shiny metal finish

[jim c]

I'm trying to get a shiny metal look, like what they had in the Tron Legacy movie (I've attached a screen shot from the movie to demo what I'd like to get). Is this something the basic reflective material can accomplish or am I looking at the wrong thing? I'm using it with the spec set to Anisotropic which seems to be closer to what I want. But I'm not getting what all I need to modify. I think the look comes from the way the specular highlights come across but I could be wrong. Any ideas on this? I suck at doing shaders so any help would be most appreciated!

Edited August 25, 2011 by jim c

[hopbin9]

That's more of a blurry reflection then shinny.

[Jason]

It looks if you use the Mantra Surface shader with blinn reflections with an angle of, say, 10. Don't use any Diffuse shading unless you want a slight dusty coating to give you purchase in the darker areas.

[LaidlawFX]

So this is kind of a breakdown of the frame as a whole.

There are a couple different specs/reflections on the bike. The mantra surface shader can do it, but you'll need to apply a couple different shaders for the different components of the bike. Suffice to say it is not one shader for the whole bike. So in your own scene you'll have to be aware of what gets what treatment. This can be noticed from the front tire section with a wide spec(blinn like), and the wheel cover right above it, which is sharp(phong like).

Also some of the things that define the shader the most are the lights and the reflection cards in the scene, like the white spec on an apple there are a bunch that define the outcome of this look. I would do this all through object based reflection. First make sure you have a good env sphere hdr map, a type like a studio car commercial settup not one of a typical outside environments. Either that get some light cards, hdrlabs.com has a good set of cards half way down the page. You can user PBR with those cards in the areas light to get it to work fine(I believe doing that specifically will trigger the light based reflection and no just object based).

My favorite def reflection setting is quality 10(start high and lower it, for efficiency sake) 1.52 blur angle, intensity .6, color white, 0 anistropic, and blinn shaded. Blur reflection take longer to render for smoothing of the color, so it can be cheaper to just blur the light card more depending on the shot.

The blur angle reacts differently to the dif lighting models so when testing stick with the light model first, you're probably safer with blinn than phong.

Make sure you're UVs are good when playing with the anistropic. I feel like Houdini is a lot more responsive to that than maya. So I don' think ths look is completely UV less unless you shadeing via the mesh and attribute route, which it doesn't seem like you are.

Also there looks like 4 to 5 different sources causing those long specs, at minimum 2 across the top and striking the side. A third would be from the bottom rim. It's hard to tell from the static frame.

[jim c]

Thanks for all the detailed answers! One question - if I don't have H11, which I think is required for the MAntra Surface material, how would I approximate that in H10?

[jim c]

@laidlawfx

For now I want to try and make this work using the micro poly renderer. Given that, what are my lighting options? I have a GI light in the scene, so that would obviously get an environment hdr. For "object based lighting", would I then just reuse that same hdr as the reflection map for any of the materials that have reflection turned on?

Maybe another way of asking, how do you do light cards in Houdini without using PBR? Is that even possible?

Edited August 27, 2011 by jim c

[jim c]

This is a test, just the GI light and the hdr image set to all the reflective surfaces env map.

[LaidlawFX]

@laidlawfx

For now I want to try and make this work using the micro poly renderer. Given that, what are my lighting options? I have a GI light in the scene, so that would obviously get an environment hdr. For "object based lighting", would I then just reuse that same hdr as the reflection map for any of the materials that have reflection turned on?

Maybe another way of asking, how do you do light cards in Houdini without using PBR? Is that even possible?

All Lights, and yes lights cards work with out pbr....

In not answering your question unless you are in h10 I wouldn't be hesitant of PBR. In h11 it works pretty well, esp with area lights(everything outside of points and distance). Also the only difference between micropolygon and micropolygon PBR is the shading process, each use the same dicing process, so if that is your deciding reason you can think of that. I'm currently limited to raytracing, and I have been able to use env lights with no problems. Haven't done much area lights, but I'm not in that area right now. Also if you are limited to a small thread count, I would def take the time to optimize and not use pbr, if you got some extra threads to kick about I would just run with area lights.

Ok to be more specific. You can do a poor man's area light, with the light card texture applied to a grid, so that it can do object reflection, and then use a point light with the spot light modifier on it used along the card.

