Medallion

SATtva_ · Post by **SATtva_** » Tue Feb 03, 2009 1:59 am

I'm done. %)
http://www.indigorenderer.com/joomla/fo ... php?t=5358

Not fully satisfied with the look of scratches, but it's the best I can do. ^^"

Kram1032 · Post by **Kram1032** » Tue Feb 03, 2009 7:07 am

It improved a lot

In the original, ther is some chromatic aberation and the reflections are sharper... I guess, your basic exponent is still too low and your edges aren't fully correct here... (slightly different edgeshapes can result is extremely changed reflections.... though, so does both camera angle and the light source's position.... at least one of the three is wrong here.)

Overally, it's very close

well done!

SATtva_ · Post by **SATtva_** » Tue Feb 03, 2009 7:33 am

Thanks Kram.

Yeah, I know it's not 100% accurate representation, but that wasn't my goal (it's better to make "good enough" than to never make "perfect").

Kram1032 · Post by **Kram1032** » Tue Feb 03, 2009 8:15 am

yeah, true

dmn · Post by **dmn** » Tue Feb 03, 2009 4:11 pm

I saw this cg paper somewhere that talked about how scratches in a malleable material like metal are actually more of an M than a V. The act of scratching the surface actually pushes material up on either side of the valley. Taking that into account in the scratch map gives more light reflection when the light source is coming from behind the camera.

Kram1032 · Post by **Kram1032** » Thu Feb 05, 2009 5:24 am

faking such scratches would need an extremely high-res bumpmap... or some kind of special "scratch shader", which might consist of two images, one being a "highres" slice-shot of a scratch (could also be colourcoded more than one - at least 3 for RGB, maybe even 4 with unusual usement of A - RGBA^^) and the second, a bw (single scratchtype) or colour-map (multiple scratch types) with some strokes, where, let's say, the brightness represents depht, the line-width the scratch width (would need some subpixel-AA-recognition) and the shape (d'uh) the position of a scratch...
+ a nice overlaping scratch detector...
+ ...
O.o

ok, I guess, either a super highres bumpmap or a super smart shader with ISL....

SATtva_ · Post by **SATtva_** » Thu Feb 05, 2009 5:39 am

I vote for the shader. ^^ I used 8192x8192 for the medallion -- it's royal pain to even just edit such image in Gimp. Maybe vectored image in Inkscape could produce better results (for the mentioned M-shape and narrowing of scratches on their ends), but I was already exhausted to even try this.

Kram1032 · Post by **Kram1032** » Thu Feb 05, 2009 8:50 am

(2^13)² px O.o not bad!