Coloured spec maps

Rick Stirling

So we've been told in the past that coloured spec maps are better..because....

Well, here is the thing, I was trying to write a tech docfor 3d palette discussing the use of spec maps (as part of a mapping discussion) - what they are, why we use them, but I could find NOTHING on the difference between black and white and coloured spec maps apart from vague theories with no proof.

Coloured ones are supposed to add a colouring to the reflection, and some people say that it works as a simple shader, increasing saturation around the terminator of the lighting, but I still can't find direct proof.

Another thing I was considering: Does it make that much difference? Sure, in high end high poly pre-rendered cinematics, but in a game engine will people even notice the subtle difference? Of you have 20 Orks/Space Marines/Hell Demons running at you, do you say "Oh, I like his rosy cheeks!" ?

JordanW

i think the question 'does it matter' could be said about a million things that we're doing in next gen games. I do however always promote the usage of color in spec maps, just because it does help at a bit of detail to your objects. I remember one good use a few months back was to add metal flakes to some stonework. The stone was a paleish color while the spec had really strong yellow/gold flakes in it, it created a nice effect.

I think the point you should try to make is that you should never feel that a specular HAS to be monochrome and that experimenting with colors will often times yeild very good results.

KDR_11k

Of you have 20 Orks/Space Marines/Hell Demons running at you, do you say "Oh, I like his rosy cheeks!" ?

Yes because bad specmaps will make them look like 20 oversized action figures. Also, many games have scenes that don't have that much action, like cutscenes. Other games might involve no action at all (adventure games, for example). A game like Final Fantasy needs colored specmaps and SSS even though Unreal Tournament 2007 might not.

Also: http://mitglied.lycos.de/KDR_11k/pics/pimp/ingame_front.jpg. The "purple" parts are in fact black/grey, the purple comes from the specmap. The skin has a bluish specularity and looks less plasticy than standard Doom 3 characters.

MoP

You can make "metallic paint" stuff look really cool with coloured spec maps. Also iridescent stuff.

For an iridescent beetle, say the diffuse colour is dark brown/black, you could give the spec a really saturated green colour, and that would give a really cool effect in game.

Likewise metallic paint for cars... generally easier to make certain materials look a lot more realistic with a coloured spec map.

Rick Stirling

Can anyone provide links to technical discussions?

RazorBladder

[ QUOTE ]

For an iridescent beetle, say the diffuse colour is dark brown/black, you could give the spec a really saturated green colour, and that would give a really cool effect in game.


[/ QUOTE ]

I had a go at this exact thing a couple of months ago in doom 3.

Beetle Green Specular
Beetle Yellow Specular

Obviously now I look at it there's tonnes of areas for improvement and I'll go back and fix these at a later date I suspect.

pior

I'm unsure how the actual math behind that works, but it sure has an effect. It might not be 100% noticeable at first glance but man these things are powerful. And even better, it's a pleasure to work with!

Like on the metal/aged combo here



also on the red tube on the back. I used a yellow spec for that tube and it helped giving a ... different look

These maps can be funky

http://pioroberson.com/modelpics/ab_s.jpg

You might want to have a look at some doom3 textures for that, you can open the pak files with winzip and browse them easily. Some nice examples in there.

Rick Stirling

Yeah, I would but I'm on a mac at home:) I'n not buying a Mac copy too.

Eric Chadwick

Rick, I learned a lot from this thread, back when my nick was "posm"...

http://dynamic.gamespy.com/~polycount/ubb/Forum8/HTML/004130.html

Funny how the old board is still there, accessible but untouchable.

Rick Stirling

I'm not disputing for a second that they look better, but if I write a document thats says "Colour ones are better because I say so," then I have failed.

People always seem to use blue for skin specular, and when I ask why most poeple say, becuase umm..becuase...because he did it that way. Some people say that its because the earth has a blue skin, therefore things get tinted blue - yet thats assuming our models are outside on planet Earth on a sunny day.

So when I say I want technical explanation of why it is better, I CANNOT accept someone saying "Its better."

I can easily explain why a 24 bit image is better than an 8 bit. I can see the difference, but I can explain very easily the technical reason (there are more colours). I can explain why normal maps are better than grayscale bump maps, because I can see the difference and prove the technical difference. when writng a tech doc "Because" is not sufficient.

MoP

Rick: Make/find a normal-mapped human face texture with a metallic iridescent green necklace or something, render one with a greyscale spec map, render the same angle with exactly the same textures but a colour spec map (make sure it looks GOOD first!), and put those side by side in your tech doc.

Let the reader's eyes do the explaining.

Rick Stirling

Gah! I'll ask a coder Course, i'll have to convert the explanation from binary.

ElysiumGX

I wouldn't say one is better than the other, but colored spec gives the possibility of creating a wider variety of appearances for materials. For example, my dad paints autos and motorcycles. One car recently had an orange finish, but a metallica purple glitter in the sun. I could have an orange color map, with a noisy spec map colored purple. I used one to get a more sparkling mineral effect on rocks, and played with emulating unique clothing fabrics. Shades of black and white are flat. Ask any painter. Like you said, there are more colors. I'm not claiming to have any idea what I'm talking about here. :P

MoP

Heh, ElysiumGX, you say "I wouldn't say one is better than the other", then go and explain how coloured maps are better than specular maps

ElysiumGX

Shhh...I was trying to fool Rick into listening.

