improving interior lit mostly by indirect

[Ernest Burden III]

Sorry to keep throwing up questions, but so far I am not getting the results I need to out of C4D.

 

I was up till a very late hour playing with rendering settings and trying to get an acceptable result from C4D.

 

This is an early version of a model I'm rendering from both outside and one interior. I did the view studies in Lightscape, and now I want to use C4D for finals. I have matched the camera and sun angles.

 

So far I have tried all sorts of radiosity settings, put in a sky object with both a color and an image map...

 

By the way, the sky object with a lum. channel lights the scene but does not appear to cast shadows. Does that only happen with an HDRI image?

 

The only way to get very much light to show in the interior is to use a rad. strength of 800+ ... or is it?

 

It seems like C4D requires using 'ambient' light to get much into shadows, which is a cheat anyway. I'm thinking of putting up some billboards to bounce some light back into the scene. I do not want to get into placing faker-lights everywhere and light-rigs etc. to overcome this. I hope it isn't necessary!

 

Any suggestions?

[STRAT]

By the way, the sky object with a lum. channel lights the scene but does not appear to cast shadows. Does that only happen with an HDRI image?

it does cast gi shadowing, you probably need to up the accuracy. HDRI??? no. hdri is pointless for image based lighting. i hardly ever touch it. no need. plain old bitmaps or plain color will do nicely.

 

 

The only way to get very much light to show in the interior is to use a rad. strength of 800+ ... or is it?

 

nooooooooooooo. try not to ever go above 100% else it looks fake, and eliminates normal gi shadows in most cases. for internal lighting use the normal attenuated omnis where the design predicts.

 

if there is no omnis in the design well you can either up the illumination channel's value, or up the diffuse depth. personally, i put in literally 1 or 2 low light emmiting omnis as fill lights. as you say, sounds cheating, but does the trick.

 

 

to get more out of shadow work up the accuracy level. for finals i always use 100% accuracy.

 

look at these to images i just knocked up -

 

image 1 is basically 4 simple primatives, lit only by 1 omni acting as the sun, and a sky object with some light blue colour in the illum channel set to 100%

 

 

 

 

image 2 is exactly the same, but i've erased the omni light and the whole image it lit entirely by the sky object -

 

 

 

if you want i can give you this c4d file to study.

 

dont be afraid of inserting 1 or 2 omnis as fill lights. (dont use the standard ambient lighting tho) this is quite acceptable in all gi renderers as it's much faster than upping the bounce light levels, and just as effective.

 

another method of internal lighting is to add an 'invisible' object/primative into the centre of the room emmitting an illuminating gi effect.

 

 

 

 

 

[Ernest Burden III]

nooooooooooooo.

 

Thank you, as usual, for the advice.

 

I started with your suggested settings (printed out, sits by the 'puter). At 100% GI, the scene is mostly black. Remember--the Lightscape sample is just the sun and about 10 mins of processing and 15 seconds of raytrace--the C4D is over an hour, and still dark.

 

The sample is set at 250% GI, uses your sky object idea, diffuse to 2.

 

Even if I can up the sun brightness, or the recive GI %, the result is blowing out the exterior. Sure I can use different setting for each, but one reason I am trying to use C4D for this project is that Lightscape has trouble balancing outdoor illumination with indoor.

 

I'll get it in the end...

 

 

You know, I forgot to play with the min-max settings, I wonder if that will help this out?

[STRAT]

do you want to e-mail me the basic c4d model and i'll play with it for 5 mins or so and send it to you back with some lighting set up in it?

[Ernest Burden III]

do you want to e-mail me the basic c4d model and i'll play with it for 5 mins or so and send it to you back with some lighting set up in it?

 

I appreciate your generosity. I sent it to the hotmail account...

[STRAT]

hi Ernest, sorry to be a pain, but could you send it to my works addy too pls?

 

steve.leworthy@holdermathias.com

[Ernest Burden III]

hi Ernest, sorry to be a pain, but could you send it to my works addy too pls?

 

That's not being a pain! That's being a VNG (very nice guy).

[STRAT]

sorry about the delay, only i got 3 other jobs to get on with too

 

ok, here be a small test.

 

image 1 -

 

 

this is lit with a plain blue gi sky object with high illumination settings in the material editor (about 400). and you can see the other render settings in the box.

 

i also lit the internal area up with an invisible plain casting gi light, hense the massive gi samples (800).

 

render time about 6 mins.

 

 

image 2 -

 

 

this was rendered with the standard sun you put in and 3 attenuated infills at 30% each. samples were lower and render times was 4 mins. the general shadow depth in this example can also be nicely controled by the infill shadow controls.

 

please note these images are simulating daylight bouncing within the room. no illuminaires are switched on in the room.

 

 

with a little tweeking and optomising you could easily knock off another minute or 2 render time whilst also upping the sample quality. i use 100% accuracy, but this is not essential. 85% would easily speed up matters. not also that a diffuse depth of 1 was used and the radiosity strength is set at 100%

 

do you want the c4d file of the second image email to you EBII?

[Ernest Burden III]

do you want the c4d file of the second image email to you EBII?

 

Sure, and thank you for the help.

ebiii@oreally.com

 

Why can't we just merge Lightscape into C4D?

[STRAT]

okie-doke, just emailed. if you dont get it tell me and ill send it differently again

 

Well, i've never ever used LS in my life before, but ironically it's my fav radiosity renderer. i so wish it was still in production and i had a chance to use it.

[STRAT]

lol, just noticed i keed calling you EBII. oops

 

i pressume then ur father and grandfathers were EB's too?

[Ernest Burden III]

lol, just noticed i keed calling you EBII. oops

 

i pressume then ur father and grandfathers were EB's too?

 

That's right! And my sons are Kyle and Luke. Enough is enough.

[jackb602]

Ernest,

 

I've had the same problems lighting interior/exterior scenes exclusively with natural light (i.e. sun & sky). One trick I've found that works quite well is to adjust the Gamma setting in the Color Correction post effect. It works just like Photoshop's gamma control. Using it as a C4D post effect gives better results than Photoshop. With the right settings, you can brighten your interior without blowing out the exterior lighting. Hope this helps,

 

Jack