View topic - Could use some critique and help with GI

Could use some critique and help with GI

Post here general questions about usage of YafaRay and about the Blender Exporter UI

Could use some critique and help with GI

Post Wed Aug 05, 2009 6:37 pm

Hello, I'm new to using Yafaray, but have been using Blender for a few months now. I'm in the process of modeling my house, and I have the whole first floor done. I'm in the process of rendering stills from each of the rooms from a few angles, but I'm having a hard time getting Global Illumination (Photon Mapping) to work for me without being very dark, and grainy.

I've tried as many as 4,000,000 photons with 320 Final Gather samples, but it hasn't seemed to help. I have a sun with 2.0 for energy, Area lights at all four corners of the house, and 6 spots in the kitchen as recessed lighting. Attached is s the room with Direct lighting, and lower light energy settings than listed above and one with Photon Mapping.

Any help for a Yafaray newbie would be greatly appreciated. Also, this is the first model I've done that I've posted anywhere, so input is also appreciated.

kitchen_direct_light.png
Direct Light


And Here's one with Photon Mapping...
kitchen_gi.png
Photon Mapping
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rubylaser
 
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Re: Could use some critique and help with GI

Post Thu Aug 06, 2009 7:12 am

can you attach a stripped down version without funiture, only walls and floors and light sources, please.
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Samo
 
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Re: Could use some critique and help with GI

Post Thu Aug 06, 2009 12:49 pm

Here's a stripped down version, sorry that I couldn't get it any smaller than it is. I goofed around with this last night, and again this morning, and I'm guessing that it has more to do with my lighting setup than it does my Photon Mapping settings, but I could be wrong :)

http://rapidshare.com/files/264360089/kitchen_lighting_config.blend.zip.html

Thanks
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rubylaser
 
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Re: Could use some critique and help with GI

Post Fri Aug 07, 2009 12:36 pm

Hi this is my first try, I will come up with more.

I have changed many things, mainly sampling strategy, spot lamps, the downlights are not longer mesh light but a shinydiffuse with emit, and I have started with this simple night scene, later I'll post some daylight.
Attachments
kitchen_lighting_config2.zip
(357.64 KiB) Downloaded 375 times
render1.png
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Samo
 
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Re: Could use some critique and help with GI

Post Fri Aug 07, 2009 6:37 pm

Thanks for doing this. This looks much better, and I can actually start to understand how to set this up properly. I eagerly await a day scene so that I can try this out on my final furniture model.

Thanks again
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rubylaser
 
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Re: Could use some critique and help with GI

Post Sun Aug 09, 2009 12:31 am

This is a second test. I'm using arealights to simulate skylight. I would like to try another test with true background lighting.
Attachments
kitchen_lighting_config3a.zip
(271.87 KiB) Downloaded 391 times
render2.png
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Samo
 
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Re: Could use some critique and help with GI

Post Sun Aug 09, 2009 11:31 am

This looks very good. I appreciate you taking the time to set this up properly so I can see how this works. I can see that my long area lights were a bad idea (fewer light sources, and wasting protons on the outside of the wall).

I would really like to see one last one with real background lighting.

Thank you
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rubylaser
 
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Re: Could use some critique and help with GI

Post Mon Aug 10, 2009 2:10 pm

here with the background lighting, it needs more sampling that the ones before, that's why the sampling strategy is different:
Attachments
kitchen_lighting_config3a.zip
(273.34 KiB) Downloaded 431 times
renderb.png
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Samo
 
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Re: Could use some critique and help with GI

Post Tue Aug 11, 2009 11:13 am

Thank you for spending the time to set these up for me. Attached is the result of the background lighting example (the third), I will post examples of the other two today as well. This looks great, other than my stainless steel texture, and the back of my stools are pretty grainy looking and the image has a little grain overall. Also, I noticed that a pixel in the wood floor didn't get rendered for some reason.
Attachments
kitchen_area_light.png
Area Light
kitchen_background_lighting.png
Background lighting
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rubylaser
 
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Re: Could use some critique and help with GI

Post Tue Aug 11, 2009 9:45 pm

The pixel not being rendered is do to the (in)famous black/whate dot issue. (see other topics in this forum)

Try changing the sampling parameters and see if it goes away.
Hyperspace
 
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Re: Could use some critique and help with GI

Post Wed Aug 12, 2009 1:16 am

Thanks Hyperspace for your answer. I found a few posts mentioning what you are talking about. It's tough to spend hours rendering to potentially have a flaw like this. I've just got to practice more with Yafaray to hopefully avoid this in the future. But, in this case, I only have the 1 spot, so Photoshop will be a quick fix :)
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rubylaser
 
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Re: Could use some critique and help with GI

Post Wed Aug 12, 2009 5:08 pm

Yep it is a bit frustrating, but hopefully it will be fixed soon.
Hyperspace
 
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Re: Could use some critique and help with GI

Post Sat Sep 05, 2009 1:26 am

Samo

2 questions:

1. Why do you use the emit of a material instead of meshlight. what is the reason for it?
I noticed in a comparison that the emit light seems to be double as fast.

2. The last scene you posted seems to be the same like the second one.

I was curious to look into how you set the different sampling strategies but well since the scenes
are the same I cannot compare them.

Could you upload the third version again?

Claas
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cekuhnen
 
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Re: Could use some critique and help with GI

Post Sat Sep 05, 2009 8:29 am

Hi Claas,

You have to load the set of render settings called 'Photon'.

In the second render, an arealight is used to simulate sky light. In the third render I use the background to simulate skylight. It gives a more realistic result, but it requires more sampling.
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Samo
 
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Re: Could use some critique and help with GI

Post Sun Sep 06, 2009 6:06 pm

Hi Samo,

well I know that you need to use the Photons. I was just curious about the sampling values
you would have used.

In the manual they say:
Emit objects can be used as diffuse light sources, but you will have to use it with path tracing or bidirectional path tracing lighting methods.

but than you use photon mapping. the emit light does not distribute photons or why is it suggested to use path tracing?
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