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View Full Version : how to render out only Z Buffer?


Byla
12-16-2005, 07:55 AM
Hi everyone.

Trying to render out only the Depth image sequence on a very complex scene, but every time I am trying to figure out how to render out ONLY Depth and nothing else, I just cant. I select multipass rendering, add only depth, save that as a multipass image (with only Depth on), but it still renders the image (normal, RGB) and it takes a lot, A LOT of time to do that.

Any suggestions how to get only the passes selected without the RGB image itself?

moka.studio
12-16-2005, 09:10 AM
Hi everyone.

Trying to render out only the Depth image sequence on a very complex scene, but every time I am trying to figure out how to render out ONLY Depth and nothing else, I just cant. I select multipass rendering, add only depth, save that as a multipass image (with only Depth on), but it still renders the image (normal, RGB) and it takes a lot, A LOT of time to do that.

Any suggestions how to get only the passes selected without the RGB image itself?

using Multipass image doe not work if you select .tif as the output type.
You need to use Photoshop as the putput type.
The depth will be outputed as an alpha channel. works fine here
Otherwise, to output as tiffs, the disable the Multipass option.

Also, make sure you turn off a lights+ reflection and other effects from the materials, as these will only eat up render time.

Byla
12-16-2005, 09:15 AM
so what you are saying is that there is no way Cinema can only calculate Z buffer and export only that? That is quite crazy to be honest.

because if I do as you said I should, I still get image calculation.

moka.studio
12-16-2005, 09:22 AM
so what you are saying is that there is no way Cinema can only calculate Z buffer and export only that? That is quite crazy to be honest.

because if I do as you said I should, I still get image calculation.

ok, I see what you mean.
Yes the image is still being calculated, and the Depth is being processed after that.
Would be nice if you could just get a depth output.
Have a look at Zblur from www.3dAttack.net,
maybe there is a way for it output purely the Z buffer....
If so, it may be a worthwhile investment for you.

Otherwise, as I said, bake everything in the scene, turn off all lights+materials etc.. to try to make the render time as short as possible.

And send a suggestion to Maxon, this would be a good option to have

christianS
12-16-2005, 11:27 AM
Hey Byla

I see that it would be nice to hae an inbuilt function for that.

But there is still a shader-solution for that.
You could delete all materials and add a material for displaying z-buffer. Use Gradient in luminance-channel, set type to spherical and space to camera.

Another solution would be to use Fog

Byla
12-16-2005, 11:50 AM
I already have the Z buffer set, so I dont need shader solution for that, But I guess deleting the assigned materials and replacing them with simple ones would give me the result needed: fast rendering.

tcastudios
12-16-2005, 12:45 PM
Eh, I have to ask. I used to render to RLA and use the Zbuffer within.
Now trying it, I don't get a Z-buffer out of Cinema in the RLA file....
I have to admit it was a long time ago i did this (like in R8.5 if my memory serves me right)but I don't remember doing anything special to make it work,( other than checking the Zbuffer in the RLA render options)

Does anybody get their Zbuffer out of Cinema in a RLA file and then using it for Lenscare in AE? Hopefully I'm just missing something trivial.

Cheers
Lennart

tcastudios
12-16-2005, 01:00 PM
Otherwise. Using MultiPass and check Depth, setting the Camera Back blur to 0 > (whatever)focus to 0, as well as uncheck Regular Save -and- turn all lights of (incl autolight) it is only the Depth that is calculated/rendered. This way no materials have to be swapped.


Cheers
Lennart

paulselhi
12-16-2005, 01:03 PM
have a look at c4dcafe.com 3dcrew did a good tut on this using a depth map for a pin head animation

Tank_3D_Attack
12-16-2005, 02:30 PM
Easy task with zBlur actually. All you have to do is activate "Post Effects" in the Multi-Pass option and that's it. Only thing that will be rendered is the depth channel and that's it. See screenshot.

Thomas

Byla
12-16-2005, 02:54 PM
Aha hmmm... so, with zBlur on, there is no image rendering, just z deph? I mean, with proper settings of course?

