Double sided surfaces and rendertimes

[sentry65]

I have a very large scene that was given to me to texturemap and the surfaces do not need to be double sided.

What I was wondering though was, does a double sided suface only increase rendering time if the camera sees the other side of the surface and must calculate it or do both sides consistently get calculated?

It would take me 5-6 hours to make things single sided and so do you think it is worth the time?

what about things like refraction and reflections if raytracing is not going to be used? is there any boost in speed by having an object not reflective/refractive from the start is the renderer smart enough to know to not even look at that attribute if the render globals are set that way?

thanks

[deke-kincaid]

What I was wondering though was, does a double sided suface only increase rendering time if the camera sees the other side of the surface and must calculate it or do both sides consistently get calculated?

It renders both side no matter if you see it or not.

It would take me 5-6 hours to make things single sided and so do you think it is worth the time?

Why would it take you 5-6 hours to do this? You can do this in seconds to everything in your scene with the attribute spreadsheet.

what about things like refraction and reflections if raytracing is not going to be used? is there any boost in speed by having an object not reflective/refractive from the start is the renderer smart enough to know to not even look at that attribute if the render globals are set that way?

I'm not sure I understand this last part. Maya is a selective raytracer. It only raytraces reflections/refractions on objects that you tell it to and yes not having an object reflective/refract will speed up things alot. Scanline rendering is always faster than raytracing.

Deke Kincaid

[axislg]

I think this fella is just looking at the render stats node and asking what needs to be changed here to make render times faster.
I doubt that turing reflections refractions off here is going to speed anything up here if you do not have raytrracing turned on in the render globals....furthermore to speed up your rendering look deeper into the f1 supprt files and also do an automatic optimizer. How large is your scene megaytes wise?.....I am notorious for finding workarounds for render optimization....if you forward it to me via email I might be able to help you further.

[sentry65]

thanks guys, I actually never tried using the attribute speadsheet and am now glad I was introduced to it.

Let me rephrase my question about double sided vs single sided. Do double sided surfaces take longer to render than single sided ones if you never see the the back side of the surface?

all the surfaces in my scene can most likely be single sided, but the problem is the normals are not all facing outward so I'd have to check every part.

Another question kinda similar:
the guy who built this scene for some reason modeled all the nurbs with a degree of 1 in the U direction. I'd like it to be 3 but don't want to do a rebuild surfaces on each object one by one. Is there a way to make it render to the 3rd degree so it renders curved?

[joojaa]

In reply to:
Let me rephrase my question about double sided vs single sided. Do double sided surfaces take longer to render than single sided ones if you never see the the back side of the surface?

Yes, a signlesided surface that is facing away only uses as much time as it takes to test if normal is thisway or thatway.

Ok to explain tis you need to know how the renderer basicaly works (ok there are other optimisations too but youll get the point): All surfaces that lie so that they might contribute to a pixel are calculated, and the one that is the foremost will be finaly asigned then we test the next pixel(or subpixel). The z value of each pixel is then used to determine the order of theese surfaces (this is why the precission can suffer if your scene is lerge as the z buffer is numericaly limited).

Now if a surcace is facing the other way around it wont contribute to this calculation as it can be easily omitted form the calculations before we begin. Therby saving many cycles of unneccesery calculations.

In reply to:
all the surfaces in my scene can most likely be single sided, but the problem is the normals are not all facing outward so I'd have to check every part.

Yes im a fraid so, first check tow sided of for the whole deal. Then make your view backface culling and then swap those surfaces that point the wrong way.

In reply to:
the guy who built this scene for some reason modeled all the nurbs with a degree of 1 in the U direction. I'd like it to be 3 but don't want to do a rebuild surfaces on each object one by one. Is there a way to make it render to the 3rd degree so it renders curved?

Umm... This is a stupid question but why dont you modell your surfaces as 3 degree curves. And then just selct your surfaces and hit the "1" button for lower resolution, or select view nurbs smoothness hull? Which is essentially the same resolution as for the 1 degree surfaces.

But thisway you can toggle between smoothed look and hull look as much as you like, you might need to (see the smooth result while modelling but not while animating). Just select the surface and use the 1 , 2 and 3 hotkeys.

[sentry65]

hi, thanks again

I did not model this scene. I had to convert the whole thing into polygons because the jackass who modeled it did it in nurbs - which is fine in it's own right, but this scene is 900 or so buildings. Everything was modeled with a degree of 1 for the U direction to keep the flat look. It's so dumb because it's still tesselating each patch (side of the a building) into like 72 triangles instead of 2 that would make a simple polygon rectangle -which is all that is needed

there's some objects that are round that look round when I press the 3 key but render as a 1 degree surface. I want to keep these round and as nurbs. Advanced tesselation and rendering overrides has no effect.

I thought pressing 1-3 on the keyboard only has effect on the display and not the render tesselation? At least I've always had to go into the advanced tesselation tab to get the rendering results I want. But that tab is useless if the surface is a degree of 1 to begin with.

[joojaa]

In reply to:
still tesselating each patch (side of the a building) into like 72 triangles instead of 2 that would make a simple polygon rectangle -which is all that is needed

Set the tesselation to explicit and disable the chord height toggle and set the tesselation to 1 per span in both u and v direction. That should do the trick, quite niceley.

In reply to:
there's some objects that are round that look round when I press the 3 key but render as a 1 degree surface. I want to keep these round and as nurbs. Advanced tesselation and rendering overrides has no effect.

In reply to:
I thought pressing 1-3 on the keyboard only has effect on the display and not the render tesselation?

Wierd... Yes it only has a effect on the display (the render tesselation is differentiated on purpose so that you dont have to work with huge meshes, use atribute editor for multiple objects). But even then 1 degree surfaces should not get rounder at level 1 than on level 3, so its probably not a 1 degree surface after all.
But if the surface gets rounder then is should by all means allso render round (since its a higher order nurvbs surface), but by default atleast somewhat round (with sufficent tesselation).

[joojaa]

In reply to:
use atribute editor for multiple objects

urgh i mean the, Atribute spreadsheet, offcourse.