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View Full Version : render speed ? Can I make it faster ?


Tripdragon
02-26-2005, 04:20 AM
I have cinema 9 demo on this G5 powermac, but I dont think Cinema is using even a thrid of it's power. The renders are monster-sly slow.. Even if I have radiocity and raytraceing off. I mean if luckly the basic render of a box with no shader on takes .7 seconds... So if I fillet it to make some more mesh it gets down to 1 sec,, and more mesh makes even slower, Radiocity and or raytrace jumps to 10 minutes :(

I have seen much faster even in blender

Hilt
02-26-2005, 04:51 AM
Can you post a testscene or screencapture with info of rendertime of what you're rendering?
Would be easier to know if there was something with your system, or are you just in rush.

.hilt

AdamT
02-26-2005, 05:15 AM
Um, are you serious? You're complaining about sub-one-second renders? Sub-ten-minute GI renders? Probably that blazing-fast Blender is the right choice for you!

On a serious note, there's no way to tell if you have a problem or what the problem might be without more info.

Tripdragon
02-26-2005, 05:45 AM
Well of course the blender render is not to hot, but abasic transparentcy is faster with a high poly count.

powermac dual 1.8 g5 1.2 gig ram 5200 CG card.

A question then could be is it the demo edtion that has a slower speed... and or, does the render view take into account a backface cull for a non transparent shader ???

Per-Anders
02-26-2005, 06:05 AM
the demo has the same render engine as the full app.

c4d does not backface cull at rendertime (this would make no sense to do as shadows, displacement, reflections on other objects and any number of other effects would not be possible if it did, no render engine backface culls at rendertime). if you want backface culling in viewport simply switch it on.

as for speed comparing simple transparency scenes with high poly counts, try reducing your ray depth in the render settings. additionally to compare blenders default with cinema switch off antialiasing in cinema, and make sure to not use the fresnel option in the transparency. also try using exactly the same scene in both. and use the application that suits you best.

Tripdragon
02-26-2005, 07:15 PM
hmm that seems to have increased the speed. I also found a pref that uses 8 lines of render and that has made it faster to me at least .. Thank you.. This app has so much new stuff to me it is sweet

duderender
03-02-2005, 03:06 AM
the demo has the same render engine as the full app.

c4d does not backface cull at rendertime (this would make no sense to do as shadows, displacement, reflections on other objects and any number of other effects would not be possible if it did, no render engine backface culls at rendertime). if you want backface culling in viewport simply switch it on.

as for speed comparing simple transparency scenes with high poly counts, try reducing your ray depth in the render settings. additionally to compare blenders default with cinema switch off antialiasing in cinema, and make sure to not use the fresnel option in the transparency. also try using exactly the same scene in both. and use the application that suits you best.

I thought that was whole purpose of normals? To tell the renderer what receives lights. For example if you model a box, flip the normals to point towards its center and render you should see only those faces with normals point towards the cameras.

However I found in C4D that this is not the case, as it will treat all faces as having normals (i.e. doublesided). Perhaps a bit early to reply, but I am just now finding this out and experimenting in C4D.

Ernest Burden
03-02-2005, 01:28 PM
if you model a box, flip the normals to point towards its center and render you should see only those faces with normals point towards the cameras.

However I found in C4D that this is not the case

In Lightscape any backfacing polys rendered black. That really sucked, especially since you would have to start over on the radiosity if you wanted to fix them.

So Cinema seems to be more tollerent of normal facings. And there is an interesting feature in Cinema, where you can assign different materials to the front and back face. So if you really want backfacing polys to not show, assign a transparent material to all backfaces. Then they will not render.

duderender
03-02-2005, 04:13 PM
In Lightscape any backfacing polys rendered black. That really sucked, especially since you would have to start over on the radiosity if you wanted to fix them.

So Cinema seems to be more tollerent of normal facings. And there is an interesting feature in Cinema, where you can assign different materials to the front and back face. So if you really want backfacing polys to not show, assign a transparent material to all backfaces. Then they will not render.

Are you sure they won't render (I mean as far as adding render time to render them transparent)? I find it odd that it's even a feature to render "rear" facing polys by default and to not have an option to turn them off? Way back in graphics programming part of the teaching was to scan for rear facing polys and remove them from the render queue.

Odd. I agree that assigning materials to the rear facing polys is cool... a different approach from say LW which makes you dupe the polys and flip them.

duderender
10-26-2005, 06:26 AM
I've been revisiting this issue. Also re-reading Jeremy's book on lighting, where in he talks about applications allowing you to set culling to faces so that you can get full reflections.

For example, a box room where the camera is outside the room and a reflective sphere within the room. This way if you could render from outside the room you would have all walls of the room reflecting on the sphere.

If you could not do this, you may not get the correct camera focal/FOV because of the room dimensions.

Is setting the backfaces 100% transparent the only way to do this?

Per-Anders
10-26-2005, 07:08 AM
yes, or in that situation just use a compositing tag on the room and switch off seen by camera if you don't want the room to show at all, or instead simply modify the cameras "Near Clipping" distance. to clip out anything in front of the camera for however far you want.

duderender
10-26-2005, 07:19 AM
yes, or in that situation just use a compositing tag on the room and switch off seen by camera if you don't want the room to show at all, or instead simply modify the cameras "Near Clipping" distance. to clip out anything in front of the camera for however far you want.

Thanks. It would be neat to add the option to a selection rather than only the object being seen by camera.

Vozzz
10-27-2005, 04:00 AM
ohohohoooooh *jumps up and down in excitement* I think i know the problem!

You have a mac :D ;)


hehe.

But seriously if you want to find out, you should post a scene here witht eh render time and then someone with similar spec can see how long it takes them to render.

Primitiv
10-28-2005, 12:33 AM
Why don't you stick with Blender then?

Rendering speeds are directly related to your working habits.

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