Author Topic: Dull Looking Metals  (Read 12509 times)

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Offline Jayceyned

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Dull Looking Metals
« on: May 17, 2011, 09:04:01 am »
Hi,

I'm working on a bunch on domestic appliances, and will be for the for-seeable future, and sometimes struggle to get really rich, deep and highlighted  metals.

As domestic appliances, there are a lot of large flat surfaces, and I am wondering if Keyshot is not great at rendering this geometry; or if more likely, it's me.

I particularly struggle when trying to show the gloss of a brushed stainless steel / al. surface,  without getting blown out highlight or jet black shadows.
I end up swapping out environments time after time looking for something with a nice amount of ambient light, as well as some crisp lines for highlights. I also try increasing the roughness of the metal to give me more evenly dispersed lighting (avoiding blown out areas), but then the material ends up looking so matt, that it almost looks as if it's a sheet of printed paper.

If anyone has any tips or tricks of how to best render out large flat areas of brushed metal, using dramatic lighting I'd really appreciate them.

Many thanks in anticipation,

Jay.
« Last Edit: May 17, 2011, 09:07:31 am by Jayceyned »

Offline Ed

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Re: Dull Looking Metals
« Reply #1 on: May 17, 2011, 10:22:36 am »
Jay -

For a large flat area of brushed metal I would use a custom texture map and a bump map.  Not the texture map that is supplied with the regular Brushed Stainless material, but one you create.

Basically your surface material needs some built-in highlights and darker areas to create that look.  It sounds like the HDRs you're trying have soft, flat lighting, so your surface looks flat, uniform and dull.  Also, if there are no other objects in the scene to reflect off the surface, it will look flat.

To make a square texture map in Photoshop, search the web for one of many "Brushed Metal" tutorials.  Then, you'll need to overlay that in PS with an alternating black, gray and white gradient to create the highlights and darker areas.  For the bump map, use the one for stainless steel that comes with KeyShot.  Adjust the size of the texture map and bump map independently for desired affect.

If you want to do a real quick test, find a photo of a large, flat stainless surface, and crop out a square section.  Use it as the texture map in the stainless material.  Set to no-repeat and adjust size as needed.

With this technique you can get the "stainless refrigerator door" look with just about any HDR.

You can also use HDR Light Studio to create an HDR with dark areas as well as "hot" areas to liven up the surface.  I used this technique for the attached titanium ring with brushed finish.

Ed
« Last Edit: May 17, 2011, 10:42:38 am by Ed »

Offline Jayceyned

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Re: Dull Looking Metals
« Reply #2 on: May 18, 2011, 01:26:05 am »
Thanks Ed,

have just tried creating a texture but I think your second approach may prove better for me.

I really appreciate your help on this.

Any chance you maybe able to send me a screen grab of what the environment HDR looks like that you used for render of the ring?

Offline Ed

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Re: Dull Looking Metals
« Reply #3 on: May 18, 2011, 11:27:12 am »
Jay - I did a fast test by sampling a small square from a stainless cooking pot photo on the web (upper left corner).  I applied it to the brushed steel material, and used a brushed metal normal map from the KeyShot library.  The HDR is called "Kitchen" and you probably have it in your library.

There is some "banding" due to the small size and poor resolution of my texture & normal maps, but the overall result is very close to how my stainless refrigerator door looks.  With a larger, higher resolution image map, the result would be much better - but this illustrates the potential. 

You could also make a stainless steel texture map like this using Photoshop gradients (hint: don't use strictly black & white - tint with a touch of color for realism).  This allows you to make a high resolution map, and you can also try distorting the map by adding a slight curvature.

Unfortunately I can share my ring HDR at the moment due to an agreement, but the environment contains a couple of very dark stripes with soft edges that show up in the ring as dark bands.  Without that, the metal would look very flat.  You can also experiment with placing dark objects in the scene (out of camera range) to reflect on the metal.  As with photography, you're not really taking a photo of the shinny object, but rather what it reflects.  If the environment is evenly illuminated (flat lighting) then the metal will look flat and dull.

Post some of your work and I'm sure you'll get some good feedback.

« Last Edit: May 18, 2011, 11:39:43 am by Ed »

Offline Ed

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Re: Dull Looking Metals
« Reply #4 on: May 18, 2011, 02:18:02 pm »
Here's another example.  Same texture map and HDR as the post below.  However this time I enlarged my texture image to 400x400 px in Photoshop and added 2px of Gaussian blur.  This gave me a cleaner, higher resolution image for my material.
« Last Edit: May 18, 2011, 06:07:23 pm by Ed »

Offline Jayceyned

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Re: Dull Looking Metals
« Reply #5 on: May 19, 2011, 01:23:01 am »
Thanks again Ed,

really helpful and I really appreciate it.

Unfortunately I'm not able to post the renders = they're concepts for the company that I work at and am sure I'd get n big trouble, but I will try and replicate on something similar if I get a chance here.

Thanks again for your help, I really appreciate it.

Take Care,

Jay.

Offline justindustrial

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Re: Dull Looking Metals
« Reply #6 on: May 20, 2011, 05:35:43 am »
if you're looking for highlights in certain areas and nice reflections you could try adding a few emissive spheres / planes to your scene and using them as accent lighting. There is a good webinar out there on adding lights to your scenes. They increase rendering time significantly, but do make a really nice difference.