PDA

View Full Version : reflection troubles.



Sarford
03-10-2009, 03:09 PM
I'm making a car paint shader (yeah I know there is one, but I wanna make my own), but I'm having some quircks with the reflections.

I hooked up a reflection node (shaders > reflection > reflections) to the reflection shading input of the surface node. Strangly, it gives me blurry reflections! But I have no reflection blurring anywhere on that material...

I have a vague feeling I'm missing something, anyone can enlight me?

rsfd
03-10-2009, 03:36 PM
Hi,
if you are rendering with GI on:
have you unchecked "Render Globals > Global Illumination > Blur Background"?

Sarford
03-10-2009, 03:52 PM
Nope, no GI used yet. If I do it the old way, through the enviroment tab, than I get a crips reflection, but I can't use that for my car shader.

rsfd
03-10-2009, 04:35 PM
Hi,
ok, I see what you mean. Quickly checked it with one of my car scenes and you are right: "classic" = sharp, nodal = blurred.

Changed Shading Mode to "Raytrace+Backdrop" and plugged the .exr as textured environment into backdrop.
That way, reflections are crisp with nodal (seems to be a bug in nodal reflection shader).

Tobian
03-10-2009, 04:43 PM
Well actually I don't actually 'see' any reflections, all I can see is the background map, which may be low resolution, hence looking 'blurry'

Put a matte object in the scene to see what kind of reflections you get? Also - try adding the HDR to the environment rather than the spherical map for the shader. I never had that kind of issue using the reflection node, but then I've never used an HDR map in that channel before! :)

Sarford
03-10-2009, 05:10 PM
@ rsfd, I think you are right, it propably is a bug. I'll try the 'backdrop' route. Thanks for your help.

@ tobian. Nah, the map is high-res enough for sharp reflections. If I use the HDR in the enviroment tab (ray+spherical) I get sharp reflections, pretty weird. Anyhow, lets see what the 'backdrop' option gives us. Thanks for thinking along.

rsfd
03-10-2009, 05:39 PM
You're welcome, glad I could help.

Seems definetely to be a bug with spherical map + nodal setup:

Now tried with a reflection sphere: setting reflection to "spherical map" gives blurred reflection with nodal setup, setting to "raytrace+sph-map" gives crisp reflections hence using raytraced reflections from the reflection sphere with the inside-mapped .exr.
Think I'm gonna fog it to NT. Thanks for drawing my attention to it!

[Btw. if you will go to use HDRIs with GI, you should check out hdrlabs.com, especially Blochi's wonderful workflow enhancer SmartIBL ( http://www.hdrlabs.com/sibl/index.html ), if you don't know it already].

toby
03-11-2009, 07:44 PM
Hi,
if you are rendering with GI on:
have you unchecked "Render Globals > Global Illumination > Blur Background"?
Please tell me they're not dumb enough to make that feature blur the reflections!!

toby
03-11-2009, 08:20 PM
I get sharp reflections with nodes. I'm on a mac too, a G5, with UB9.6. Maybe try your PPC?

Sarford
03-12-2009, 06:31 AM
Downloading right now to try it on my G5. I found that strange blurring also in the carpaint node. It didn't matter if I used a HDR or not. Using backdrop gives clear reflections.

Sarford
03-12-2009, 07:05 AM
I just tested it and both versions give the same result. This is a bit strange... I'll try with a different HDR although it would seem odd if that would be the problem.

Here are screen shots of the renders on both machines (same scene, same settings)

Sarford
03-12-2009, 07:09 AM
Nope, a different HRD gives the same blurry result. Only tested on my mac pro this time. The used HDR is from Dosch Design.

Tobian
03-12-2009, 07:15 AM
I wonder if it's the HDR format. I noticed toby used an .exr format?

Sarford
03-12-2009, 08:24 AM
Now with a EXR, still the same blurryness...

Tobian
03-12-2009, 08:39 AM
It shouldn't make a difference, but could it be because you set the samples to 1? I usually do that to speed it up, but I don't put in reflection maps...?

Sarford
03-12-2009, 09:15 AM
Well, it shouldn't. Since it only uses a reflectionmap and needs no actual raytracing, one sample should do it. But I did try more samples, it didn't make a difference though.
I'm realy stumped by this problem...

Tobian
03-12-2009, 09:29 AM
Well just use the BG then, looks like an anomalous bug! :)

toby
03-12-2009, 03:22 PM
Only difference now is that you're on OS10.5...

rsfd
03-16-2009, 04:01 AM
Hello to all,

finally had time to check with UB9.6 on my G5 and 10.4.11.
Everything works as it should - so it's UB9.6 with Leopard.

toby
03-16-2009, 04:20 AM
so it's UB9.6 with Leopard.
That's an idea, Sarford did you try it in CFM?