Page 3 of 3

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Mon Jan 07, 2019 1:00 pm
by CodeHD
B.Y.O.B. wrote:
Mon Jan 07, 2019 12:35 pm
CodeHD wrote:
Mon Jan 07, 2019 11:44 am
If it were, one could still manually place a larger enclosing volume if desired
But this would make the bounding sphere larger as well and you gain nothing.
No actually that was my point. As the bounding sphere is basically the smallest possible volume that encloses everything. You can then make it as large as you like by creating a "box" as discussed before.

In some sense this is equivalent to the current situation, as you can create a "bounding sphere" by that manually placed "box" as discussed.

My thought here is that placing the sky on the bounding sphere might yield a more intuitive default result (a Sky that is visible through a mildly homogeneous volume vs. a black sky), while at the same time saving a bit of effort of setting up too many volumes.

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Mon Jan 07, 2019 6:16 pm
by lighting_freak
Hi all,

this is the same *.blend file than before only the camera volume has been set to the diffuse one, that I'd like to have inside the room.
As you could see it directly influences the visiblity of the sky outside the windows. It becomes foggy.
10 Samples only - sorry for the noise
10 Samples only - sorry for the noise
Diffuse_World_Volume1.blend
(1.24 MiB) Downloaded 81 times
Is it a bug?

BR

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Wed Jan 09, 2019 8:21 pm
by Fox
Seems like with the type of hetero scattering volume, the camera can see out of window.

There are hdr and textures included, that's why 500 MB.
https://drive.google.com/file/d/1_VwlnP ... sp=sharing

Window frame and glass is splitted in 3. Interior for dust, exterior for clear and whats between them a glass.

Here is 5 min or so preview
Preview.jpg

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Sun Jan 13, 2019 11:09 pm
by lighting_freak
Hi,

thanks for the sample file. I really like the result.
I do like the setup as well, but unfortunatly I don't understand the parametrs that were used in heterogenious volume definition.
I still don`t understand why it works with this volume type and why it doesn`t do the trick with a homogenous volume.
I hope you can help me one more time.
Thanks.

BR

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Sun Jan 13, 2019 11:59 pm
by Fox
I don't know the volumes very well myself.
If possible at all the homo volume with multi off is much faster than hetero.

Maybe some other setting is wrong. The scene epsilon is worth testing.
I have this other scene where rendering passes sample/sec gets lower and lower over time, but rays/sample does not.
When i set the scene epsilon smaller, the volume is not dull any more and the render passes speed does not drop slower 10, 100, 1000 times over time.
Al so every next auto saved exr and png has different file size, compared to previous save.
It was CPU embree render in standalone LuxCore where the volume has size 2mm x 20mm x 20mm
absorption is mixed between 0.3 to 0.000003 at the depth of 0.0015
scattering is mixed between 1 to 100000.

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Mon Jan 14, 2019 9:50 am
by Dade
Heterogeneous volumes have a "max. step count" parameter limiting the total number of steps inside a volume (to have a cap to the computation). The result is that any heterogeneous has a limited extend in order to not have an infinite computation.

It is about the same of having placed the homogeneous colume inside a sphere (only more far more expansive to render).

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Mon Jan 14, 2019 5:13 pm
by Fox
Is the step count 1024 overkill for dusty room?
The step size of 1 meter is probably good speed improvement from 0.1 meter.

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Mon Jan 14, 2019 5:28 pm
by Dade
Fox wrote:
Mon Jan 14, 2019 5:13 pm
Is the step count 1024 overkill for dusty room?
It is a lot of steps for sure but it depends of how heterogeneous is the volume (i.e. if it is homogeneous, even a single step should be enough).

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Wed Jan 16, 2019 4:46 pm
by lighting_freak
Hi,

Thanks for this information.
If I got it right this heterogenious volume parameters create an incredible advanced variant of the null- material-box solution that was discussed in threads before...

I still don't understand why a camera that is placed in an homogenous volume can't see the sky behind a window.
I'm really dependent on having correct volume interactions. My workflow is usually that I make material setting according to real world data and trust the result that lux render creates...

I'd you need a more simple test scene let me know.
Thanks a lot.

BR

Re: Want to have a diffuse air inside a room and clear air outside

Posted: Thu Jan 17, 2019 4:05 am
by Fox
Can it be the bi-dir likes ray-marching that heterogeneous has?
Anyway here is heterogeneous with step size 0.5 and max steps 32 (almost like homogeneous in terms of speed).
Hetero Vol 0.5m 32Steps.jpg