[ QUOTE ]
if I write a document thats says "Colour ones are better because I say so," then I have failed.

[/ QUOTE ]

How about "Colour ones are more useful because artists say so, you nerds!!"

Faucet

As far as why blue specs on skin tones... what Per said. To further, straight skin tones look very zombieish. Making the skin color redder than it should be and using a blue spec makes for a nice translucent feel and you should really have a redish shadows and greyish hotspots. if it's a violent blue you've probably gone too far with the blueness.


Also keep in mind specular hotspots are not really a true to life thing to begin with but rather hack to simulate very small and varied reflections that appear because no surface is perfectly smooth. So describing why colored specular highlights look better than uncolored ones in scientific terms isn't easy.

http://www.androidblues.com/shadetut.html
^ An old Stahlberg skin shader tut that got me to think a bit about it.

KDR_11k

I think Stahlberg said it's to have the diffuse emulate SSS. Basically the specularity only hits the top layer of your skin (white) while the diffuse would be influenced by the lower layers (red). Since specularity is added you need to reduce the red in your spec map so it counteracts the red in your diffuse map.

Rick Stirling

See, THATS the stuff I was looking for!

Per, the opposite colour thing is what I was looking for, an explantion of why blue was used in skin, not just "use blue"

KDR, Again the stuff I was after. I mentioned in my very first about it emulating the saturation at the terminator, but I wanted some backup, and thats the stuff I was looking for.

I've been painting colour spec maps for a while, but was blindly following rules that might have been half truths - blue faces etc. I was painting my ears a much richer red in the spec map for SSS emulation, and it looked better, but like a I said, sometimes "It's better" Simply isn't enough of an explantion.

John Warner

are you just talking about skin?

different types of objects have different physical qualities that may result in a different reflection effect. all metals, for example, have a colored spec hit. blue metal, blue spec hit, etc etc.

didn't everyone know that? am i missing something?

Steve Schulze

This is all a little confusing. Could someone post a couple of examples of good coloured specular maps and their result, particularly for the likes of skin where you don't use an imediatly obvious colour...

Mark Dygert

This is off topic but how long until we have layered, animated colored spec maps that play durring certain animations? How cool would it be to see a charcter blush when they are embarrased. Or Watch a soldiers face drain of color before going into combat, or when he is shot and dying, watch his face go white. I wonder if we could use animated spec maps on say, a gunshot wound? It could have a surge of color around a wound which if it is on cloth could look like soaked blood. I am not sure if we could get spec maps to do this stuff or if this kind of thing is done with specailly designed "shaders" which are game specific. But these are the things I would like to see in the next round of games, artists and animators need these kind of tools to tell the stories.

KDR_11k

That'd be diffuse, not spec. But I think you could do that in everything since Quake 3. Many games nowadays add wounds where the model is hit, too (Doom 3 is very noticable but it uses too large wound decals).

Eric Chadwick

Jackablade, digging around in Pior's WIP folder, I found these handy htmls. Cool to see the flats next to the finished results.

http://pioroberson.com/modelpics/info_kid.htm
http://pioroberson.com/modelpics/info_aquaboy.htm

Pior, what's the deal with the eye-specular you have in the Kid's fourth texture flat? I guess you're using that as an emissive pass on the eyes, in addition to the third-flat specular pass?

I'm thinking that you don't have control over specular width (to get those tight eye-reflections vs. the broad specular width for the skin), or the card sucks at specular... so you baked it in...?

MoP

EricChadwick: I think the kid's 4th texture flat there is the diffuse map for the hair and the eye in the corner is just the highlight overlay for the eyeballs.

I think Daz mentioned this a while ago, but for realtime eyes, instead of painting a sharp specular highlight onto the eyeball geometry itself, duplicate the front few polys of the eyeball, move them forward a bit, and use an opacity-mapped texture as a static highlight - so even if the eyeball rotates, the highlight will stay where it is.

I guess that's what that section is for on Pior's model.

pior

Hey Vig for a nice example you might grab Harl's Worldsoldiers skinpack for QIII. I remember he actually painted multiple instances of head textures and blended/animated them with a shader. I think the avatars he did for the selection screen also had animation support, freaky

Eric, yes I went for a painted-on specular for the eyeballs.

I tried it first with a 'correct' specular definition (high spec on the eye) but I disliked the results : at some point the hotspot, while looking good, was only to be seen on one eye or the other (model had no modelled eyes, they were simply here thanks to the nmap).

To avoid that I toned down the eye specs, added a little 'pushed' polygon shell in front of the eyes and gave that a prepainted specular spot. With a bit of selfillumination it faked a bright spec effect quite well and gave me a complete (even if hacked!) control over specspread.

Since the shell was slightly floating in front of the eye surface it gave the painted spec a parallax effect that faked 'reflection slide' as the model rotates.

That was inspired by a post Daz and/or Soul made a while back about the Bond models they were making.

I think it's really handy even if it goes 'against' the so-called theory about next gen chars

With the kid I wanted to stay with the same falloff setting for the whole model, but I think that in the case of a strong nextgen game engine one could define 'specular spread' on a permaterial basis thanks to a shader. Still need to play with that myself

[edit] Ha Morpheus beat me to it. You win a cookie Moppy!