What would be the results if light didn’t reflect? I can see a strange landscape of slashed black shadow with slashes of colour but its gonna cause all sorts of problems. And I imagine some huge ones…probably.
Well, imagine what would happen if everything was made of stealth bomber stuff, and the only EM available was radar…
dv said:
Well, imagine what would happen if everything was made of stealth bomber stuff, and the only EM available was radar…
Question was inspired by a program about that atomic bomb and atomic shadows and got me to thinking about light after being emitted only being absorbed. Shadows would be black as. Plants would have to grow differently, things that move would probably need sonar as well as eyes.
Driving at night would be tricky with normal headlights. Hell driving during the day on a dappled or cloudy day would be a challenge.
Skunkworks said:
dv said:
Well, imagine what would happen if everything was made of stealth bomber stuff, and the only EM available was radar…
Question was inspired by a program about that atomic bomb and atomic shadows and got me to thinking about light after being emitted only being absorbed. Shadows would be black as. Plants would have to grow differently, things that move would probably need sonar as well as eyes.
Driving at night would be tricky with normal headlights. Hell driving during the day on a dappled or cloudy day would be a challenge.
A less extreme scenario would be to have some things re-emitting some proportion of the light they absorb.
A less extreme scenario would be to have some things re-emitting some proportion of the light they absorb.
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Which would be normal activity: light is absorbed, temperature increases, at some point the thermal radiation will equal the incoming radiation in power.
I was happy to play with and be educated by some of the hypotheticals and scenarios it might offer and was perhaps not explicit in my parameters hoping readers might get the vibe about which I am unclear myself but now being informed it is impossible I thank you for your diligent application of principles and lack of imagination.
dv said:
A less extreme scenario would be to have some things re-emitting some proportion of the light they absorb.—
Which would be normal activity: light is absorbed, temperature increases, at some point the thermal radiation will equal the incoming radiation in power.
OTOH, we can have pigments that have non BB spectra, although in the real world such things tend to reflect light to some extent and the colour we see is due to selective absorption.
but now being informed it is impossible
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Who said it was impossible?
I think the question is tantamount to saying what if only non-reflective materials existed. At some point, that was the case, pretty much … Balls and clouds of gas and plasma do not reflect, and that was all that existed for hundreds of millions of years at least. My answer was serious: what would happen is that the materials would get warm from radiation and would, themselves, radiate.
But now thinking a it harder inspired y DV everything I see is reflected which is the colours and my question may have been nonsense and I may need some reality where most things are really really non reflective.
Yeah, but if it emits a black body spectrum things need to get rather warm before they become visible
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Well I need a ruling then. Are we just talking about visible light, Skunkworks?
dv said:
Yeah, but if it emits a black body spectrum things need to get rather warm before they become visible—
Well I need a ruling then. Are we just talking about visible light, Skunkworks?
I yam going to bow out cos I am a bit dim and have encountered obvious facts which I had not considered. Turns out I was thinking light that doesn’t bounce back unless it is seen in light. Or something. I am weary.
OK I was thinking of a world where light might act as it does with a strong beam at night where you can only see within the beam. And I get that is real world, but extending that to a world where light only illuminates or total shades, very on or off.
And that is badly explained again.
Skunkworks said:
But now thinking a it harder inspired y DV everything I see is reflected which is the colours and my question may have been nonsense and I may need some reality where most things are really really non reflective.
Or, as I said before, you have stuff that re-emits some of the light it absorbs rather than reflecting it. True, the laws of physics in that world would be a bit different than in the real world, but that’s no big deal for a hypothetical.
In 3D rendering, we always work with a simplified model of how light behaves, as a perfect simulation of the real laws of optical physics is computationally impossible. So we have to compromise and use various simplified models of reflection and light transmission, etc. And we use surfaces that glow in a way that’s not physically accurate but still looks good.
When I’m developing a 3D scene I generally start out with a fairly simple optical mode, with reflection turned off, and only turn on the high-quality optics once I’ve got all the objects where I want them. So I’m kinda used to working in a world with no reflection.
When I’m developing a 3D scene I generally start out with a fairly simple optical mode, with reflection turned off, and only turn on the high-quality optics once I’ve got all the objects where I want them. So I’m kinda used to working in a world with no reflection.
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By ‘no reflection’ and ‘reflection turned off’ do you mean specular reflection?
Stealth said:
When I’m developing a 3D scene I generally start out with a fairly simple optical mode, with reflection turned off, and only turn on the high-quality optics once I’ve got all the objects where I want them. So I’m kinda used to working in a world with no reflection.
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By ‘no reflection’ and ‘reflection turned off’ do you mean specular reflection?
Pretty much. But it’s complicated.. :) I turn off genuine specular reflection, but I generally leave “fake” reflection turned on so that surfaces still have highlights, otherwise they look flat and it can be hard to see where stuff is unless the scene is really simple.
From http://www.povray.org/documentation/view/3.6.0/347/
Highlights are the bright spots that appear when a light source reflects off of a smooth object. They are a blend of specular reflection and diffuse reflection. They are specular-like because they depend upon viewing angle and illumination angle. However they are diffuse-like because some scattering occurs. In order to exactly model a highlight you would have to calculate specular reflection off of thousands of microscopic bumps called micro facets. The more that micro facets are facing the viewer the shinier the object appears and the tighter the highlights become. POV-Ray uses two different models to simulate highlights without calculating micro facets. They are the specular and Phong models.
When using true specualr reflection, POV-Ray has various parameters that affect how realistic the reflection is. Eg, you can specify Fresnel reflection, so that the reflectivity of the surface is affected by the index of refraction of the material.
See http://www.povray.org/documentation/view/3.7.0/348/ for further details.
Skunkworks said:
What would be the results if light didn’t reflect? I can see a strange landscape of slashed black shadow with slashes of colour but its gonna cause all sorts of problems. And I imagine some huge ones…probably.
wookiemeister said:
and without reflection that would work how?
Riff-in-Thyme said:
wookiemeister said:
people would have torches for eyes
and without reflection that would work how?
so they could see each other
I wonder what the world would look like if we had no diffuse reflection, but only specular reflections (and the specular reflections would be confined to the main macro scale reflections, not allowing any micro facet specular reflections)
what would the world be like if we didn’t have zinc?
Stealth said:
I wonder what the world would look like if we had no diffuse reflection, but only specular reflections (and the specular reflections would be confined to the main macro scale reflections, not allowing any micro facet specular reflections)
But roughly speaking, if everything had no diffuse reflection but it did have a significant amount of specular reflection then it would look like highly polished metal, ceramic or (opaque) glass, although metallic reflection has a tendency for the reflected light to pick up the surface colour of the metal.
FWIW, pure diffuse reflection makes stuff look like plastic. If the diffuse highlights are small, the surface looks harder, with weak diffuse reflection and large highlight size, the appearance approaches that of plasticine or cloth.
With plasticine porters with looking glass ties
probably closest thing there is to a perfect isotropic absorber would be a black hole
another question is would any light sources exist?
transition said:
another question is would any light sources exist?
>>Yes, Skunkys original question and my secondary question both relate to reflections. Light that is emitted from a globe/fire/star are not reflections.
Not sure, we’d have to get to the technical details of what ‘reflections’ are, and draw a line maybe.
http://en.wikipedia.org/wiki/Reflection_(physics)