Problem with Animated Brushed Metals

#1

Im doing a product animation and still for a client, in which I’m using different metal shaders. One of the most prominent and used shaders I’m using has a brushed metal look to it. For my stills the shader looks great but once I animate the object or camera i run into a HUGE problem. It looks as if the brushed metal strokes are not moving with the object itself. As if it were an overlay of some sort I put on in post, they just sit still on top of the object and its very visible in the highlights and reflection areas of the object. I am unsure if its in the shader or possibly in my lighting setup? It looks amazing for the still product shots but 100% unacceptable for the animation. Any help would be greatly appreciated.

-Ben :banghead:

#2

What DCC are you using?

If you’re in Maya, you probably have a 3d texture node sitting somewhere in your scene. If the object is not deforming, then you can just parent that node to the object and hey-presto, the texture will stop “swimming”. If your object IS deforming, you’ll need to bake the texture into a UV-based texture map to use.

#3

Hi Ed I am indeed in maya. Here is a picture of what one of my shaders looks like that is having the problem. There is no 3d Texture node in the scene, that I could find in the outliner or hyper shade. Hopefully you will be able to help me out thanks for the advice in the first place it made sense that that would be the problem until i found no 3d texture node >.<

#4

huh, just a file texture?

huh.

hrm.

Try deleting construction history on the object. If you used any UV projection techniques, the nodes associated with their creation may still be applied. So whenever your object moves, the UVs would be swimming as well.

#5

arrghh still no solution. I deleted the history and the brush strokes stayed. The annoying part is the metal texture with some strokes im using in the diffuse is moving fine… its just the highlights and such caused by the anisotropy that are staying put…

#6

ohhhhhhhhhhhhh

Okay – reflections 101. You may already know all this, but for the benefit of whoever else might read this thread, here it is.

There are two types of lighting you can apply to a material in CG – light that is reflected specularly, or reflected diffusely. Diffuse reflections look the same no matter what angle you look at them from, because the light is scattered evenly in all directions. Usually these reflections are just called “color”. The specular reflections (either faked highlights or “true” raytraced reflections) are view-dependent, meaning they reflect based on angle of incidence. If you pick up a mirror, hold it perpendicular to the ground, and move it up and down, the reflections won’t move but the mirror will. It almost looks like a window.

I’m guessing in your case that your objects are moving, but your lights or reflection cards are not. If you really want your specular reflections (the anisotropic highlights) to “follow” the object through space, then you need to literally make the lights or reflector cards follow the object through space.

I hope I haven’t insulted you with this really basic explanation, I teach lighting to freshmen, so I’m used to simplifying a lot.

EDIT: Looking back at the thread again, I’m pretty sure this wasn’t what you were looking for – it’s probably a different problem. Still, it’s a good lesson :smiley:

#7

Hey Ed, thanks for the 101 lesson :slight_smile: I am familiar with the things you stated but no worries I dont at all take it as an insult Im glad you are so willing to help! This is truly starting to really really frusterate me though… I will give it one more day of trouble shooting tomorrow and if I come up with a fix ill be sure to post it. There is no way im going to animate the lights that just doesnt seem like a practical way to do it although it may be a fix since I’m in a pinch! But animated lights= no final gather map :frowning: = insane render times. Thanks again

#8

You could also bake out ALL the light and reflection on your objects, but I’m not entirely sure how well that would work.

Or, you could try adding a tiny amount of procedural bump to the objects to give them a very very subtle warping to the surface. Then, when your camera moves, the reflections/highlights won’t “stay still”, they’ll move across the warped surface in a more convincing way.

#9

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