Speckley Reflections? Anyone else seen this

[MikeB]

I've been doing some expirments lately with material and reflections, this was done in VWA/RW 9.5.3b2 on a Mac G4 733. I was a little disappointed to see the black speckles on the Silver ball. Has any else seen this, is it a bug or me?

[MikeB]

I used the Conductor Shader

Ambient - 2

Diffuse - 2

Specular - 8

Mirror - 10

Roughness - 1

Refraction Red - 0.13764

Refraction Green - 0.128079

Refraction Blue - 0.156556

Absorption Red - 3.75

Absorption Green - 4.33

Absorption Blue - 2.33

The settings aren't really specific, I just kept tweeking them until it looked right.

The texture uses the Object Color which is White. There are 2 point lights. I can send you the file if you want. I've seen this with other textures too. They seem to only occur with reflective shaders.

[ 10-02-2002, 01:12 PM: Message edited by: MikeB ]

[MikeB]

The objects are spheres converted to nurbs

They show up under the final Renderworks, and custom renderworks with mapped shadows/transparency off.

[MikeB]

OK, I've messed with this some more today. It seems the "Artifacts" appear after I convert the sphere primitive into a nurb.

What I'm after here is a perfectly smooth reflective sphere. If I render the primitive sphere with a reflective texture I can see the facets, when I render the primitive converted to a nurb with out the reflective texture I get a perfectly smooth sphere, its when I apply the reflective texture to the nurb that the artifacts appear.

I haven't tried a sweep converted into a nurb yet, I'll try that next.

[MikeB]

quote:

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Originally posted by MikeB:

I haven't tried a sweep converted into a nurb yet, I'll try that next.

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That didn't work either.

[MikeB]

Here's another example.

this is a sweep converted to a nurb, with the default mirror settings. The Sphere is about 6' tall

[MikeB]

Well now I'm a little confused, this is a primitive with the same texture as the image above. But I don't see the facets that I see in wire frame.

What happens to a primitive when you render it?

[Guest]

Mike,

We know of this problem. We call em "artifacts". There are some textures that have too many lights reflecting on it and it can cause these artifacts. Let me talk to Dave and get a better answer for you.

[ 10-02-2002, 12:32 PM: Message edited by: Katie ]

[MikeB]

Was it fixed in VW 10?

Thanks

[Dave Donley]

Hello Mike:

What shaders are being used for the mirrored ball?

What render settings were used, is this Final?

I haven't been able to get the same result here with spheres or swept arcs, although I have seen these artifacts before.

[MikeB]

Alright, last one, this started as the same primitive pictured above, then I subtraced an extruded rectangle from it. the result was a subtracted solid that VW converted to a nurb in the subtraction process. While there are some artifacts in the subtracted area, there is nowhere near the distortion of the primitive that was manually converted to a nurb by me in the first image.

I hope all this is helpful to someone, I just find it kind of interesting

[Guest]

Mike,

I'm buglisting this problem. If you could be so kind as to email the file/files you are working with where this problem exists, I'd be happy.

I can add those to the buglist entry for review by the engieer.

[Dave Donley]

Hello again Mike:

It looks as if the NURBS surfaces are behaving as if they have two sides to them, and you get something similar as if you had 3D polygons that were coplanar (the "comb" effect).

I will try to fix this as soon as I can.

[MikeB]

quote:

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Originally posted by Katie:

If you could be so kind as to email the file/files you are working with where this problem exists, I'd be happy.

---

Katie:

If thats all it'll take to make you happy, you must lead a very joyous life

Whats your address?

Also, heres a summary image of what I've been doing.

And in wire frame

[ 10-03-2002, 10:58 AM: Message edited by: MikeB ]

[MikeB]

One last note,

the image above was rendered with one light,

The reflective material is simply the default mirror settings.

[MikeB]

Well, I almost let this rest but I just noticed something else

In this image the reflective nurb sphere is in front of a red primitive sphere, but you can see the red through the reflective sphere. Something dosen't seem right here.

[Guest]

I'm gonna buglist all of this together.

You can send them to tech@nemetschek.net attn: katie