Rendering flat stainless steel

[Drachen]

I wanted to ask if anyone has ever developed methods for rendering FLAT stainless steel?

I've been doing product renders for several years for a client. They manufacture stainless steel kitchen equipment, and I inherited alot of assets from someone they used to have on staff, and it was all in Mental Ray. I continued to develop the MR renders to a higher quality level, but I've recently decided to switch to Vray because I know I can develop them much further. I've been using Vray off and on since the 1.47.xx days and recently upgraded from 2.4 to 3. I have a test scene that has a vray dome light with an HDRI of a studio lighting setup. The spheres on the left have the exact same materials as the table on the right. As you can see the flat surfaces on the table just don't read like the curved surfaces of the spheres. I struggled alot with this in Mental Ray as well, and wanted to see if anyone else had encountered this and/or developed a solution?

Thanks very much in advance.

[rjohnson33]

You might benefit from introducing some variation into those flat surfaces to break up the uniformity of the reflection.
Nothing too extreme but you could use a subtle bump map or adjust the geometry itself with a noise modifier.

A subtle variation in your reflection/reflection glossiness in the material itself (something like a grunge map with fingerprints/scratches) would also help to break that blandness.

[Alan Iglesias]

Your stainless steel looks a bit flat because there are no interesting reflections, and also there are no diffuse element that I can see in the material.

In a case where you are trying to create interesting looking reflections in a scene where there is nothing really to reflect, I sometimes use a nice monochromatic HDRI so the pieces have something to reflect. A goodly amount of blur (glossiness) in the material and no one's the wiser.

In a scene using an HDRI for lighting, I would put a physical piece of geometry (like a sphere mapped with a B&W picture of the contents of a room or for instance) around the pieces and set it to cast no shadows and only render in reflections.

Also, stainless steel often has some level of texture that shows itself in the diffuse element of the surface, so a little texture and bump mapping with the appropriate masking elements (reflecftion and specular maps) can also add hightened realism.

Hope this helps some,

-Alan

[Drachen]

There is a noise map in the reflection and bump slots to produce the grain in stainless steel, it is also hard to get it to read on the flat surfaces without upping the map size. By the time it becomes visible, its no longer realistic looking. Have been playing with different methods of distorting the reflection, need to stick with a material tho. Tried physically warping the geometry a while back and the client nearly had a heart attack. Same goes for fingerprints/scratches.

Thanks, I will keep at it!

[eyepiz]

I wanted to ask if anyone has ever developed methods for rendering FLAT stainless steel?

I've been doing product renders for several years for a client. They manufacture stainless steel kitchen equipment, and I inherited alot of assets from someone they used to have on staff, and it was all in Mental Ray. I continued to develop the MR renders to a higher quality level, but I've recently decided to switch to Vray because I know I can develop them much further. I've been using Vray off and on since the 1.47.xx days and recently upgraded from 2.4 to 3. I have a test scene that has a vray dome light with an HDRI of a studio lighting setup. The spheres on the left have the exact same materials as the table on the right. As you can see the flat surfaces on the table just don't read like the curved surfaces of the spheres. I struggled alot with this in Mental Ray as well, and wanted to see if anyone else had encountered this and/or developed a solution?

Thanks very much in advance.

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I have always struggled with flat surfaces, try using the MiaFalloff in the reflection slot.

[Drachen]

Your stainless steel looks a bit flat because there are no interesting reflections, and also there are no diffuse element that I can see in the material.

Alan, I should clarify. The scene on the left with the spheres was also created by me. The table on the left is in the same max file, just on a different layer. So table os rendered with the same materials, lighting and camera angle ad the spheres by just toggling one layer off and another on. The table has no interesting reflections because it is flat, not because there is nothing to reflect. The spheres render with beautiful reflections of the softbox and umbrella lights visible in the HDRI.

Admittedly the noise map I have that created the grain visible on the spheres is not showing up on the table. The spheres are using their own native mapping coords and the table has a box map on it and i haven't quite tweaked the size to be visible. But when turning the spheres off and the table on the reflections just dont show up.

I agree that increasing the visible grain in the material will help, but this is not an issue of there being nothing to reflect.

Both the spheres and the table are rendered with a Vray dome light using an HDRI map of a studio lighting rig.

[Alan Iglesias]

The spheres render with beautiful reflections of the softbox and umbrella lights visible in the HDRI.

You are actually getting the exact same reflections in your table - just a lot fewer of them because it is flat and is not sampling (reflecting) anywhere near as much of the surrounding area as the spheres are.

That's why in cases like this I add "extra" stuff for the flat surfaces to reflect, even if the "stuff" is not in the scene itself. Because they are typically quite blurry they usually look great.

It's the same idea in which when you see a shiny logo on a white or black background but it seems to be reflecting so much stuff that isn't actually there. In the (very) old days we did that with non-raytraced reflection mappng. These days I use raytracing and GI like everyone else, but I also use the tricks I learned way-back-when to make things look good when needed.

Feel free to send me the file and I'll show you what I mean...

-Alan

[fraggle]

In reality, nothing is flat in a metal furniture. Making a box geometry will give you a flat reflection.
sheet of metal bend at 90° and welded in its corner = can't be flat. Go to a restaurant and have a look to their stainless steel equipment. Bring a ruler with you and check the planarity at the edges, you will be very surprise how bumpy it is.
More than 1M long = can't be flat, there should be tension in the metal sheet, mostly going down.

