Help with Lighting an Interior Scene.

[Jackdeth]

Check your overall scale of the scene. To have the GI energy at such a low value seems really wrong from all of my expierence. The numbers are usually 100,000 or much higher. Perhaps your scene is tiny, and therfore the lighting is behaving in a bad way.

We set the units to centimeters and then say each grid unit equals 1 foot in real life. This scale seems to work great, and I know lots of other studios use the same setup.

Also, dont use diectional lights with GI photon emitting if you have a FG sky sphere. The sphere might be stopping the photons from even reaching your scene. The manual recommends using a spot light because you can focus it only where you want the photos to be, and control where they came from..

[:zepedro:]

Hello

I´ve downloaded your scene to try sorting things out, but it has no lights, only geometry. If you could post the same scene that you´re rendering, i will try help you with the settings on materials (even if only 1 white material), lights and render globals.
In the meantime i´ve noticed that your scene is like 8 times larger then mine, take a look at my settings and scene measures in the sreenshot, i can´t tell very well what is the relation between scene scale and the lighting, i try to use a scale (more or less) related to real world, 7*8 meters in this case ( i´m sorry for using the metric system, i´m from portugal :) )
Oh, and i´m using my light with a linear decay, it´s a big difference in the numbers of intensity between the different decays.
Try setting the Irradiance Color of the materials (mental ray tab) to 0.3/0.4 instead 1, i´ve noticed that fg behaved more naturally with this settings, althoug you have to raise the intensity of light and Gi energy to obtain the same lighting as before.
Is a long trial and error process, don´t despair ;) , i´m sure we can pull nice results from mentalray for maya, with more or less documentation, tricky settings or louzy connections between software´s.
There are many usefull threads you can read for learning from other users discoverys, and trials.
Can you post a image of your results also, to see the problems you´re talking.

Thank´s


http://threed.no.sapo.pt/images/SCREEN_MEASURES_SCENE.gif

[Tierackk]

Hey Jackdeth thanks for your reply :thumbsup: That makes total sense and would explain why when I have a higher energy level everything turns white, but the thing is the scene is set in centimeters. and the height of the room is 21 grid squares, meaning it would be equal to 21 feet in life. High celings but then I guess the scene is of a decent scale. ?
The lighting set up I've been using is 1 spotlight with the rectangle area light turned on. For extra energy and phontons I would use 1-2 pointlights with no intensity.



Hey :zepedro: thanks for your reply :applause: . I happy to see you responded considering you would know alot about this room:p. I didnt put any lights or materials because I figured it might be better to start fresh, but your right I'll post my scene with lights and just white in a little while. In the meantime I will try with the scene converted to meters and with your other advice. It's weird that the scene would be larger for you because I modeled it in centimeters and if you working in meters then it should be smaller no?:shrug: I dont mind meters thoiugh we use them here too(well somtimes).

[lazzhar]

Here is my tests on your scene. As usual I didnt render in one pass. First I started byt setting a simple lighting with a Spot key and a Point fill light.Then set the key as a photon emitter. After tweaking a little bit i have connected a DirtMap to the diffuse attribute of all shaders in the scene(usualy i render an extra pass of the scene with a surface shader tha has a DirtMap as an output color and assign this shader to each object) Here is the results:

http://lazzhar.arabcg.com/oldimages/roomdl.jpg
http://lazzhar.arabcg.com/oldimages/roomgiao.jpg

But as you could see there is no light hitting the ceiling coming from the windows. So I planed to get that by adding an area light outside. but I instead i prefered using Final gathering for that, how? just add a big plan and set its matterial to a white surface shader and inctrease the "V" value when choosing its color to something high( i used 7).
http://lazzhar.arabcg.com/oldimages/roomfg.jpg


After that, the rest is done in Photoshop by putting the last picture on the first with a screen mode(i have photoshop 5.5), adding some Glow effect and have a fun:
http://lazzhar.arabcg.com/oldimages/room.jpg

Here is the 2 files of GI & FG compressed with WinRAR(150 k) :

http://lazzhar.arabcg.com/oldimages/room.rar

You could tweak as friends said here, but I prefer this way.

Hope this helps.

-lazhar

[Tierackk]

Wow lazzhar!

Thanks for your help!. Its great to see different approaches to a scene with different minds. I didnt realize that you had comped 2 renders (FG and GI) togeather. I wasent thinking outside the box:blush: See this is the situation where I get confused. You use pretty low GI photons, low energy, and you dont use the area light for the spot light, yet you get great results(in a small amount of time!). I guess this approach is better for 'soft lighting'!? :shrug: Again thank you, I'll be setting up many rooms and applying/learning your technique.:bowdown:

Then there is the flipside when energy levels are at 100,000, photons up to 1 million, extra lights emitting photons. I guess this approach is to achieve results simliar to zepedro and i-d.

