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Surrealist.
06-22-2005, 05:08 PM
I have been wondering about this for sometime. Hoping to find an answer somehwere hidden in the docs.

When painting - in oils as an example - colors rarely if ever resolve to black unless you actually want that effect but even then dark areas of the painting and shadows are never truely black. You mix black into the color to get a deep color that may appear black but isn't. This alows for a richer looking work or art and you can even eliminate to use of black and simply resolve to the base color of an object. Say you have a dark blue as you base color. This could be as dark as the darkest areas of the picture ever get.

In LW you can adjust the shadow color, this is good but what about the shaded areas of an object?

What I mean is with all shadow options turned off on an object it is "shaded" by nature of it's shape. This shading is always where the light isn't and it always defaults to black on a gradient.

The picture is a cylinder rendered with shadow options off on the object. The black area was picked with color picker in PS and it is 0,0,0.

My question is, is there anyway to manipulate this default color and change it on an object by object basis? Say if you wanted a deep royal blue as the base color. The object would never go black. Also I would like to have the option of NEVER adding black should I choose.

Negative lights with color?

Plugins?

Shaders?

Hoopti
06-22-2005, 05:22 PM
In reality, a shadow is the absence of any color or absolute black. What makes it appear to have a color different than black is the impact of lighting. For example, on a sunny day, a shadow may appear a little bluish because the sky is actually filtering out the red light and the bounced light which is predominately blue is hitting the object and shadow covered area.

I'd owork with your lighting to fix this. If you want a good reference book to review on this topic, you can check out Nicholas Boughen's book from Wordware publishing. It's excellent.

"LightWave 3D 8 Lighting" is the title. Lighting can make or break any model you make, and is so highly understudied. I'm not a lighting guru at all, but this really helped me learn how to more effectively make my renders address the issue you're raising.

Hoop

Surrealist.
06-22-2005, 06:38 PM
In reality, a shadow is the absence of any color or absolute black. What makes it appear to have a color different than black is the impact of lighting. For example, on a sunny day, a shadow may appear a little bluish because the sky is actually filtering out the red light and the bounced light which is predominately blue is hitting the object and shadow covered area.

I'd owork with your lighting to fix this. If you want a good reference book to review on this topic, you can check out Nicholas Boughen's book from Wordware publishing. It's excellent.

"LightWave 3D 8 Lighting" is the title. Lighting can make or break any model you make, and is so highly understudied. I'm not a lighting guru at all, but this really helped me learn how to more effectively make my renders address the issue you're raising.

Hoop

Yea I gotcha, in fact a lot of the lighting tips I have in the book1001 Tips and Tricks come from Nicholas and are also in his book. So I agree whole heartedly.

I was trying to be very specific though in my post so if it wasn't clear, I an not talking about shadows.

I am talking about shading and that is something different.

Shading is the effect of "no light" rather than being a shadow. No matter what color you make the light the relative "no light" area of an object is always black and defauts to black.

The light only affects this area to the degree that it adds color to the surface area. It does not add color to the black which is mixed in on a gradient to the surface color relative to it's shape and thus the direction it faces from the light.

This is completely separate from shadow color. You will see this with all shadow options off on an object or objects.

Once you develop an eye for this you will see the difference as if you had never noticed it before and it will stand out like a sore thumb.

Yes you can use a fill light but again you loose the contrast. All a fill light is doing no matter what color it is is add that color to the surface area thus making the ratio of black to surface color change but it does not get rid of the black or change it's default color.

Agian as an example if that shading color could be changed on an object that was red you could simply make it a deep red and it would never go totally black.

It has to do with color shading from an art perspective. The best RGB example would be getting all of the grey tones by going from 000 to 100 to 150 etc on all of the RGB sliders.

Now if you want to create shades of another color it is not so simple to create the effect of say dark blue to light blue by adding more and more white. (You used to be able to move those RGB sliders like that in older versions of Lightwave)

Open Photo shop and look at Pantone colors to get an idea of shading from one color by adding more and more white.

Now in oil painting there is a technique of adding more and more black yes. But you also have the option of not doing so and mixing other colors instead.