Such default can be mimic but takes really long to achieve because the need extra mapping UV map or even extra modelling (depending on quality level you are looking for)

[soulburn3d]

This tutorial may help explain:

http://www.neilblevins.com/cg_educat...c_surfaces.htm

- Neil

[kalamazandy]

Neil got is spot on. You can't manufacture a flat SS panel and make it anywhere near affordable. If you want to get really good, paint your own bump maps. You don't have to Curve your geometry. Just make it look like it. If metal gets bent down at the edge of a table like that, it will probably bulge up slightly, maybe not enough to see in the geometry, but enough to bend the light. So add a bump map reflecting that. Did someone punch a couple holes in it to add a handle, which is then screwed to it from the back? That's going to bend the metal as well. The hole will probably bend the metal down. And the handle being attached will deform the metal between the two holes a bit.

Also do some experiments. Your HDRI is actually no good for flat objects. Do some experiments with some flat metal objects. The bigger the better. Take a few pictures. Try out a couple umbrella lights, and then try out a few pin lights (led will work fine). The pin lights will give you much more predictable results.

One last thing. You will Never make all your clients happy. One person will like it, another will hate it. There seems to be a consensus that you Have to be able to see grain, no matter what distance you are from the object. Look at the images online of appliances. A good portion of them are 90% photoshop. I'm not even sure why they take pictures. The photographer takes a few images, merges them together, then take any flat areas of the stainless and lay over a stainless steel pattern to match the grain direction and scale it just large enough to see it. Then they paint on a nice even gradient because that's what everyone thinks of when they see stainless steel. If it's a curved door, then they just put all the highlight in the center. Of course, if the grain is vertical that's not even correct, but they don't care. That's what they do anyway. I once took a picture of a unit and showed that to the client, and they said it didn't look real enough, and that the stainless needed some work. I did the whole thing in photoshop and they liked it. :/

If it's for a still image, realistic stainless is generally most efficient to do mostly with photoshop. If your animating, you can get away with making adding some bump maps at the points the metal has tension, like Neil suggests. Don't forget that unless you're using realistic caustics or something like that, you'll want to create a material override, and lose the grain for what GI looks at. You'll save at least 20% or so in GI calculations and you'd never know the difference. I generally place that in the reflection slot as well.

[Drachen]

Thanks everyone for weighing in, I really appreciate the feedback.

These days I use raytracing and GI like everyone else, but I also use the tricks I learned way-back-when to make things look good when needed. Feel free to send me the file and I'll show you what I mean... -Alan

Alan - thank you, will probably take you up on that offer. Sorry I have not replied for awhile, I've been working on a bunch of wall graphics for my clients upcoming convention.

This tutorial may help explain: - Neil

Neil - I've actually had 3 or 4 friends send me your tutorial already, but thank you!

Kalamazandy - my clients are for the most part very happy with what I generate, and in my Mental Ray renders I was not above using a photo metric light and the Align highlight tool to put a big specular highlight right in the middle whether it should have been there or not.

I definitely agree that SS in real life is never perfectly flat. The client actually provides AutoDesk Inventor assemblies of the parts, and they have fantastic radiused corners that render beautifully. Saves me tons of time in modeling. But all the surfaces are perfectly flat.

Again I really appreciate all the feedback, and will definitely be using it to step up my game.

Lee

[Drachen]

Hey everyone, got some time after Spring Break vacation, and finishing a large Illustrator project for my client. Spent yesterday doing a lot of tweaking to my SS shader (mostly to get the grain showing decently in the render) and adjusting a large scale noise map in the bump slot to create the wavy distortions shown in Neil's tutorials. I think its better, but its got plenty of room for improvement. I have a ring of primitives around the table with either white, grey or black materials on them to reflect in the table. I didn't spend a lot of time on them, I mainly focused on the size and strength of the noise bump.

[fraggle]

what about using a vraydirt to simulate a deformation around the bended edges ti increase realism?
Stainless steel is one of the most difficult shader regarding quality vs render time.

Hey everyone, got some time after Spring Break vacation, and finishing a large Illustrator project for my client. Spent yesterday doing a lot of tweaking to my SS shader (mostly to get the grain showing decently in the render) and adjusting a large scale noise map in the bump slot to create the wavy distortions shown in Neil's tutorials. I think its better, but its got plenty of room for improvement. I have a ring of primitives around the table with either white, grey or black materials on them to reflect in the table. I didn't spend a lot of time on them, I mainly focused on the size and strength of the noise bump.

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[Drachen]

That's a pretty cool idea. I will certainly give it a try, but I don't know how labor intensive that would be per object. I do lots of these renders for my primary client, and I don't know that there is budget for that kind of time investment. And as for render time vs quality, I've pretty much thrown render time out the window! Just kidding, but I am making sacrifices on render time for quality for sure, but I have it within reason. I *think*!

what about using a vraydirt to simulate a deformation around the bended edges ti increase realism?
Stainless steel is one of the most difficult shader regarding quality vs render time.

[muoto]

why not just a blend material, one with glossy reflection (to reflect the actuel env), one with a "fake" reflection environnement (distance reflection fall off set to 10cm for instant, and a env map with soft white/black stripes) ?