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PM revisited

General discussion on lighting, backgrounds, Global Illumination, rendering parameters and tonnemapping.

PM revisited

Post Tue Jan 31, 2017 7:20 am

Hi Samo,

I know this matter has been given a lot of attention already, but still if you have some spare time can you tell me what's causing the ugly spotty pattern on the floor of the attached render?

The settings are actually based on the numbers you gave on this forum a couple of years ago, except I cranked the photon amount to 3000000 (the more the better, right?).

By the way, the fireflies won't go away even after 32 AA passes (light samples for the lamp and candle are at 128)... :(
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Library_photon map_32lightsamples_settings.png
maverick
 
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Re: PM revisited

Post Tue Jan 31, 2017 8:13 am

Hi

First to see the quality on the photon map you should enable the "show radiance map" setting to see whether there is a homogeneous distribution of indirect lighting across the scene, without black patches.
You have more information about photon mapping below:
https://docs.google.com/document/d/1OZF ... sp=sharing

Secondly, the white fireflies are probably produced not by photon mapping but by the direct lighting integrator sampling one of the light sources which is too close to a mesh, either the light sources on the wall or the ones into the lamp. This is a known difficult case for raytracers and the only way to solve it is with more AA sampling and light samples.
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Samo
 
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Re: PM revisited

Post Tue Jan 31, 2017 3:10 pm

Thank you, Samo.

Can you tell if the following radiance maps are homogenous or not? I'm just not sure I can read them.
Attachments
30.01_radmap_02.png
30.01_radmap_01.png
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Re: PM revisited

Post Tue Jan 31, 2017 6:09 pm

If I'm getting this right, for search radius of 0.01 the amount of photons shoud be about 50 million? Is 350 the max value for search count?

P.S.

I couldn't find these details in the tutorials.
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Re: PM revisited

Post Wed Feb 01, 2017 7:27 am

Hi

There is a clay render feature that you should enable as well with "show radiance map" to see the quality of the photon map without material colors interference. Anyway the photon map you show is already good.

Radius is related to scene units, if in your scene 1 blender unit = 1 meter, this would mean that radius=0.01 is in fact radius = 1 cm., which is too much for photon mapping and will require a lot of photons. In interior scenes with that configuration I usually work with radius = 0.10 or 0.15

Between 150 and 350 is a good value for search count
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Re: My point of view on YafaRay development

Post Tue Feb 14, 2017 6:57 pm

I needed to make a wood material, and habitually (having some expr. with Cycles) used the diffused material. In the picture I positioned mesh lights against the bannisters, corbels and walls, to show the reflections (in the upper part, on the curved moulding, there are many of them).

Samo already recommended to use Glossy, and it worked (second picture). But in it's current version glossy looks a little bit different. It would be nice to have a choice btw diffuse and glossy for such situations.
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Library_upper part_dirl_caustics_10.png
Library_upper part_dirl_08.png
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Re: My point of view on YafaRay development

Post Tue Feb 14, 2017 7:03 pm

By "different" I mean darker, and kind of wet. Of course there's a good chance it has more to do with my skills than with the shader.
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Re: PM revisited

Post Thu Feb 16, 2017 7:24 am

Just to sum it up,

final gather sampels parameter doesn't influence the detail level at all (in Photon Mapping, as opposed to Pathtracing)? It's all about diffuse search radius?
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Re: PM revisited

Post Thu Feb 16, 2017 9:39 am

Photon mapping only calculates indirect lighting contribution. Final gather is basically a path tracing algorithm limited to one bounce that interpolates photonmapping results, but it produces montecarlo noise which is bad for detail. You need FG more samples to get rid of noise.
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Re: PM revisited

Post Thu Feb 16, 2017 11:53 am

Thank you.

Let's say I want to see the roman numeral on the clock dial. Do I need to increase the FG samples, or decrease search radius (everything else, like lighting, etc., being equal)?

By the way, the Pathtracing also has that realistic look, same as PM (even with caustics turned off). How does it do it without indirect lighting sampling?
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Re: My point of view on YafaRay development

Post Fri Feb 17, 2017 7:05 pm

Hello,

I'm not sure if this is similar to what you want to achieve, but just in case have you tried to map the wood texture also to the bump map, for example, to get a more realistic reflection?

For example:
possible wood.jpg



You can do it quickly and easily mapping the texture to the bump as follows:
possible wood material.jpg


I hope it helps somehow...
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Re: My point of view on YafaRay development

Post Sat Feb 18, 2017 9:34 am

Hi David,

I knew about the bump feature, just didn't have the time to tinker with it (well, I used it on other materials, just not on wood yet).

Here's what I've come up with so far.

15.02_01.png


And this:

16.02_01.png


Photon mapping is a great render algorithm, but I need to learn so much more to use it efficiently.

I guess the wood material is no big issue, I can make do with the current shaders.

Metal, though, is really difficult to emulate.
Last edited by maverick on Sat Feb 18, 2017 3:57 pm, edited 1 time in total.
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Re: My point of view on YafaRay development

Post Sat Feb 18, 2017 9:52 am

And a couple more takes (they look wrong somehow):

17.02_01.png


17.02_02.png


17.02_03.png
Last edited by maverick on Sat Feb 18, 2017 4:00 pm, edited 1 time in total.
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Re: My point of view on YafaRay development

Post Sat Feb 18, 2017 9:57 am

This doesn't exactly relate to your vision of yafaray development. I can move these posts to a different thread, if needed.
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Re: My point of view on YafaRay development

Post Sat Feb 18, 2017 6:59 pm

maverick wrote:This doesn't exactly relate to your vision of yafaray development. I can move these posts to a different thread, if needed.


Hello, maverick.

I've moved these posts here, I think it's a better place for them. I hope you agree ;-)
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