I wish there was a way to control the color gradient on the object based on its incidence to the light. The problem with this as a gradeint texture is that it is still only affecting the surface which in turn is lit or not lit by the light which adds a set default level of black respective to the angle of the surface to the light.

I hope I am clear on this.

There is a separate channel I guess you could say that I want control of.

Examine the oil painting detail below. This is an example of the use of no black and the painting only resolves to Thallo Blue in its darkest areas. Compare to the LW image above which resolves to black.

kjl
06-22-2005, 08:00 PM
Heh, I have run into this problem a lot at work. I know exactly the problem you are referring to. If you have a white cube resting on a white plane, with a yellow light with a purple shadow color, you end up with 3 colors in your scene:

The bright side of your cube and the bright parts of your plane will be yellow.
The shadow of the cube on the plane will be purple.
And the dark side of the cube will be BLACK instead of purple. And it looks weird.
Instead of using a purple shadow color you can use a black shadow color, and fill in all the darks with a purple ambient light, but that looks atrocious, as I'm sure you know.

I have a method that works great at work, but unfortunately lightwave does not have the ability to replicate it exactly (the light model is lacking), but if I were to approximate it in LW, I would do this:

1) massive area light with no shadows from the direction of the keylight. Call it lightA.
2) massive area light with no shadows from the opposite direction of the keylight. Call it lightB.
3) lightB gets the darkest shadow color that you wish to see in your scene - in this example, it would be dark purple.
4) lightA gets the brightest shadow color that you wish to see - in this example, a little bit lighter purple.
5) Now all your keylit surfaces will have too much purple in it, so you have to suck purple out of your keylight color until it looks OK. I'm not sure if LW supports negative light colors, but you might need to go there if you pick saturated, complementary colors like yellow and purple.

Unforunately, this will be scene wide, not object specific like you want, but you could split your lights out for different objects if it was important. If you were trying to light a bowl with a bunch of fruit in it in this manner, it could get ugly, but you could still do it.

I'll try to render some images tonight if I can...

kjl
06-22-2005, 08:08 PM
I do also know that this isn't exactly the fix you were looking for, as mine is a light fix and you want a shader fix (i.e. if you have a checkboard shader on a ball, there's no way to make the dark side of the ball a uniform dark purple color, but there is a way to make it a checkerboarded dark purple that doesn't look too bad) ;)

jeffb
06-22-2005, 08:59 PM
Perhaps some type of gradient falloff using Light Incidence angle. Something that will make the shaded areas the color of the background/plane.
I'm not at my Lighwave seat at the moment so can't check on this, and my lack of sleep might mean this a really stupid idea.

Surrealist.
06-22-2005, 09:18 PM
Perhaps some type of gradient falloff using Light Incidence angle. Something that will make the shaded areas the color of the background/plane.
I'm not at my Lighwave seat at the moment so can't check on this, and my lack of sleep might mean this a really stupid idea.


No not at all. I actually experimented with this and unfortunately it still repects the black. Oh Well.

But thanks, maybe you'll come up with something.

Surrealist.
06-22-2005, 09:23 PM
I do also know that this isn't exactly the fix you were looking for, as mine is a light fix and you want a shader fix (i.e. if you have a checkboard shader on a ball, there's no way to make the dark side of the ball a uniform dark purple color, but there is a way to make it a checkerboarded dark purple that doesn't look too bad) ;)

Hey thanks for all of that imput. All good ideas. I did some experimenting with ambient color. Too bad that can't be an on an object by object basis.

What would work I think is something that would be similar to accessing the ambient channel on a per object basis but have it not affect shadows.

Inother words it would traffic cop that ugly black and give you a new "ambient color".

