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Hi Guys- I don't know if this has ever been asked for.. and it may be something that is possible now ( I am still on 1.7 for a couple more weeks). When you look at some scratched metals i.e. an older stainless steel pan that you may use in your kitchen you often see circular swirls that center on your viewpoint and move with the light reflections and your point of view. I think that it derives from VERY VERY small scratches and because the scratches are so random and so numerous that light reflects off of similar angles and gives you this circular effect. I am not speaking about simple brushed metal surfaces but rather the random scratches that metal receives in day to day use.

I am probably not doing this justice in my description ... I have tried searching for images to illustrate my point but can't find any and my camera is broken .

I have never seen a photo of this effect but have seen it in the real world every day. I think that a lot of the jewellery renders would benefit from MICRO scratches that pick up the light very subtly. I have added scratches to my metal surfaces but they seem to either be non existent or too pronounced.


Any thoughts

Yes, it's possible with bumps.

Photo Reference


http://resources.maxwellrender.com/sear ... v2=0&tipo=


http://resources.maxwellrender.com/sear ... v2=0&tipo=


http://resources.maxwellrender.com/sear ... v2=0&tipo=

I agree and i think we have wished for this for a few years now. It's called anisotropic scratfches

This example is done in Vray


/ Max

Thanks Tom and Magnus... I am sorry to be a pain ... but neither of those is exactly what I mean.

Tom... those are close but the scratches still seem pretty large, well larger than the sample photo which is pretty close to the look I am trying to achieve. The thing about the reference photo is that the scratches don't seem deep or bumped out but in the simball renders (and the ones I have done) it seems that to achieve that look you have to have bumped out scratches which at least for jewellery don't always do the whole trick. Here are the two types of scratches that I see all the time (I am a goldsmith as well)

1) Deep scratches usually directional caused by polishing wheels, sanding wheels etc. In the trade we often call them drag lines.
2) Lighter scratches overlaid with the deeper scratches caused by grit in fingertips, contamination of grits during polishing, or in the case of jewellery actually worn contact with grits, clothing etc.

So the problem that I have with my metals is how to achieve a slightly scratched yet still perfect enough to buy look. I think that the combination of these simball renders with larger bumps... smaller scratches are needed for jewellery... would be great if combined with some smaller light catching scratches like the reference photo.

Not trying to be a stick in the mud I have been trying this for a while and I have come close but am still not 100% happy with the results.
Here is a photo of a white gold that I created with a VERY soft bump/scratch pattern

I think it has very much to do with the quality of the scratchy texture map that you use. The finer the scratches, the higher res texture you will need.

Thanks Brian... I will have to start making my own textures I think . I have some good ones that Magnus posted which I use for my brushed finishes but I think that I am going to have to start working on some of my own for the smaller micro scratches.

Thanks again guys... I will wait until I upgrade to start fooling with this further
Cary

I have one rendering at home right now. When I get off work, I will stop it and post it if it's any good. I made a 6kx6k scratch map from a cgtexture.com map. We'll see if it works.

Hey Bubbaloo- I was planning on making my own scratch map by hand, old fashioned style on a piece of paper with some pencils. I am not the best at photo editing... apart from the basic stuff..... do you think that this will work?

It could very well work if you have a high res scanner. But I would think it would be so much easier to find a good photo texture. I dunno. Do whatever you are comfortable with.

Thanks Bubb... always wanted to say that, along with ..... 'why I oughta...' I have been listening to a lot of old time radio shows lately so please excuse the ancient vernacular

I do have a fairly high res scanner but maybe not 6k x 6k. I have a Canoscan LiDE 600F which according to Google has a resolution of 4800 dpi x 9600 dpi vertical. So hopefully that will get me into the ballpark .

Well, here's my first test. I'm not satisfied with it yet. Needs a better map I think.

I think such a finish will ideally require procedural scratches and I transform this wish into that in my mind.

tom wrote:I think such a finish will ideally require procedural scratches

Well when is that going to happen, Tom? Huh? Huh? Huh? When?

tom wrote:I transform this with into that in my mind.

Say what?

tom wrote:I transform this with into that in my mind.

Me think he speak in fourth tongue!

Tom... what are procedural scratches?