[Daniel Hruby]

I am hoping someone could have a look at this scene to determine if I have any obvious flaws that would slow down rendering. I have turned off displacement and things render much faster now, but this last image still requires over 26 hours on an 8 core MacPro w/ 7GB RAM to get a reasonably clear scene. I also tried turning off Multi light and still have to wait 26 hours to hit SL 16. Benchmark is a paltry 62. Scene has only 43000 triangles. I wonder if I need to use something other than Physical Sky? Or I have some bad material design, maybe my Mirror material? or the size of my maps?

Also, I do have some geometry in my model that overlaps. Like the glass tile on the wall slightly overlaps a material on the wall so the color shows through the glass. I have read that coplanar geometry has in the past presented problems.

My emitters are basically cubes. I am using Physical sky and in this case, multi-light is OFF.





Here is a link to the Pack and Go MXS. Its 136MB, so hopefully you have a swift connection!

http://web.mac.com/danielhruby/Maxwell_ ... hroom.html


Thank you in advance.

[Fernando Tella]

Hmm. If you can turn off physical sky and simulate with some emitters near windows it would help a lot.
Emitters could be planes instead of boxes.

[Bubbaloo]

What are your glass settings? If you are getting caustics generated, then that will definately slow you down with all the glass in your scene.
I agree with Fernando's advice. Use planes for emitters. A box is basically 6 emitter surfaces. Do you really need that?
Use AGS where the sunlight comes in. Don't use low or high grade glass.
Try using AGS for all of the glass and see if it acceptible.

On another note, you need a bigger wood map... Too many tiles!

[Daniel Hruby]

Thanks guys. I never use dispersion because it never cleans up on interior scenes. Glass Shower is using this MXM below. Windows are AGS. I have otyher glass like materials in there too though. Best thing to do is to look at the MXM's directly. I am at the moment going through trial and error hiding objects to try to find "heavy" materials.

[Bubbaloo]

I imagine it is all of that glass around the shower that is taking so long to clear up.

[def4d]

your render is inequally noisy, the wood is really clear but your walls and green panels are not.
I think it comes from their mxm, just an idea!

[Daniel Hruby]

I am fixing the lights now into planes. GLass shower is AGS now. Wall tile has an iridescent coating layer I will disable. Can't really see it anyway.


The wood is supposed to look book matched, so its not so bad the way it looks, but it would be nice to have some larger panels. Does anyone have any hi-res texture resources for large 4'x8' sheets of wood veneer / paneling? I wish Arroway would come out with a DVD on that subject.

More to come.....Thanks for any additional input from anyone!

BTW< What is a good ND setting for a mirror material?

[Bubbaloo]

nd of 20.

[def4d]

sorry for the misunderstood, i meant the wood was not noisy, not that it was bad!

[Fernando Tella]

Wall tile has an iridescent coating layer

That is really bad for noise. Coatings are always very hard to clean and spread reflected caustics noise all over the place. Good idea to remove it.

The shower glass should have a refractive layer or it will lose the effect of the curved glass, but you can also add a ghost layer to make it clean a bit faster.

Watch out also for materials with layers with too high unrealistic reflective value. It's easy to make over reflective materials with additive layer mode; that may produce a lot of reflected caustics and noise.

[tom]

Hi Daniel,

It's true that Maxwell is capable of simulating any situation. However,
it can take a lot of time and sometimes practically forever rendering some
compositions. Most of the time, optimum speed is a user magic. You need
to build your scene strategically to make it render faster. There are
numerous user materials around and I'm sure you have a lot of crowded
scenes in hand. When you load them and assign those materials directly
and design everything else -including lighting- like in real life, it may not
work. There's always a moderate level of translation needed between real
world and virtual world before starting to render. Every bounce and
transmittance of light is a speed killer for any engine. So, you need to
eliminate everything useless in your scene and simplify the materials with
maintaining the same look and sense. Although, it's only possible with
experience, so here we go.

I found the following speed drawbacks in your scene:

- Do not use high poly emitters, this is one of the best thing to reduce speed.
If they are planar, make them using the typical 2 triangles. Even when
they are circular, try masking the circular shape and use a planar emitter again.
In your scene, ceiling emitters have a lot of polys.

- Do not place emitters behind dielectrics especially if they are responsible
from main lighting. This means you're trying to illuminate the scene only
using caustics and it's another best thing to kill the speed. Again the ceiling
emitters are behind complicated dielectrics.

- Do not use real glass for window/door when making interior renders with
physical sky. These will collect sun caustics and increase noise in your
scene and it will help your render slow down. The door of bathroom on the
left of the cam is a subsurface frosty glass which is gathering sunlight off
from the room on the next. Horrible lighting scenario for sure.

- Avoid using high reflectances, especially when making materials using
Additive blending. Additive let's user exceed total reflectance with multiple
basics. Additive mode is helpful for making varnished wood floors etc. but
you need to make sure the base color and varnish color reflectances are
not additively amplifying the total reflectance. For example, such additive
white walls would surely make your scene look washed out with noise.
Personally, I'm suggesting Normal blending as much as you can.

- Do not use SubSurface with Additive blending mode. It's not supported
and will only produce noise.

- Do not use emitters in the unseen parts of your scene. For example,
the television using MXI emitter in the other room next to the bathroom
has no sense in your render. It will surely decrease the speed. Also
depending on its power comparing to the rest of the emitters in your
scene, this decrease in speed could be dramatically high. Simply, avoid
and hide them.

- Try to hide unseen parts of huge scenes as they will not be excluded
from the render progress. Because even a keyhole to the next room can
add many calculations. You wouldn't really want that. Hide the hills,
the garage and the other room etc. They will allocate space in RAM with
geometry and textures when rendering which will steal from calculation
space and probably from speed depending on your hardware.

Well, these are a few important points I clearly detected at first sight.
So, when you fix these issues, we can further think on what should we do
more to gain speed. As other friends also have said, that glass shower
cabin is not easy to render in a short time but, it's really not a primary
drawback and I suggest you not making it AGS immediately and try fixing
the above issues first.

Best regards,
tom

[Daniel Hruby]

Great post Tom. All makes sense and is a good check list for any render. I will go through my materials and double check all of these relationships and try to optimize for speed.

In regards to geometry, I am using ArchiCAD as the modeler and I am limited by the tools in some ways when compared to any other modeler. Alot of things are "canned" parametric objects. So, I have some limitations that require me to do some additional modeling. FOr example, tile grout joints are boolean subtractions from the floor surface becuse of a specific pattern around the bathtub edge. I rebuilt the lamps so that they are squares emitting down through a round opening. No dielectrics. And I adjusted the ND on the mirror in hopes of getting a decent reflection. Bubaloo suggested ND20 for a mirror. Any input on how to make a good mirror? I know it should be basic, but I have yet to see a specific mirror material appear on the MXM site.

Thanks again and I will update this post again when I get to the next round!

[tom]

Nd=20 is a good value for a mirror material. Less will make it reflect darker and more will make it reflect very even.

[Tim Ellis]

You can use a combination of glass and ags for the shower wall.

In your 3d application, seperate the glass edges from the front and back faces of the shower wall. Then assign a glass mxm to the edges and ags to the front and back faces.

This will give the look of proper glass, with the speed increase of ags.




Tim.

[def4d]

great tip Tim! Do you have a render that shows the result?