I don't know. There's got to be an answer someplace here.

kjl
06-22-2005, 10:52 PM
Yep, I don't think there's a way to do what you are looking for (well, I'm sure you could do it with a shader plugin, but that's actual real work ;) )

This is what I was talking about:


This is the problem you have, if I am not mistaken. Yellow keylight with a purple shadow color = yellow on light-facing non shadowed areas, purple on light-facing shadowed areas, and black in non-light facing areas:
http://www.ribsngibs.com/images/misc/lighttest00.jpg

Yellow keylight with black shadow color + purple ambient = nice shaping in light-facing non-shadowed areas, and atrocious, hideous, awful flat purple everywhere else.
http://www.ribsngibs.com/images/misc/lighttest01.jpg

LightA (as described in earlier post) - huge non-shadowing purple arealight, from direction of key = soft purple shaping on light-facing areas, black everywhere else.
http://www.ribsngibs.com/images/misc/lighttest02.jpg

LightA+LightB (as described in earlier post) - huge non-shadowing purple arealight from key direction + slightly darker purple arealight from the opposite direction = soft purple shaping everywhere, on all sides.
http://www.ribsngibs.com/images/misc/lighttest03.jpg

LightA+LightB+warm keylight with black shadow color = yellow (well, ugly peach, but whatever) in light-facing non-shadowed areas, and soft purple shaping everywhere else.
http://www.ribsngibs.com/images/misc/lighttest04.jpg

So what LightA+LightB really are are a slightly less hideous version of ambient. Plus, if you really need to, you can make multiple pairs of these and exclude them as you see fit (e.g. you could make a blue pair for the cylinders, a purple pair for the spheres, and a green pair for the cubes, and then make sure the cylinders exclude the purple and green pairs, etc., although this would rapidly become really ugly as the number of different shadow colors you begin to want goes up). Obviously this alone is still a really ugly lighting setup, but it is a more reasonable place to start adding more detail with more lights than the original yellow/purple/black setup.

http://www.ribsngibs.com/images/misc/lighttestsetup.jpg

MonroePoteet
06-22-2005, 11:43 PM
Isn't a painter really trying to reflect an ambience in the shaded-surface colors, though? LW has a "perfect" lighting system, which never (well, hardly ever) appears in nature. In nature, there's almost always sky color, radiosity off of walls, chairs, etc., and the surfaces are almost always slightly reflective. But, if these things aren't present, you get black. Some painters use black to great effect (Franz Hals immediately comes to mind), capturing an ambience with single-source directed lighting.

I'd suggest either using a three+point lighting system to fake sky and other radiosity from the environment, or set up a gradient backdrop to approximate your desired ambience and enable backdrop radiosity in the Global Illumination panel. Attached is the yellow light, purple shadow, white surfaces scene with a 7x21 Monte Carlo backdrop radiosity of the default gradient backdrop.

Another possibility is to make the surfaces slightly reflective (using raytracing or a reflection map, probably) and enable raytraced reflections. Unless there's something to reflect, though (i.e. the shadow, a room, the floor) you'll still get black.

Without radiosity, back-lighting, reflections or other simulations of real-life ambience, it's like putting your subject in the middle of a huge, dark soundstage and lighting it with a single-source light...the shaded side is gonna be black.

mTp

kjl
06-23-2005, 12:08 AM
Yeah, I would definitely do a 3-point setup or a keylight+background radiosity or a keylight+giant area skylight setup for most scenes, but for a very stylized look like the oil painting he posted earlier, it seems like you might want something with more direct control. Although in the particular case of that painting, it would probably be easiest to just do it in post...

Surrealist.
06-23-2005, 12:52 AM
Thanks for all of that work kjl, quite a bit of effort there. I know what you mean. It is not exactly the ticket but something in the right direction. I'll play with it.

Thanks Monroe too for putting out the effort. Your ideas are completely valid. Thanks.

I think by being over simple in my initial example it may seem as if I have not taken these things into account nor tried. All I was trying to do was illustrate a peramiter that is not at our control by breaking it down to simplicity.

But really the painting is the best example I could give. I just want to control this one element and it is an element a paramiter that we have no access to in LW aparently. Something I have been coming to realize.

Any ideas on shaders or plugins? Other tricks?