Tank_3D_Attack
12-16-2005, 03:04 PM
Aha hmmm... so, with zBlur on, there is no image rendering, just z deph? I mean, with proper settings of course?


If all you want is the depth then you activate "Post effects" and it will output the depth for ya. This is if you only want the depth of course. Usually zBlur renders the whole image with blur using it's own zbuffer or C4D's buffer.

AdamT
12-16-2005, 03:11 PM
Sounds like ZBlur is the way to go, but if you don't have it you could use Majoul's free "Global On/Off Texture" to turn off all textures and global brightness (render settings>options) to turn off all lights. Should be pretty quick then.

Byla
12-16-2005, 03:12 PM
someday I have to go through this Zblur and see what the fuss is all about and why would it be a better solution compared to the blur I do with Shake or Lensflare plugin...

lightdog
12-16-2005, 07:28 PM
To render out only the depth pass of a render, I use this method:

1. Make sure that "Save Image" is Unchecked in the "Save" panel.
2. Remove all post effects.
3. Enable only the Depth Channel in the Multi-Pass panel and enable the save option from here, instead of the "Save" panel.

No image is saved, only the depth channel.

AdamT
12-16-2005, 08:17 PM
The image is still calculated even if you disable "save image" in the render>save dialogue.

TimC
12-16-2005, 08:32 PM
Sounds like ZBlur is the way to go, but if you don't have it you could use Majoul's free "Global On/Off Texture" to turn off all textures and global brightness (render settings>options) to turn off all lights. Should be pretty quick then.

Just be careful switching off all materials. If you've used displacement for example then the Z buffer will be incorrect.

cheers
Tim

lightdog
12-16-2005, 08:46 PM
The image is still calculated even if you disable "save image" in the render>save dialogue.

A render test confirms that turning off "auto light" (and other lights) does not disable image calculation. All it does is render "black", but the render time is still slower. So even though the picture viewer does not show an image (showing only an image in the depth channel), the render time appears to be the same as if "auto light" was enabled, indicating that image calculations are enabled.

I've been running extensive low-resolution animatics with multi-pass renderings (in some cases with image disabled and only the depth pass enabled) so this issue was not immediately apparent.

AdamT
12-17-2005, 01:59 AM
True there's some calculation going on, but I just did this quick test with a 3-point light rig, area shadows enabled for all 3 lights. Normal settings, 52 seconds. Global brightness to 0%, 8 seconds.

mustardseed
12-17-2005, 02:07 AM
So the verdict is that there's no built-in(ie: automatic) way to render out specific individual passes from C4d? That's surprising. Even with apps like ElectricImage it's as simple as checking a box in the render dialog. I thought Cinema's multipass rendering system was more robust than that?

AdamT
12-17-2005, 02:10 AM
So the verdict is that there's no built-in(ie: automatic) way to render out specific individual passes from C4d? That's surprising. Even with apps like ElectricImage it's as simple as checking a box in the render dialog. I thought Cinema's multipass rendering system was more robust than that?
Yep, it's unfortunate but true.

lightdog
12-17-2005, 02:21 AM
True there's some calculation going on, but I just did this quick test with a 3-point light rig, area shadows enabled for all 3 lights. Normal settings, 52 seconds. Global brightness to 0%, 8 seconds.

Interesting. Did both tests generate the same depth pass? I would assume so? (I'll explore more this weekend).

Your test seems to indicate that the best way to have C4d quickly generate only the depth channel is to turn off all lights and/or set light values to zero (including "auto light"). Although there is some proc time spent calculating an "image," this "image" is neither visible not saved (with "save image" disabled), and per your calculations, takes up minimal render time to process.

Byla
12-17-2005, 09:49 AM
Yep, it's unfortunate but true.


jep, suprised here as well. No sure whats the case, I do agree that most of the time you would need RGB image as well and that is needed I guess for most of the multipass layers, but surely not for Z depth. You could even get that out of your graphics card chip.

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