basic lighting advice

[agrmrs]

hi friends currently i'm trying to understand lighting .... i lighted up a room with a lightbox light



also given a fall off vlue and set that decay line just back from the back wall




issue-1
but my back wall gets lighted up in a rounded manner ( not a square shape ) ......i have no idea since my light comes through that square windows this happens when the area light's on as well





issue-2
i'm not sure about this but i think my back wall is bit lighter comparing to the other walls ....but it shouldn't be happened since i've given the light falloff ( again comparing to the other walls ) .... i think the far the light goes the more decay it has ........

if someone can explain me what happens in both situations it would be highly appreciate i attached my file too
thanx

[Diurno]

mmm which versione of SI do you use? cause i can't open your scene (i've 7.01).

BTW , i tried to recreate your scene, and i've your issue if I use Linear Fallof; try to set the Fallof to Light Exponent and set it ti 1-100

[origin]

mentalray area lights are fake, they are spot lights with area shadows. AFAIk 2011 has true area light.

[Hirazi Blue]

I don't know why, but the end falloff in the scene you've uploaded is way too low. It doesn't nearly hit the far wall, like in your image above. Increasing the end falloff parameter helps. So maybe there's the problem...

[agrmrs]

Hirazi Blue - yeah dude u r correct .... me checked it again .... it's true that it's behind the wall but the decay distance isn't enough to light up the whole back wall .... i fixed it ....many thanx for the idea

origin - yeah ....... can u tell me what is "AFAIk 2011" and where can i get it .....thanx

Diurno - ohh sorry mate i couldn't mention the version........i'm using 2010... yeah light exponent is the option to go ...... thanx for dedicating ur time to overcome the issue

having played with the box light i set up a infinite light to get the effect of the sunlight ....... then i used GI ( only GI for now ) to illuminate the scene further more .....i'm not happy with the teapots locating near the camera since they seem dark ...... plezz give ur critics about the below image since i really need to improve my indirect lighting knowledge ;;)


thanx

[Diurno]

you're welcome.

I think Origin mean that Softimage 2011 has true area lights. ASAik stand for As Far As I Know

[agrmrs]

you're welcome.

I think Origin mean that Softimage 2011 has true area lights. ASAik stand for As Far As I Know

opsss my bad ..... can u gimme some critic about my latest gi render too thanx

[Diurno]

well, i'm not really expert, but for my opinion:

that's not a bad start; the major "bug" i see are:

-the angles of the walls, u had bevel that? i suggest to make a really small bevel to help tha light to cast there.

a question: do you use classi photon Gi or the Importons?

[agrmrs]

well, i'm not really expert, but for my opinion:

that's not a bad start; the major "bug" i see are:

-the angles of the walls, u had bevel that? i suggest to make a really small bevel to help tha light to cast there.

a question: do you use classi photon Gi or the Importons?

ohh yeah i've beveled that .... i'll reduce it from the selection explorer ......... i'm using classic GI photons ...... i came to know that lots of artists uses final gather to get a better quality render...... have u used it and can u tell me the benefit if so can we use final gather only, to render the scene with a better quality ? thanx

[Diurno]

well for my knowledge, the better way is to use both of them, cause the Final Gather take all your photons and blur/merge the color, avoiding the dirt effect caused by your GI.

For some scene i use also ONLY Final Gather, all depends on your target and on your scene.

Can you post your GI settings? it's more easy to help with them ^^

[agrmrs]

thanx mate ..... i'm also gonna follow a FG tute ....... here are my GI settings

[agrmrs]

i read the manual too below is what it says about final gather

"Final gathering is a way of calculating indirect illumination without using photon energy. Instead of using rays cast from a light to calculate illumination, final gathering uses rays cast from each illuminated point on an object’s surface. The rays are used to sample a hemispherical area above each point and calculate direct and indirect illumination based on what the rays hit "

to me it's bit complex to understand .... can someone simplify it ..... what i found from the net & understood was , final gather rays cast from the camera and samples the scene ...... do no weather i'm correct or wrong .......thanx

[agrmrs]

hi friends currently i'm trying to render the same scene with GI + FG ....... as a beginning i came out with the below result ......



i'm pretty happy that shadows look more realistic in this render... but overall render is a bit dark ..... i can increase the GI photon intensity a bit or probably it can be tone mapped ( i've seen but haven't tried the tone mapping ).....but before that i needed to verify weather there's any big mistake or not ;;)....also plez ignore the anti aliasing and the shadow samples ( i kept them default for now ) .....below are my settings


Light settings ( light box )




GI settings


FG settings




a little comparison image



plezz give critics regarding this render ...it will be highly appreciated

[julius]

the GI+FG image is ok, and much better than the other one with GI only. If you want to increase luminosity, you can add a FG bounce : set diffuse to 1 or 2 max in the FG property panel. You can play with primary and secondary bounce color too (set it to 1.15 or 1.25 for exemple). You can increase photon intensity too....There's no rule, you have to test different settings, and see what is the best compromise quality/speed for your scene.

[agrmrs]

the GI+FG image is ok, and much better than the other one with GI only. If you want to increase luminosity, you can add a FG bounce : set diffuse to 1 or 2 max in the FG property panel. You can play with primary and secondary bounce color too (set it to 1.15 or 1.25 for exemple). You can increase photon intensity too....There's no rule, you have to test different settings, and see what is the best compromise quality/speed for your scene.

yeah that's it mate ...we can do it in few different ways ....... can i do tone mapping or is that an advanced feature ? it seemed very cool ....that's why i asked thanx