View Full Version : surface ID

01-20-2014, 12:02 PM

How can I get surface ID like in Kray? I have read many posts on forum but I still have trouble. Are there any video tutorials on this?


01-21-2014, 03:27 AM
Ok, now i got random colors on surface ID and object ID buffers, but they are all jaggy, they are not anti aliased. Can they be anti aliased?

01-21-2014, 04:02 AM
If camera ray hit object f.e. sphere, it didn't hit f.e. box or ground. So it has just one specific ID of object at given pixel. Otherwise buffer would be simply useless trash..

01-21-2014, 04:05 AM
so, jagged buffers do not present any troubles in postproduction? haven't really tried that :)

01-21-2014, 04:08 AM
Lets say 0 is void.
1 id is sphere.
2 id is box.

If renderer would hit box, and surrounding it pixel has void, no object, (0+2)/2 (average of values - anti-aliasing) = 1... did renderer hit sphere in that specific pixel? no.. but after applying AA, somebody would get such result looking at buffer id..

01-21-2014, 04:11 AM
You can do what I did in below video tutorial- assign objects or surfaces different colors. Colors blend together nicely. Unlike ID.

01-21-2014, 07:11 AM
hey sensei!

I find your technique very time consuming. If I had to do this every time I need buffers, I would loose it :)

I also found that DP Filter might be the way to go, but as I understand there is no way I could get anti aliased surface ID buffer with shift camera. Is that right?

01-21-2014, 11:11 AM
heh, never would have thought this is going to be so difficult :)
All I am getting are just jagged buffers. Depth buffer was easy :):):)

01-21-2014, 01:25 PM
To not have jaggies, you need a buffer called Coverage--this has the edge data needed to anti-alias the other buffer data. When I'm rendering out from Vue, for example, I save out an RPF with Coverage embedded, in addition to EXR which has almost everything else I need for compositing (Material/Object ID, Depth, Motion Vectors, etc.,) Then, in Fusion (or any composting program that can work with buffers,) I merge the Coverage with the EXR, and delete the RPF files (they're really huge, so after merging, you don't need it.)

After I have my EXR with the embedded Cover, I simply use an eyedropper tool in Fusion to select a mask based on Material and/or Object ID, and the AA is automatically applied to the selection. Easy peasey. (The process may depending on your compositing program.)

LightWave, unfortunately, doesn't allow me to embed Coverage in EXR or RPF--I'm guessing the data simply isn't available. However, all is not lost--in many situations, I simply apply a tiny bit of blur my selection mask and it works fine. This method doesn't work as perfectly as when you have Coverage but it's surprising how often I can get away with this cheap trick.

If the blurring trick fails, I just fall back on rendering an RGBA mask (using each channel as an item selection.) It's easy to set up an RGBA mask, it renders very quickly, and of course it always has perfect anti-aliasing. To make the selection in your compositing package, just set your bitmap masking tool to any one of the four channels.


01-24-2014, 05:02 AM

I thought RPF will be the solution for me, but I use Photoshop and it won't accept this file format :(

I am giving up with antialiased buffers...

01-24-2014, 05:59 AM
In DP Filter, you can get an antialiased Buffer,
whatever the source, including Surface ID,
only in the Pixel Filter node editor with the 'Multithread.AA' option,

for colorized surfaces,
connecting the Surface ID ouput of the Render Buffer node
to a Color Gradient node or the Hue of a red Color Tool node,
then connecting the result to Root Color or a Color Global Buffer,
but since Adaptive Sampling is based on the final render/beauty pass
you may have bad AA on the inner surface edges,
in this case you may need to adjust AA settings,
like higher Min Samples.


01-24-2014, 09:09 AM
I have to be the dumbest LW user ever. I can't get anti aliased surface ID buffer. Maybe someday someone will make a video tutorial, until then I will manage somehow.

01-24-2014, 09:22 AM
I have to be the dumbest LW user ever. I can't get anti aliased surface ID buffer. Maybe someday someone will make a video tutorial, until then I will manage somehow.

At least for illustrating what I said, you can look at this page,
http://lightwiki.com/wiki/Multipass_Rendering_with_Filter_Node_Editors#Mater ial_Matte_Pass,


01-24-2014, 10:58 AM
FWIW, there was a HUGE "aa'd ID buffers" a while back, with some heavy hitters contributing.

But, IIRC, the upshot was "add tiny amount of blur".