In trying to answer your question: You should be able to just use area lights with no problem, if you adjust your noise settings correctly. Don't crank up pixel samples as your default in getting rid of the black noise of the area light or the noise of blurry object reflection. To get rid of blurry reflection noise crank up the quality on the shader first, then follow with the pixel samples on the out. Pixel Samples is a big slow down, while it is a great quality adjuster that all old school people love it should not be the first thing you crank up. If you have noise from the blur you are cleaning up you have to kind of balance with that too. To get rid of the black noise from the area lights adjust the samples quality up minimally say 20 not 120 in the area light. Next if you are in pbr use the min and max ray samples, use max first and don't worry about cranking it "high" after 64 it does it's own thing and only slowly turn up the min, that will cause good improvement but it is slightly more costly, esp if you have a lot of dead space in your framing. Then follow with pixel Samples. Don't use Dicing by default it is pretty time costly.

Side Note: Make sure your environment light map is in the Houdini Environment Light format(Houdini Imaged Based Light, HIBL). Use a small blurry map. Like 512x256 is ok.

Yeah you can use your Latitude and longitude map on a sphere for your object based reflection. Use a larger sharper map(unless you are cheating blurred reflections)

[jim c]

Laidlawfx thanks for the detailed response!

>Make sure your environment light map is in the Houdini Environment Light format

What is that? I googled a bit and didn't find much. Is this simply an HDR file that has a 360 wraparound? Is it the result of converting a set of 6 hdr images into a rat using houdini's isixpack command?

I have Vue 9 at home and it can create 360 degree HDR images. Other than using icp to convert the image to the RAT format, is that OK to use as the environment map?

Another side question for light cards. In Modo it's possible to have any geometry emiot light by simply changing it's material properties and crank up the luminance amount. In Houdini, if you do NOT use PBR, is it possible to make a surface shader that emits light? From what I've been seeing looking around, it sort of seems like this should be easy to do, but maybe I'm misunderstanding how things work.

[anim]

you can use HDRI in LL format (360*180) and it will work correctly with Environment light, no need to convert it to another space

but as image format RAT is the most preferred, to save conversion time each time you render since it is converted to rat anyways

any geometry can be turned to light with Geometric Light in H11

as light cards you may want to use Area Lights, which can be also textured

but for many cases like this, you don't need light card to actually emit light, just to be reflected in objects and for that purpose you may use any geometry with constant shader textured if you wish

[jim c]

but for many cases like this, you don't need light card to actually emit light, just to be reflected in objects and for that purpose you may use any geometry with constant shader textured if you wish

Finally get hit with the clue bat! OK so the light cards themselves don't actually emit light? They are just there to kind of bounce it back into the scene? Hence the suggestion to put a point light in front of the card?

Sorry if this is obvious, but I'm not a photographer and I've never been any good at scene lighting/setup.

[anim]

it depends on what you want

in photography there are passive white cards to just bounce the light back to the subject and don't emit any light by themselves

or you have large white translucent card in front of your light to diffuse the passing light and make sort of large area light

or many other types

(if you want to mimic real light behavior, light bouncing etc. you can use similar techniques with PBR, but usually you will lit the scene with area lights and/or HDRI environment)

in 3d the emitted light from light source only affects diffuse surfaces

for reflective surfaces the emitted light has no effect on the look of the surface, but it's look is created by reflection of the scene (including light sources)

so for scene with just reflective shaders you don't need any light, just objects with constant shader or HDRI map or anything what will reflect in scene objects

but if your shader is partly diffuse partly reflective, you'll need your light to illuminate diffuse part and be reflected in reflective part, (area lights in H11 do that by default)

what LaidlawFX is suggesting with point light and grid is sort of fake area light. Point light will provide light for diffuse part of your shader and grid will be seen in reflections. this will not produce soft lighting/soft shadows, but it may work ok for some cases. But it has nothing to do with light bouncing off the card

and since in picture you've posted I see almost no diffuse reflections I suggest you to do what Jason said and you don't need mantra surface for that, there is some reflective shader in H10 which allow you to set angle to blur your reflections, then just use constant(or textured) planes/geometry to make environment which will be reflected or use HDRI environment map, and if you want cheap way use textures with soft edges for the planes or use blurred HDRI map and then you can keep your reflections specular, it will not be the same but may work

Edited August 29, 2011 by anim