Hoopti
06-23-2005, 07:53 AM
Not sure if this is what you're looking for, but here's a great plug that works on shadows. Don't own it, but have heard very good things. May be worth a look at the website to see if it will help.

http://www.evasion3d.com/sd_lw_intro.html

Hoop

Axis3d
06-23-2005, 09:08 AM
If I need different ambient lighting schemes in my scenes, I tell groups of lights to affect different objects in the scene. Each light has the option to include or exclude objects in the scene. If a light excludes a particular object, than that object will not be affected by that light's settings. Also, Objects can be set to exclude lights.
This combination can make for some intricate lighting setups.

I've had to light scenes in a snow environment. The landscape objects needed much less fill light (and different color) than the darker objects that were on top of it (which needed higher ambience).

Also, the diffuse level of objects does not always need to be set to 100%. That is just Lightwave's default so that you can see something when you hit the render button.

Exception
06-23-2005, 12:25 PM
Ok, had a go at it...

First start off with 2 balls on a plane. One directional light. Left ball is ball A, right ball is ball B.

Then made the shadow color of the light blue.

Exception
06-23-2005, 12:28 PM
First image: Added a blue-to-white Light Incidence gradient in the color channel of ball A. Added a 100% to 0% Light Incidence gradient in luminosity channel of ball A.

Second image: Copy-pasted the color and luminosity channels of ball A onto ball B channels onto the green ball. Changed the alpha of color gradient of ball B to 0% at white.

Exception
06-23-2005, 12:31 PM
First image: Also added the channels to the ground object in the hope the blue shadow tones would be identical. No such luck. Changed the white end of the color gradient channel of ball B from white to the same blue and still 0% alpha. It was an error, and it should never have been white in the first place.

Second image: Just rotated the light to check if it works somewhat.

Exception
06-23-2005, 12:33 PM
First image: abandoned all hope of getting the shadow color of the ground object and that of the balls identical on a parametrical basis. Just left the object white with 175% diffuse, and it is almost undetectably the same.
Mind you, this is all with 0% ambient.

Second image: Rotated, and still works... just move the light and... voila.

Exception
06-23-2005, 12:35 PM
And here are the two gradient settings that are identical on both balls...

Surrealist.
06-23-2005, 01:06 PM
Wow Exception. That was a lesson. Luminosity. Why but of course.

OK now that's getting somplace.

To all others, great ideas and input and all valid. It's getting closer and all of these things do play a part. Now I am going to mess with some settings and post the results.

Surrealist.
06-23-2005, 02:05 PM
OK so here we go. I couldn't tell for sure from afar by looking at Execption's examples but I was afraid that luminosity would give the object a glowing effect.

Here's a closer view of a similar example with light incident gradeints on specularity with color highlights as well as the luminosity and color light incident gradients. The shadow color is the same as the darkest area of the object gradient clolor.

The problem is obvious. A great idea and a lesson just the same.

But really again back to what is needed is direct control over that default black.

Simple. There's either got to be a trick for this, a shader plugin or something. Othewise a feature request I guess.

Surrealist.
06-23-2005, 02:27 PM
Not sure if this is what you're looking for, but here's a great plug that works on shadows. Don't own it, but have heard very good things. May be worth a look at the website to see if it will help.

http://www.evasion3d.com/sd_lw_intro.html

Hoop

Thanks Hoop. That's actually a great looking plugin. It doesn't address this specifically but cool just the same.

MonroePoteet
06-23-2005, 08:23 PM
Nice technique! The "Light Incidence" gradient is a little confusing...it'd be nice if it was the polygon normal angle to the light (0 degrees = pointing at light, and go all the way to 180 degrees), but seems to work. Add a little Interpolated radiosity to darken the close-up shadow...very nice!

mTp

Surrealist.
06-24-2005, 01:50 AM
Yea it is pretty cool. Nice example. Looks good!

Exception
06-24-2005, 02:24 AM
Surrealist: I don't really understand the problem anymore... What glowing effect?

The luminosity just makes the default brightness of the object enough so that the basic material color will show up. Using that gradient it actually won't make the color of the material itself luminous (such as the green in the example above).

Surrealist.
06-24-2005, 05:03 AM
Surrealist: I don't really understand the problem anymore... What glowing effect?

