[REQ] WTF does the energy loss - phong materials do exactly?

zsouthboy · Post by **zsouthboy** » Thu May 10, 2007 2:17 am

I honestly cannot tell a difference in renders between 7 and 8t1/2

Is it just a physical correctness thing?

Can someone show me an example of where it makes a difference?

Deus · Post by **Deus** » Thu May 10, 2007 2:33 am

Its actually not energy loss. Its weight loss. You will lose fat faster by rendering in 8t1/2

manitwo · Post by **manitwo** » Thu May 10, 2007 2:38 am

theres a file in your testscenes folder called "phong_energy_loss_test.igs". Render it with 0.8 and 0.7 and you'll see the difference. And yes its a physical correctness thing. If you render it with 0.7 you'll see a black outline which is physical incorrect cause that highly reflective phong-ball should reflect the background color independent from the angle.

SmartDen · Post by **SmartDen** » Thu May 10, 2007 2:40 am

here are example renders from Ono http://www2.indigorenderer.com/blog/?p=48

manitwo · Post by **manitwo** » Thu May 10, 2007 2:48 am

phong energy-loss isn't very annoying cause in most cases you can't see its effect.
but energy-loss on glossy-glass and glossy-sss is clearly visible.
for example: http://img158.imageshack.us/img158/7711 ... 988pa3.jpg (render by ZomB)

Zom-B · Post by **Zom-B** » Thu May 10, 2007 3:58 am

I have no idea what exactly should be visible here

I'm just running a 0.8t2 rendering with this scene, and it looks just the same

manitwo · Post by **manitwo** » Thu May 10, 2007 4:11 am

ZomB wrote:I have no idea what exactly should be visible here

energy loss of course

look at the right glossy sphere - it becomes very dark near the edge ("edge" seems to be the wrong word in combination with a sphere

) hope you know what i mean. Whereas the other spheres dont get dark near 90°.

ZomB wrote:I'm just running a 0.8t2 rendering with this scene, and it looks just the same

right. this is cause theres no energy-loss compensation for glossy glass and glossy sss in 0.8 yet.

hope you dont mind i put your render here zomb

Kram1032 · Post by **Kram1032** » Thu May 10, 2007 4:30 am

look at the top of the spheres!
There is a difference

Zom-B · Post by **Zom-B** » Thu May 10, 2007 4:37 am

OK ok, I got it.... since 0.8 this issue is fixed for Phong Materials, not for specular (like here the case)...
so my comparison rendering looks still the same since 0.7t7

manitwo wrote:hope you dont mind i put your render here zomb

Absolutely NO PROBLEMO dude

zsouthboy · Post by **zsouthboy** » Thu May 10, 2007 6:35 am

Okay, I usually keep up to date with nick's blog - not this time.

Thanks!

makes sense now