xsi here.
i dont know if this can be fixed, but i think you have to rewrite the geoshader?
perhaps its possible with a native geo shader of mr, if you get it in. will take a look in the mr shader, perhaps a simple base.mi append brings in the native one (if the native one is already in xsi, then you have to change the code for xsi).

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ActionArt
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Re: kitchen shot

Post by ActionArt » 05 Mar 2012, 16:03

Hi Maximus,

Just saw this and don't have time to go through all that was said in detail right now but here's a couple things:

I use triangle filter set at 2 for stills. I've not gotten good results with anything else. Also, I never use unified. I've tried many times but never been able to get decent render times out of it and I don't like the results (for stills anyway). I just set sampling contrast at .058 with min 0 and max 2.

One thing is that you have very intense DOF. To do that MR has to do extremely high sampling so it's going to take a long time. I think the DOF is WAY too shallow, as a photographer you would never shoot it like that (unless it was for some very specific reason). At least your main center of interest should be fully in focus. Go lighter on the DOF` :)

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Maximus
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Re: kitchen shot

Post by Maximus » 05 Mar 2012, 20:42

ActionArt wrote:Hi Maximus,

Just saw this and don't have time to go through all that was said in detail right now but here's a couple things:

I use triangle filter set at 2 for stills. I've not gotten good results with anything else. Also, I never use unified. I've tried many times but never been able to get decent render times out of it and I don't like the results (for stills anyway). I just set sampling contrast at .058 with min 0 and max 2.

One thing is that you have very intense DOF. To do that MR has to do extremely high sampling so it's going to take a long time. I think the DOF is WAY too shallow, as a photographer you would never shoot it like that (unless it was for some very specific reason). At least your main center of interest should be fully in focus. Go lighter on the DOF` :)
Thanks for the feedback, both dof images were more like a test and i dont care that much, i know that they are wrong and it can be fixed and rendered better.
My only concerns are regarding the glossy metal and have a perfect clean glossy metal with mental ray, when your glossy is high as effect. This seems to be a problem to handle.
Not using Unified in my opinion is worse in this scenario, most of the time when i needed high quality images antialias 0 and 2 and rgb 0.051 wasnt enough at all. I had to use 1 and 2 and 0.02 on rgb with insane render times, many times even more.

In this case Unified is better, but it introduces a whole lot of other problems as described above, first of all the lack of understandable doc to support users. Now i'm getting different outputs depending on light sources, it appears that unified have problem with photometric lights sampling. There is alwas something that pops out of nowhere and causes problem. I have litterally to debug my whole scene and is frustrating.

Anyway not to start rant again, thanks for feedback everyone. Appreciated a lot, i will clean the scene and post for anyone that is willing to waste time on this.

Max

Kzin
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Re: kitchen shot

Post by Kzin » 06 Mar 2012, 12:08

Maximus wrote: Thanks for the feedback, both dof images were more like a test and i dont care that much, i know that they are wrong and it can be fixed and rendered better.
My only concerns are regarding the glossy metal and have a perfect clean glossy metal with mental ray, when your glossy is high as effect. This seems to be a problem to handle.
Not using Unified in my opinion is worse in this scenario, most of the time when i needed high quality images antialias 0 and 2 and rgb 0.051 wasnt enough at all. I had to use 1 and 2 and 0.02 on rgb with insane render times, many times even more.
raising the min samples because of one shader is always not that good because you double the samples mr renders in most cases. this ends in high rendertimes because every pixel of the image is sampled twice or more if you increas the low samples more. instead you should increase the local samples. to compensate oversampling for interreflection or refraction, use an raytype node for all secondary effects. its also a good idea to use a change range to change the samplecount over distance to aviod unnecessary sampling.
reflectionfalloff also helps to reduce the rendertime alot because you will not see details in a wide glossy reflection of objects which are far away.

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Maximus
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Re: kitchen shot

Post by Maximus » 06 Mar 2012, 14:11

Kzin wrote:
Maximus wrote: Thanks for the feedback, both dof images were more like a test and i dont care that much, i know that they are wrong and it can be fixed and rendered better.
My only concerns are regarding the glossy metal and have a perfect clean glossy metal with mental ray, when your glossy is high as effect. This seems to be a problem to handle.
Not using Unified in my opinion is worse in this scenario, most of the time when i needed high quality images antialias 0 and 2 and rgb 0.051 wasnt enough at all. I had to use 1 and 2 and 0.02 on rgb with insane render times, many times even more.
raising the min samples because of one shader is always not that good because you double the samples mr renders in most cases. this ends in high rendertimes because every pixel of the image is sampled twice or more if you increas the low samples more. instead you should increase the local samples. to compensate oversampling for interreflection or refraction, use an raytype node for all secondary effects. its also a good idea to use a change range to change the samplecount over distance to aviod unnecessary sampling.
reflectionfalloff also helps to reduce the rendertime alot because you will not see details in a wide glossy reflection of objects which are far away.
Hey Kzin, this is very interesting indeed, i've never thought how to avoid samplecount over distance.
Can you explain it a bit further on how to use this technique? scalar change range connected to glossy samples, and how you control the distance? Also what raytype node for secondary effects? I am debugging the whole scene step by step and it appears there is some issue on reflections caused by other things, not really samples.

Thanks again :)

Kzin
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Re: kitchen shot

Post by Kzin » 06 Mar 2012, 15:09

Maximus wrote:
Hey Kzin, this is very interesting indeed, i've never thought how to avoid samplecount over distance.
Can you explain it a bit further on how to use this technique? scalar change range connected to glossy samples, and how you control the distance? Also what raytype node for secondary effects? I am debugging the whole scene step by step and it appears there is some issue on reflections caused by other things, not really samples.

