Emmisive material as light

[nomeradona_cg]

I just want to share my latest here. using emmissive material as light source.





and this last one with background added in Ps

[Gareth82]

Re: Emmisive material as light

I think the lighting effect is very well done !, what were your settings and were you using a physical camera? Are all the lights in this scene created with emissive materials? even the one in the lampshade on the right?

I would really like to be able to set up a room's lighting like this. welldone !

[nomeradona_cg]

Re: Emmisive material as light

i want to share my findings using the image above. this test is really precious to me, and i think i want to share it with you guys.. because it was a combination of failure and success.

the background of the test was just to try emissive material in combination with playing with the vray camera but it ended up in finding more.

as a photography teacher, i know the vray camera works like a real camera ( except in DOF). in this test i lowered the fstop value to increase the effect of light in the room. i did managed to increase the effect of light in the room like in theory, but to my surprise a lot of black splotches all over the image, which actually discourage me to continue further.

one of the thing i remember in some of my previous readings. the first was some of the old thread between David Cauldwell and Dalomar and second was one of the article entitled "critical settings of Vray in MAx". this is all about the HSPH subdivision and samplings. I decided to increase the HSPH subdivion from 50(default)to 80 and sampling from 20 to 30. to my surprise the blotches somewhat decreases althouh the render time significantly increased(see 2nd image above). then i worked out by lowering the min rate from 0 to -1 (from one of dalomar's advise) and made the noise as default to compensate on the render time. this time the rendertime decrease for more that an hour to jsut 44 minutes but the black fog splotches were gone(see image 1) also this time i use the soften edges command to soften the bed sheet.

COLD a Vietnamese friend, shared one of the big thing to me ( saving the IR and Light catche map) in which actually i havent done before.

from image 1, I saved the IR map and reloaded it, and in image 3 the render time was just 23 minutes because the Primary engine (IR) calculation has been saved already and vray remembered that calcualtion already.

fourth image both light catche (secondary engine) and IR primary engine were save this time and you will see that the render time decrease again (11 mins) because the LC and Ir were already calculated.

lastly i just want to thanks David Cauldwell, Damien Alomar and Cold for the above.. and i hope the above would be useful for everyone.

[dcauldwell_cg]

Re: Emmisive material as light

Wow - its only 9.30 in the morning and I've learnt so much already today! Very interesting set of studies and findings and its great that we are all improving and helping each other to get better.
I think Damien has always councelled against using emissive materials as the main lighting in a scene, but your experiment looks pretty successful to me. I think the best lights are the ones at the side of the bed that glow - the light from these is very good. The spots look like they have some jaggies at the edge of the reflector, but the quality of light coming from them is excellent. I'll have to have a go at this and see how it works for me. Thanks for all the info on the settings - very useful.

David

[nomeradona_cg]

Re: Emmisive material as light

most welcome. indeed the very main purpose of this forum is to help each other and learn from one another.

[dalomar_cg]

Re: Emmisive material as light

those initial very splotchy results from the IR is actually due to using IR with an Adaptive Amount of 1 (its in the QMC Sampler). On darker scenes, an Adaptive amount of 1 will cause a very sparse placement of irradiance map samples. This means that there will be fairly large gaps within the samples and thus splotchy results. By lowering the adaptive amount to at least .95, but as much as .85, this issue can be resolved and you will probably be able to do with a few less hsubd.

There's another key thing that goes along with this. IR is possibly the only setting that is adversely affected by an adaptive amount of 1, so almost every other setting will still benefit from having that high of a value. The solution to this is to calculate your IR map with the lower adaptive amount, save it, and calculate the rest of the image with an adaptive amount of 1. Since you're already saving the IR map, you might try changing the adaptive amount to see if it makes things better/quicker.

[nomeradona_cg]

Re: Emmisive material as light

damien,
i followed already that adaptive amount to 0.90 on those image and i still have those reuslt. my setting is basically cloned from what you have explained on another thread. now i will try to play between these 2-hsph subdivision and the adaptive amount in the QMC sampler.
i will try to render using those saved map but this time lowering the hsph subdivision and decreasing further the adaptive amount.

thanks again.

[nomeradona_cg]

Re: Emmisive material as light

damien,
i lowered down the adaptive amount to .80 then to even .50 and lowering the HSPH subdivision, yeah the rendering has further decreaases by more than half, but the dark splotches are still there. then i increase the hsph subd,.. and the splotches gone... still not really sure on this behaviour.