The luminosity just makes the default brightness of the object enough so that the basic material color will show up. Using that gradient it actually won't make the color of the material itself luminous (such as the green in the example above).

Balls left to right:

No luminosity
100% Luminosity
Luminosity filtered through the light incidence gradient.

OK I know that is a stark example. If you look at your examples though, and mine. They have a level of luminosity present.

That's all I am talkng about.

MonroePoteet
06-24-2005, 11:38 AM
Looks like maybe you had the same confusion I did with the Light Incidence gradient. The input value to the gradient is the angle between the Light and the surface, where "90 degree" means pointing at the light, and "0 degrees" means sideways to the light. They don't allow values less than zero (i.e. pointing AWAY from the light), so anything on the backside of the object will be the luminosity of 0 degrees. It'd be nice if they did, but they don't. Given this, I think you need to reverse the values for your gradient.

So, using a Light Incidence gradient you can't have the backside of the object have variable luminosity, just a constant value specified at 0 degrees (i.e. the edge). Using a sphere as an example, if you set the 90-degree value to 0.0, and the 0-degree value to 100.0, the luminosity will increase on the surface exposed to the light, giving you that "glow" effect.

What I ended up doing is using a small value for the 0-degree (20%) to light the backside slightly, and then just trying to make the transition across the light terminator even. Adding another gradient slider with a value of 0.0 and putting it at about the 30-degree mark controls the luminosity increase across the terminator. If you put it too close to 0 degrees, you get a sharp, dark line at the terminator. Too far away, you get glow on the front/lit side.

mTp

Surrealist.
06-24-2005, 11:24 PM
Looks like maybe you had the same confusion I did with the Light Incidence gradient. The input value to the gradient is the angle between the Light and the surface, where "90 degree" means pointing at the light, and "0 degrees" means sideways to the light. They don't allow values less than zero (i.e. pointing AWAY from the light), so anything on the backside of the object will be the luminosity of 0 degrees. It'd be nice if they did, but they don't. Given this, I think you need to reverse the values for your gradient.

So, using a Light Incidence gradient you can't have the backside of the object have variable luminosity, just a constant value specified at 0 degrees (i.e. the edge). Using a sphere as an example, if you set the 90-degree value to 0.0, and the 0-degree value to 100.0, the luminosity will increase on the surface exposed to the light, giving you that "glow" effect.

What I ended up doing is using a small value for the 0-degree (20%) to light the backside slightly, and then just trying to make the transition across the light terminator even. Adding another gradient slider with a value of 0.0 and putting it at about the 30-degree mark controls the luminosity increase across the terminator. If you put it too close to 0 degrees, you get a sharp, dark line at the terminator. Too far away, you get glow on the front/lit side.

mTp

Yea, I'm with you. I tried the otherway around too. I guess I just wanted to illustrate the idea that there is luminosity there, which there is. The other way around it just shows up on the back of the ball.

Your technique is solid though in your use of the gradient as you sated above. Good work by the way and thanks for chipping in. So I think it's all good. I like what is comming out of this even if it is noit exacly what I envisioned.

The thing is for what I was trying to do, luminosity kind of kills the effect. If I play around with the settings though as you have prescribed I might find something I like. We'll see. maybe this in concert with some other tweeking in diffuse and maybe even a shader and of course radiosity. Whatever the outcome I appreciate the imput because it has given me plenty to think about.

Thanks to all you guys for chipping in on the challenge. When I get some sleep, I'll post some of my own tries at it with what I've learned here.

Thanks.

Surrealist.
06-25-2005, 03:31 AM
OK a little update.

This is just the idea of the color gradient with radiosity and no luminosity. The background color was set to white so it would not interfere with the radiosity colors or add black

In its basic concept getting closer to the artistic effect I am looking for. Basically. That is strictly in terms of treatment of color.

The black is now just hiding out on the bottom of the ball. It's tolloerable as the ball at least shows the gradient of color.

Of course there is quite the render hit with radiosity. Then there is going down the path of faking it with fills etc. A step closer. (The painting again to compare)