Thanks again :)
if you use high local samples, it would make no sense to render lets say 128 samples for objects that are near by the reflection because the object will not be that blurred like an object that is far away. so the idea is to say, ok, its near, so i need only 12 samples.
to do this, you need a scalar state set to raylenght. input this in a change range node. now in the change range, the old values means the distance in scene units and new values are now the samplecount. and this will be the input for glossiray value. in addition, take a look at the mia_mat paper from mi how you can blend between brute force glossi and fast interpolation. it can also help in some situations (i am not sure if i linked this to you some time ago?)

http://www.mentalimages.com/fileadmin/user_upload/PDF/arch_and_design.pdf


the other thing is the raytype switch node. you can change how different shaderrays are "seen" by other objects.
for glossishader it makes often sense to use the same shader with glossivalue of 1, because its reflection in other wideglossi shaders are blurred by default. so it can help to reduce computation time. you can find more raytype shaders under the native mental ray shader which give you much more options including alot of preprocessing tasks.
raytype and all the things are a old methods, but it comes up from time to time (i think harry aka saturn said this some time ago ;) ).

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Maximus
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Re: kitchen shot

Post by Maximus » 07 Mar 2012, 03:17

Ok here, let me try to explain what was my whole issue.

Basically i cant get a clean glossy effect when things gets reflected on that metal wall. I have no idea what is wrong and spent 2 days hiding/unhiding and rendering stuff. Still i never be able to fix this.

Here are the images:

Image

Image

Image

What has been tried:

- Glossy samples on all materials in the scene up to 256.
- All materials have Cutoff set to 0 in the optimization tab to avoid problems.
- Tried insanely hight unified/normal AA settings up to 1-3 rgb 0.01
- Tried to increase all lights samples up to 24
- Tried to relight the scene with just a point light
- Tried to recreate shaders
- Tried mia_material

Here is the scene, i kinda gave up.
There is something i'm doing wrong or it is just a bug. Clueless.

Thanks whoever can take a look and for help guys.

Max

http://www.2shared.com/file/MGDd5LhE/K_ ... share.html

Kzin
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Re: kitchen shot

Post by Kzin » 07 Mar 2012, 09:26

i will take a look on your scene on evening.

from you settings i think i know whats the problem, its not enough samples for glossis.
you have wide glossis and render them only with 2048 sample with adaptive aa, its simply to low. from my experience, you will need something like 0;3, treshold 0,05 and local samples set to 512 with distance change range optimization or perhaps with falloff from brute force to interpolation. i think this could work best here and it will renders alot faster then your current method.
also, unified will give you here alot of benefit because it renders the parts that needed it with much more samples and areas without alot of changes in shading with less samples.


for the lighting, the best way to get what you need is to shade in lambert mode with mia_mat (or arch_mat). you should always use this mat, its the mr version of the vray mat you always use in vray for example. it has some optimization regarding arealight sampling and in general optimizations for glossis. without to took a look on the scene, i am not sure if 16 samples are enough, portals has to bet set with enough samples, otherwise, you can get sampling problems without to know that the portals causes them.

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Maximus
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Re: kitchen shot

Post by Maximus » 07 Mar 2012, 10:00

Kzin wrote:i will take a look on your scene on evening.

from you settings i think i know whats the problem, its not enough samples for glossis.
you have wide glossis and render them only with 2048 sample with adaptive aa, its simply to low. from my experience, you will need something like 0;3, treshold 0,05 and local samples set to 512 with distance change range optimization or perhaps with falloff from brute force to interpolation. i think this could work best here and it will renders alot faster then your current method.
also, unified will give you here alot of benefit because it renders the parts that needed it with much more samples and areas without alot of changes in shading with less samples.


for the lighting, the best way to get what you need is to shade in lambert mode with mia_mat (or arch_mat). you should always use this mat, its the mr version of the vray mat you always use in vray for example. it has some optimization regarding arealight sampling and in general optimizations for glossis. without to took a look on the scene, i am not sure if 16 samples are enough, portals has to bet set with enough samples, otherwise, you can get sampling problems without to know that the portals causes them.
I'll wait for you to take a look at the scene but from what you've telling me that would take insane hours to render that scene.
My render in this thread was 8 hours and 40 minutes and i didnt have that high sampling.. Would it be 20 hours render for a so damn simple scene? I'm a bit speechelss :)
And i always use mia_mat for everything.

Thanks again for bein so helpful Kzin.

Max

Kzin
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Re: kitchen shot

Post by Kzin » 07 Mar 2012, 10:53

just to clarify this point, what is your system on which you render?
i have a z800 at work and only a quad 9450 at home, so i see some things different at work, rendertime wise. ;)

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Maximus
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Re: kitchen shot

Post by Maximus » 07 Mar 2012, 11:01

i have a 12core machine, intel i7 990xtreme clocked at 4ghz. 24g ram

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ActionArt
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Re: kitchen shot

Post by ActionArt » 07 Mar 2012, 15:30

The first thing I noticed was that your final gather settings seem to be reversed. Try swapping the rays and points setting. It should be more like 100-600 rays and 15 points or so.

One other thing. The maximum reflection bounces is too high. For glossy reflections like this I'd try 2 or 3 at the very most. If this is a still, you could use the reflection optimization in the Arch material to blur the reflections with a lot less samples. Try the default settings as a test.

Just testing now to see if that makes a difference...

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