Global Illumination in real life is just reflection right?
polycounter lvl 9
Hey people, I just need some clearance there. In CG rendering, there are different methods to simluate real-life light rays behaviour and etc.
I have a question regarding specularity, global illumination and reflectivity as used in CG/game rendering.
Maybe I'm wrong but from I understand, in real life, specularity and radiosity doesn't really exist . It's all just reflections right?
Then, I'm assuming specularity and GI are just simulated methods to boost the light rays bouncing effect (which in real life is simply called reflection).
For example, in this pic
The lamp photons are directed at the bed and then bounces back to the ceiling.
The ceiling gets colored brownish becasue it received the reflected photons. This is simply reflectiion right?. However in Computer Imagery they call it GI
and separates it from reflection because reflection in CG is when the surface projects cleary the bounced photons (like a mirror or a glass foo example) ?
Just like specualirty never existed in real life, it's actually just a term used to describe when real life reflectivity gathers alot of light energy (photon)?
To be short, in real life, there's only reflectivity, GI and spec do not exist ?
GI: Emulation of low-energy reflection because the surface absrobs and scatter the photons in many directions (brick wall, ceiling,objects with rough surfaces). Whcih means, the engine must render the color of the reflections?
Spec: Emulation of high-energy reflection because the surface doesn't absorb the photons rays and quickly make them bounce back in one direction (mirror, glass, water). The engine only renders the flashy glowing effect to simulate reflection?
I feel like I'm writing a lot of bullshit here whcih is hwy I need clearance.
EDIT:Ok i had someone exaplin it to me and made some tests. sorry for the stupid thread. let this sink.
I have a question regarding specularity, global illumination and reflectivity as used in CG/game rendering.
Maybe I'm wrong but from I understand, in real life, specularity and radiosity doesn't really exist . It's all just reflections right?
Then, I'm assuming specularity and GI are just simulated methods to boost the light rays bouncing effect (which in real life is simply called reflection).
For example, in this pic
The lamp photons are directed at the bed and then bounces back to the ceiling.
The ceiling gets colored brownish becasue it received the reflected photons. This is simply reflectiion right?. However in Computer Imagery they call it GI
and separates it from reflection because reflection in CG is when the surface projects cleary the bounced photons (like a mirror or a glass foo example) ?
Just like specualirty never existed in real life, it's actually just a term used to describe when real life reflectivity gathers alot of light energy (photon)?
To be short, in real life, there's only reflectivity, GI and spec do not exist ?
GI: Emulation of low-energy reflection because the surface absrobs and scatter the photons in many directions (brick wall, ceiling,objects with rough surfaces). Whcih means, the engine must render the color of the reflections?
Spec: Emulation of high-energy reflection because the surface doesn't absorb the photons rays and quickly make them bounce back in one direction (mirror, glass, water). The engine only renders the flashy glowing effect to simulate reflection?
I feel like I'm writing a lot of bullshit here whcih is hwy I need clearance.
EDIT:Ok i had someone exaplin it to me and made some tests. sorry for the stupid thread. let this sink.
Replies
" Sometimes it's hard to tell how much color is being contributed by reflection and how much is GI when looking at objects in real life."
Wut. It's all reflection brah.
If you guys wanna hurt your heads.
http://www.webexhibits.org/causesofcolor/9.html
It's more like: It's all bouncing photons, with reflection only referring to a single surface and photons being reflected off it.
GI is about light bouncing several times until its been diffused and absorbed enough.
In real life specularity and GI exists as terms to explain things, they've never been 'this is how light works', it's more about 'where will this single photon go?'
Also GI is mostly important when you have a direct light pointed at a surface, and reflections are generally most noticeable when there isn't much direct lighting (besides the specular highlight from the light source).
Rough surfaces will show radiosity but mirrors won't at all. Everything's reflections, but there's a difference between rough surface reflections and smooth surface, so we have diffuse and reflective surfaces in modern renderers.
Global illumination tends to refer to diffuse reflection, with the scattered diffuse light hitting nearby surfaces.
And caustics referring to the bounce of specular highlights, with reflected light continuing on its reflected path and lighting other surfaces.