Well zepedro, this is a file with a setup similar to yours. The shader is conntected to a DGS material and the diffuse is set to the dirtmap. I think I am beginning to realize that my problems could be coming from the materials and not so much the lighting. I think it could be the DGS material. I was under the impression that the DGS will give you a more realistic absorbsion and distribution of photons(along with quicker render times) and the colour is set by the diffuse channel in the DGS. I have it linked to all the lights in the scene, but I think its making the scene more difficult to light. If you render it now it looks like..well like nothing.



Scene in Meters (http://www3.sympatico.ca/triyasat/room_in_meters.zip)

[sebast1an2]

:applause: wow, nice scene lazzhar... here is an rendering from a different viewangle:

http://www.strategic-air-command.com/weapons/images/nuke-home-blast.jpg


:applause:

[lazzhar]

sebast1an2, it would be nice if someone can see your work ;)

[brunner]

Sebastian, check out my latest render:
(i STILL can't get rid of the nuclear blast :( )

http://pro.corbis.com/images/watermark/67/14152872/O-066-0364.jpg

[wgreenlee1]

heres one i messed with fer a few minutes today....non-nuclear blast windows included

[tumbi]

yep
another nuclear render :p

[Jackdeth]

Mental ray doesn't suck, it takes skill and expierence to make it work.

Dont knock it if you can't cut it.

[tumbi]

ok
i dont undestand Mental
but where is images like this rendert with MentalRay?
http://www.vrayrender.com/gallery/?type=1

[lazzhar]

Hey nice rendering brunner :)
I still cannot deal too with the nuke in my scene here:
http://www.alshoq.com/~kdesign/2.jpg
and this:
http://www.alshoq.com/~kdesign/1.jpg
Noway :(

[playmesumch00ns]

Originally posted by tumbi
ok
i dont undestand Mental
but where is images like this rendert with MentalRay?
http://www.vrayrender.com/gallery/?type=1

Erm, on the cinema screen?
Film (http://www.mentalimages.com/4_1_motion_pictures/index.html)


As jackdeth said, it's a tool. Don't knock it just cos just don't properly understan how to use it.

[tumbi]

okay :beer:

[lazzhar]

You could see a lot of architectual visualisation renderings because peoples were using VIz and Max for years in this field, and now when came VRay and Brazil and Final Render users switched to this new renderer.
Mental Ray was one of the first renderers that has implemented Global illumination technique, However because it was just used fist with Softimage 3D and XSI you could not see a lot of pictures of visualisations.
the reason is that Mental Ray is rather used in Cinema and Animation. We dont need to talk about using Mr in Matrix reloaded and many animations by ILM.
But if you want to see very nice rendering go to the gallery in Softimage.com
MR for Maya is a new tool, and a question of time to see works like you see in VRay galleries.

[AniMo]

hehe this time sebastian realy made me laugh some minutes :D

[lazzhar]

Hi
Here is a rendering with nuclear blast unchecked in render global ;)
http://lazzhar.jeeran.com/salons01.jpg

[brunner]

This time you checked the "miniature" option :)
the pronounced DOF makes it look much smaller.
LESS DOF:)

[lazzhar]

Ooops, i checked also that button ! but I like this 'miniature' look too :)

[lazzhar]

Sebastian, I ve forgotten to show you a bad picture rendered by a bad lighter called Jeremy Birn working for a bad company called Pixar producing bad Movies like Toy Story and Finding Nemo:
http://lazzhar.jeeran.com/jb.jpg

And here is the video:
http://www.3drender.com/light/bluedoor.mov

PS: Sorry Jeremy :rolleyes:

[JasonA]

This might sound like a dumb question, but I'm wondering what this "dirtmap" is that you guys keep referring to? Is this some sort of procedural texture in maya 5 or ...

sounds interesting and I'd like to know more about it. Hopefully its something I can do in maya 4.5
:)

[Jackdeth]

Its a raytrace amibent occlusion (sp?) texture node that basially finds where objects are close together and darkens that area. Its like a soft shadow shader that can be used fake shadows from an FG sphere around the scene. It was created to fake GI and FG back in the day...

In these room tests the guys are using it to find the coners of the room, and generate soft shadows there to add realism. Or put it on a spaceship and cool dark shadows appear between every little panel and antenna on the ship.

Its really cool, but easy to over use.

[brunner]

guess the only way to avoid the "nuclear blast" (in Maya) is to composite the render(photoshop or whatever)...for now
No, not really. It may be the easiest, the fastest, but it's not the only one.

has used the dirtmap to its full potential. His classroom render has great natural corners
:blush:
uhm, that was just a joke and an attempt to make fun of sebastian :)
It's a bloody picture. You can see CORBIS written all over it :D

[lazzhar]

Thanks Tierackk, you've really gone away, but thanks anyway.
I just wish to say the I didnt use FG at all in this scene. For the light coming from outside creating that soft shadows I just used 4 spot lights for each window casting depth mapped shadows. It's faster than using area lights or FG. And of course I composed all in Photoshop. I could render all in one time but I prefer separate passes for easy and fast tweaking.
BTW, if you dont have "Digital Lighting & Rendering" from Jeremy Birn, get it, you'll not be dispointed at all.

