Interior scene - Noise reduction suggestions


#1

Dear appleseeders,

I’m trying to render the following interior using SPPM.


The light diffusion is very nice but I can’t remove the noise.

I have trying the suggestions in: Why is my SPPM render that noisy? but I probably miss something.

I attach the blend file:
06-DoppiaAltezza_04-Appleseed-L.zip (20.8 MB)

Can you help me?
Thank you,
Rickyx


#2

First suggestion is to use the default Path Tracer engine. Stochastic Progressive Photon Mapping (SPPM) works well for scenes with complex light path chains (specular-diffuse-specular reflections) while your scene belongs to the category of complex visibility (much of the light emitted from the sources are not reaching the visible area). In a following post I will expand on these issues.
For now I attach the scene rendered with the Path Tracer (with and without denoising) and the render settings used. Additionally I changed some of the purely diffuse materials to Disney shader with 20% specularity to get more indirect illumination.

Denoised:

Without denoising:

Render Settings:


#3

Thank you Mango3,

I’m testing right now…


#4

Some more information on rendering interior scenes with appleseed:

appleseed currently supports two light transport algorithms, so which one best to choose?

  1. Unidirectional Path Tracing (similar to Cycles or Arnold)
  2. Stochastic Progressive Photon Mapping (SPPM)

This depends strongly on the scene. The default method to use is Path Tracing. It renders faster and is easier to set up correctly. However, if your scene contains lots of glossy reflections or caustics then SPPM is the better option. Path tracing has especially difficulties whenever there is a strong concentration of rays within a small region in space due to refraction or reflections on specular surfaces (caustics).

Unfortunately two major factors still limit the efficiency of many render methods: light transport by multiple highly glossy or specular interactions, and scenes with complex visibility between the camera and light sources (see image).

To repeat my comment on the thread https://forum.appleseedhq.net/t/why-is-my-sppm-render-that-noisy/533/9
The scene above is difficult for pathtracer because the room is only lit through a window from outside, most of the scene illumination is indirect.
The smaller the windows, the more difficult this gets to render. The (backwards) pathtracing algorithm emits rays from the camera into the scene until it hits an object and then needs to find a path to the light source. If the light source is small and difficult to connect to from the hit-point, the chance that a ray finds it is small .


#5

Thank you Mango3: using path tracer with your setup lead me to a very clean render. In fact is very easy setup.

Resolution 2048*2048px, rendertime ~10h):

And here is the file:
06-DoppiaAltezza_05-Appleseed-L.zip (20.8 MB)

I find calibrating SPPM quite complicated: I’m still trying to practice this “simple” scene…
Riccardo


#6

Very nice!


#7

Now add materials and a sky!


#8

Small update using Physical Sky:
06-DoppiaAltezza_05-LuxCoreRender-L-03


#9

Nice, could you post a larger image to be able to see the differences better.
I noted that you probably used the denoiser. There is an artifact at the bottom border of the image. This is also visible in my image with denoiser above.
The artifacts stem from a bug when using certain image sizes and denoise scales ratios which was meanwhile fixed in the current master version.


#10

This is a quick test: It may be that could be resolution issue as I just scaled dimensions to 15% … 317x317, not really a nice format for digital pictures :wink:

It is quite tricky to match the sky setup with sun direction…

I can’t get roughness map to work properly. I’m testing on sofa and floor.


#11

There is a function to lock the sun to the physical sky settings (vertical and horizontal angle) in the World Settings panel. But for this to work you have to add a sun light into the scene and then check the box: Use Environment For Sun Direction (see screenshot)

Capture

I can’t get roughness map to work properly. I’m testing on sofa and floor.

Look at this thread: https://forum.appleseedhq.net/t/roughness-map/560/6


#12

Thank you for the hint on sun.

For the roughness: I used “single output channel” (as in cycles “non-color data”) plugged on disney…
I’ll post a comparison.

…I’m finally on holidays… please wait some weeks :wink: