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I was thinking of doing a green OSL plasma kind of effect until I realized that the light would be casting against a red surface. I've been trying to visualize what this would look like with no luck, so I grabbed some green LED's and tested it out against my black / red plad bathrobe. surprisingly, you can't even see the plad effect as it all looks black, or more so, a very dull green with highlights where the light catches the fabric. The surface for my OSL project would be red metal, so i'm basically trying to figure out if I should try to be realistic and mute the red areas to a very dark green, or, just go with a straight green glow and call it a day. I guess my concern with the realistic effect is that there will be white areas where the glow should be much stronger in contrast to the red and while more realistic, may not translate properly as our expectations sometimes differ from reality.
Any thoughts or tips would be greatly appreciated!
It depends on the properties of the surface that shall be lit.
If your OSL is shining on a red 100% matte non reflective surface it should be 100% red.as it only absorb red and don't reflect anything and you wont see mirror like reflection.
If its a perfect polished metal that reflect all colors(like chrome) its should 100% reflect green like a mirror.
If your object is red metal that means that it is a reflective material that only reflect red. So it should have no green at all. But it should still have a mirror like reflection.
That is if you doesn't mean metal with red paint. And actually red metal.
edit: This was just some spontaneous thoughts on the realism on the top of my head so i might be wrong but i don't think so. But about your concern. I am not sure. Doing it 100% realistic is hard to replicate but would probably look good. But then again most material are not perfect some are dirty, roughed up etc so it would reflect differently. In the end it could look good both i guess?
This message was edited 1 time. Last update was at 2017/06/28 23:50:01
JBSchroeds wrote: I make no guarantees that the information below is accurate, but my understanding is thus:
The end effect will depend a lot on the specularity of the surface and how you are modeling the relative strength of ambient light vs the glow. In a specular reflection light basically just bounces off an object and continues on its way. The more specular the surface the more green it will look, regardless of its base color. So a red metalic surface would show areas of pure green where there's a lot of direct reflections with other areas tending to have yellow highlights (as the base red from the ambient illumination and green from the glow combines), while a red matte/diffuse surface won't change much (assuming there is good ambient light, in a lower light condition the red would actually start to wash-out towards black). So for your application I think you should probably do green highlights that blends out to yellow at the edges of the illumnated area.
The reason your bathrobe didn't look very green is because fabric generally has a very low specularity. So what you were doing was illuminating a red and black object with green light, which was absorbed in a diffuse reflection (black absorbs all colors, red absorbes all except red) and therefore ended up with something that looked pure black with green highlights (for what little specularity there is in the fibers)
The bolded is wrong I think. Why? Look at gold, its a yellow/brown metal. It does only reflect yellowish. A red metal would be like gold but red. And only have red colored reflections.
If you're doing OSL at all you're almost certainly ignoring realism in favor of an artistic effect, so talking about the physics of light isn't very relevant. Do the color combination that you think looks best, and you should still probably choose "none of the above" because 99% of OSL looks like garbage.
There is no such thing as a hobby without politics. "Leave politics at the door" is itself a political statement, an endorsement of the status quo and an attempt to silence dissenting voices.
JBSchroeds wrote: I make no guarantees that the information below is accurate, but my understanding is thus:
The end effect will depend a lot on the specularity of the surface and how you are modeling the relative strength of ambient light vs the glow. In a specular reflection light basically just bounces off an object and continues on its way. The more specular the surface the more green it will look, regardless of its base color. So a red metalic surface would show areas of pure green where there's a lot of direct reflections with other areas tending to have yellow highlights (as the base red from the ambient illumination and green from the glow combines), while a red matte/diffuse surface won't change much (assuming there is good ambient light, in a lower light condition the red would actually start to wash-out towards black). So for your application I think you should probably do green highlights that blends out to yellow at the edges of the illumnated area.
The reason your bathrobe didn't look very green is because fabric generally has a very low specularity. So what you were doing was illuminating a red and black object with green light, which was absorbed in a diffuse reflection (black absorbs all colors, red absorbes all except red) and therefore ended up with something that looked pure black with green highlights (for what little specularity there is in the fibers)
The bolded is wrong I think. Why? Look at gold, its a yellow/brown metal. It does only reflect yellowish. A red metal would be like gold but red. And only have red colored reflections.
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
- reflectance: this is the amount of light reflected back from a surface. Only totally black, light-sinking metamaterials have close to zero reflectance. Everything else throws light back at you in one way or another. One other special case of non-reflecting surface you commonly encounter are... lights. But with lights it all comes to difference in power of incoming vs emited light. That is why in bright sun mobile screens appear dimmed or even "off". (This will come back up later)
- color: except for ideal white/grey/black materials, every material creates a bias in reflected spectrum and we call it colour, no matter if it is metalic or non metalic, that is a different distinction. At this point it is also worth to mention, that lights and paints mix differently: lights add up to white (so equal R+G creates yellow), paints add up to... let's call it "muddy black" for a moment, so equal R+G create a darker, more reddish/dark olive shade of green.
- diffuse property: how much reflected light will be scattered randomly upon bouncing off. Things like powdered chalk or sanded plaster have high diffuse.
- glossiness/specularity: how much light will be bounced back in an coherent fashion, creating sharper and brighter mirror reflection. This parameter also has one subparameter, anisotrophy. Anisotrophy is a type of reflection bias - reflection is scattered more or less along different directions on the surface. Brushed metals have that property, vinyl records have that property.
- finally, metalic/non-metalic property: this one is a bit trickier to describe. Typically, specular refllection reflects light evenly throughout spectrum, i.e. materials like plastics (but even plaster under a certain angle) reflect some part of incoming light as a specular reflection, without altering it's color. Crystalic substances however, do not. For painting purposes only, what metals do with incoming light can be in a shortcut described like this: if there is white light coming at metal surface, metal surface will act as if it had a dim lightsource of it's own color "built in", so they will shift the spectrum of the reflected light. The "shift" part is the most important aspect when trying to imagine what metalic surface will do to coloured light. If there are two light sources present, one white and one coloured, then depending on relative power of those lights, those "shifted reflection of white light" will alter appearance of colored light. So your green light on red metal surface, if there is any white light present, will be reflected back as a slightly more yellowish hue of green. If there is no white light present however, green LED/laser light (which has a selective spectrum) will reflect in the same green color, without hue shift. From green LED "point of view" red materials are just grey. You can observe that using colored LEDs in the dark, surfaces of oposite color will apear exactly as grey materials of the same intensity.
But that is not all there is to "metallic feel" of color/material. In reality, we only have a couple of natural metalic colors: gold, brass, copper and various shades of warm grey/bluish grey but otherwise almost white metals (I'll skip the "rainbowy" metalic effect, as this do not apply to miniature painting). Most of what we encounter as "metallic color" in real life is anodised metal or "metalic paint" and those behave in a different way than described above. "Metalic paint" is just a ordinary pigment mixed up with tiny metal particles of one of natural metals. So it will always have two components to reflected light - diffuse of base color and a slight metalic shift of either copper, brass, gold or near-neutral white. Combined with usual clear coat on top of it and polishing it will result in having two overlaping ("compound") reflections - one in colour of incoming light and one slightly shifted. Anodised metalic colors are similiar, but because the metalic reflection comes from actual metal beneath the paint, deeper color will result in less metalic effect. In addition, anodised surfaces cannot be mirror-polished. If you want both, anodised metalic and high mirror gloss you must add clear coating, resulting in a compound reflection. But... there comes psychology and experience - we treat anisotropic surfaces as metalic, because that is where anisotrophy usually occurs (brushed, non-polished metals). So any surface whatsoever, if only it has bidirectional specularity, even if it has white/non-biased reflections, will appear metalic. And because geometries (both micro- and macro- geometries) create anisotrophy, we can imitate this effect to some extent on almost anything.
Most "non-metalic metal" painted miniatures rely on anisotrophic effects on surfaces, not actual metalic specularity. Limited natural metalic colors are also the reason why many miniatures appear heavily unrealistic - you can render/imitate deep green metals or deep blue metals, but they do not occur in real life materials. You cannot have realistic "red metal color". You can have realistic red anodised metal color or red paint mixed with copper metalic reflections or red paint mixed with neutral white metalic reflections.
Hope this clears this topic for you.
Edit: one more thing about colored light. It comes in three main varieties, hinted above. One is continuous spectrum and two are selective spectrum. White light is a mix of all wavelenghts. Typical non LED, non laser colored light will have continuous spectrum, with just strongly emphasised one particular area of this spectrum. Because of that, such colored light will reflect slightly shifted in color from metalic surfaces. You can see that if you'll take a coloured bottle and cast a colored shadow with it on a color metalic surface, using a normal bulb or sunlight. Fluorescent lights have non-continuous but complex spectrum, missing a few wavelenghts from it, so they will have a shift on colour, but will contain different wavelenghts that may be what particular metal needs for it's shifting effect. LEDs vary greatly in how selective their spectrum is, up to laser LEDs that have only a single wavelenght and do not trigger this metalic shifting effect. In your plasma example it would probably be some sort of a fluorescent one, depending on an exact physical process that occures in a plasma gun.
This message was edited 6 times. Last update was at 2017/06/29 11:27:32
It has a lot to do with the light source too.
A green LED is a laser, and represents a single color (not a mix of multiple colors that we see as a green). A green laser can only produce green light, even after a reflection on a surface.
A candle/fire can produce a reddish light. It's actually the sum of many colors (= wavelength), mostly centered around red. When it hits a surface, the surface will absorb some if these colors more than others, and the result will depend on the surface.
I don't know what type of light 40K's plasmas are supposed to emit. Green is usually not produced just by heating something (as opposed to red for instance. Metals start to glow red when you heat them enough), so it has to be something specific.
But it any case, we don't encounter green light sources very often in our lives, so our eyes are not very used to what things should look like when you shine a green light on them. It makes it very difficult to produce a good OSL effect.
Most good OSL I've seen use either a red/yellow light source (like a fire, and we're used to the light produced by candles and fire), or a white light source, which doesn't change the hues too much but mostly the brightness.
fresus wrote: It has a lot to do with the light source too.
A green LED is a laser, and represents a single color (not a mix of multiple colors that we see as a green). A green laser can only produce green light, even after a reflection on a surface.
A candle/fire can produce a reddish light. It's actually the sum of many colors (= wavelength), mostly centered around red. When it hits a surface, the surface will absorb some if these colors more than others, and the result will depend on the surface.
I don't know what type of light 40K's plasmas are supposed to emit. Green is usually not produced just by heating something (as opposed to red for instance. Metals start to glow red when you heat them enough), so it has to be something specific.
But it any case, we don't encounter green light sources very often in our lives, so our eyes are not very used to what things should look like when you shine a green light on them. It makes it very difficult to produce a good OSL effect.
Most good OSL I've seen use either a red/yellow light source (like a fire, and we're used to the light produced by candles and fire), or a white light source, which doesn't change the hues too much but mostly the brightness.
You ninja'd my edit about light sources This is all true and defines the final effect.
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
Spoiler:
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
The thing is, "green" is not an information that is sufficient to describe the light source. Two light sources that both look green to your eyes might actually be quite different in their composition.
But on to your example: if you cast a light on a white surface, the reflected light is identical to the incoming light (it's kind of the definition of a white surface). So green on a white surface is reflected green. Your first sphere clearly has white spots, which shouldn't exist if the sphere is only illuminated by a green light. So either your application produces unrealistic results, or you didn't use the colors you though you did.
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
Spoiler:
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
I adressed this in my post also (I do 3D renders for a living) - you can render all sorts of unrealistic effects in 3d software, you just showcased one of them. In real life your red metal sphere would have to be made using anodised alluminum, which will always have a clear (non-biased) component to reflection, so it will reflect a green component.
This is a fine example of difference between "physically describable" and "realistic".
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
Spoiler:
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
And to better describe what you did in those examples - you are using HDR lightning (most of those reflections) combined with an omni light source in front. Your omni light source in real life would be laser LED equivalent. On a white metal sphere you just made specular color white. On a red sphere, you just made specular reflection color red. That is NOT how real life materials work.
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
Spoiler:
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
I adressed this in my post also (I do 3D renders for a living) - you can render all sorts of unrealistic effects in 3d software, you just showcased one of them. In real life your red metal sphere would have to be made using anodised alluminum, which will always have a clear (non-biased) component to reflection, so it will reflect a green component.
This is a fine example of difference between "physically describable" and "realistic".
And that's why I wrote "That is if you doesn't mean metal with red paint. And actually red metal"
Anyway, I don't see how you can claim all I wrote is wrong when its what I see in the application.
Edit: And yes, I must admit I don't claim I know how light works in physics I did not study that. But I would think if the 3d program can make it must be good enough for painting for me atleast.
This message was edited 1 time. Last update was at 2017/06/29 12:02:54
Not wanting to sound harsh, but almost all of what you wrote is wrong... JBShroeds is closer, but still mixes things a bit. So let me be more methodical: there are a couple of different surface parameters, that get mixed in this thread. We have:
What I wrote is true for the purpose of painting. I am basing it on what I see in my 3d modelling application. For example here I rendered out for you 2 spheres.
Spoiler:
White metal sphere with green light:
Red metal sphere with the same green light shining on it green light.
I adressed this in my post also (I do 3D renders for a living) - you can render all sorts of unrealistic effects in 3d software, you just showcased one of them. In real life your red metal sphere would have to be made using anodised alluminum, which will always have a clear (non-biased) component to reflection, so it will reflect a green component.
This is a fine example of difference between "physically describable" and "realistic".
And that's why I wrote "That is if you doesn't mean metal with red paint. And actually red metal"
Anyway, I don't see how you can claim all I wrote is wrong when its what I see in the application.
Once again - 3d applications are NOT inherently realistic. You wrote many oversimplified things and mixed up some surface, metalic and lightsource properties into one. Effects you described were not wrong, basis of their explanations were. "Almost all" is not "entirely misleading". There is no such thing as "red metal" in known universe. If OP want's to be realistic you have to stick to real in-life parameters to help him.
And I didn't try to effend you, just wanted to explain to the OP true factors behind various surface effects.
Automatically Appended Next Post: Hope that calms down this unnecessary quarrel. I should have not quoted you in the first place, sorry for that.
This message was edited 1 time. Last update was at 2017/06/29 12:08:51
Wow, thanks everyone this is extremely helpful and very concise. Going to need to wrap my head around this and probably do some tests on other models to see what looks best.
This is all true and defines the final effect.