[P_T]

i was just wondering... does anyone here ever tried faking the GI? i saw some MAX faking GI render tutorials in CGarchitect site. They don't look physically correct obviously but still damn good (if u're not a physics freak that is :p).

i tried to open a thread about it before but noone seems to be interested. :shrug:

[Jackdeth]

You can fake it. Depending on you scene (this is something that we are doing right now for a film), you can add an array of spot/directional lights around your scene to fake a sky dome. You have to use at least 4 (usually you have 8-10), and they have to have REALLY soft shadows so they don't feel like obvious directoinal lights, selling the trick that a sky light comes from all directions. Also, turn off specular so that you dont get crazy highlights all over the scene. We are then also using some SSS to create light bleeds and softness in the scene.

This is being done only because FG looks good, but with hundreds of spinning and falling objects the FG flickers like a bastard. And to stop flickering the render times go over 8 hours a frame on dual 3.2ghz zeon. It hurts.

but then again, this cheat works great here, but maybe not for some interior scene. But the trick is to remember that YEARS and YEARS ago people we doing amazing lighting with no GI, FG, raytracing, etc, etc...

This is all about the skills of the artist, not the simple buttons that he/she can push.

[lazzhar]

Faking GI is a pain. I've tryed lately with this scene:
http://lazzzhar.jeeran.com/salle01.jpg

I used raytraced shadows from the light representing the sun, but the rest is spot lights with depth map shadows. I added a slight layer of Ambient occlusion(with DirtMap) just to draw some edges. You could see here the rendered picture and a screen shot of the Maya scene and the setup of lights:
http://lazzzhar.jeeran.com/salle01lfr.jpg

http://lazzzhar.jeeran.com/salle01wire.gif

[JasonA]

hey that loks pretty good actually.

I think lighting the 'old fashioned' way is still a better skill only because computing power is just not there to be able to use GI of FG in really complicated scenes. I can't wait hours upon hours to render one frame of a 10k face scene (which is piddly sized even). Course I can't talk cause I'm running on a p3 850.

jackdeth, thanks for letting me know waht dirtmap is:) I might give it a try if I can get it setup correctly.

[Jackdeth]

10 polys? that must be nice. I gotta get 25 million polys to render over 4000 frames.....I'm pulling out every cheat I can....and now its gonna look great....

You guys are lucky only worrying about an interior room...

[P_T]

Originally posted by Jackdeth
10 polys? that must be nice. I gotta get 25 million polys to render over 4000 frames.....I'm pulling out every cheat I can....and now its gonna look great....

You guys are lucky only worrying about an interior room...

well BOO friggin HOO... u're getting paid for it lol :p

[JasonA]

Originally posted by Jackdeth
10 polys? that must be nice. I gotta get 25 million polys to render over 4000 frames.....I'm pulling out every cheat I can....and now its gonna look great....

You guys are lucky only worrying about an interior room...

well 10,000 faces actually... course on the scale of 25 million, I guess that makes little difference :)

seriously though, most of my scenes are around 500,000 faces.. and on one computer, GI or FI means my computer is rendering for days for one frame.... totally impractical.

[Jackdeth]

Yea, thats really tough on one machine. Well, best of luck to ya.:beer:

[vrf]

Originally posted by brunner
This time you checked the "miniature" option :)
the pronounced DOF makes it look much smaller.
LESS DOF:)

Not to be too picky, but "less depth of field" would only blur out more of the scene. The render needs more (deeper) depth of field, meaning more areas in front and behind the "point" of focus appear sharp and in focus.

[johnnynightlife]

i downloaded the second scene file with DGS, and Dirt, created 2 spotlights, one outside each window, and one point light inside. the two spotlights i set energy to 300000, and the pointlight i set to 200000, but the scene was just barely lit, am i being to stingy with the energy?

[brunner]

Originally posted by vrf
Not to be too picky, but "less depth of field" would only blur out more of the scene. The render needs more (deeper) depth of field, meaning more areas in front and behind the "point" of focus appear sharp and in focus.
You're right ;)
My tendency to simplify things can lead to quite wrong phrasing sometimes :)

[Jackdeth]

The energy settings can go really really high.
Push it father than you would ever think possible and that still might not be enough....

[Tierackk]

Ive been getting half decent results now with lighting this room.. im just trying to figure out why some renders(zepedro) have combined energy values of close to 1 million. I understand the scale of the scene will contribute to this factor but even still when I try different scene scales it still seems to wash out (especially if its being rendered with FG at the same time). I guess the DGS must be responsible because energy needs to be increased when the DGS is applied. This is a recent render..still lacking realism. low energy and a total of 50,000 photons render simultaneously with FG, no source.



http://www3.sympatico.ca/triyasat/rOom.jpeg

[lazzhar]

Very nice rendering.
Good luck.

[Tierackk]

Thanks lazzhar and thanks for your help.:beer:

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