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Daylight help
show user profile  mikegaynor
Hey guys, I have been working on a tutorial for making a photorealistic room from start to finish, but im having trouble getting the daylight to look right. Heres a picture:


The setup in 3ds max is:
1 MR Spot acting as sun shining in window, with a mult of 1 and hotbean of 24
3 MR Area omni's: one where the sun hits the ground, one under the picture and one on the ceiling all set on inverse square falloff and ambient only. The color of the ceiling one is the average color of the walls after the other lights hit.
1 skylight outside with 3 sky portals (one for each window)
Final Gather is just at 1 but I have 5 bounces set.
The outside atmosphere is just a white glow with the glare camera effect added.

I'm pretty new to architectural rendering so this has been a lot of trial and error to get this far. What can I do to make the window less bright but the room itself more bright or whatever would make it look better.
read 549 times
9/25/2011 1:47:46 AM (last edit: 9/25/2011 1:47:46 AM)
show user profile  mike_renouf
Since you're using mental ray then the whole method you've used begs one big question:

WHY?!

Mentalray has a dedicated daylight system built in. You don't need to fake anything with spotlights here and omnis there. Delete all you existing lights, place one "Daylight System" into your scene, enable mr sky environment (usually max will prompt you to do this) and enable photographic exposure (again, you should get a prompt).

From that point its just a rendering exercise.




read 534 times
9/25/2011 8:18:24 AM (last edit: 9/25/2011 8:18:24 AM)
show user profile  mikegaynor
I did that originally, what should I do to make scenery outdoors then? Or should I blow out the windows with the photographic exposure?
read 522 times
9/25/2011 7:24:20 PM (last edit: 9/25/2011 7:24:20 PM)
show user profile  Nik Clark
Indeed. You should be able to get it exactly as you need with just the daylight system. Looking at the Wikipedia page on mental ray, there's a great example of just the daylight system being used in a room with glare, etc.



read 517 times
9/25/2011 7:35:51 PM (last edit: 9/25/2011 7:36:32 PM)
show user profile  mike_renouf
http://www.maxforums.org/threads/antialiasing_issue/0001.aspx

The link above is a recent thread about a scene of mine which is just like yours. All lit by daylight alone. You need to learn about mentalray sky portals too. They're a bit resource hungry but they'll give you the results you're after.




read 503 times
9/25/2011 9:09:41 PM (last edit: 9/25/2011 9:10:39 PM)
show user profile  mikegaynor
Thanks for the responses. I've used daylight before and I have 3 portals in the scene already. I got the system I have from a similar one on cgarchitect.com.

After playing with the exposure control a bit more I am getting decent results, but I still don't know what my environment settings should be. Mr physical sky gives the blue sky color, and white glow gives the blown out look of the windows, but if I actually wanted like a tree and some clouds would it be better for me to actually model those things or to use a bitmap on a plane or something?
read 488 times
9/26/2011 1:15:13 AM (last edit: 9/26/2011 1:15:13 AM)
show user profile  mike_renouf
Modelling the exterior is probably overkill. The method I tried a few times is to put an hdri image into the environment map slot instead of the mr physical sky. This works from a technical standpoint, I just never had any decent hdri images which suited my purpose and since a great deal of my work is purely as a hobby I've not laid out any cash for proper ones.

The only thing you need to watch is that you set the "RGB Level" parameter correctly in the "Output" section of the map in order to get it the right brightness to synch the light level with your scene setup.

The other challenge that then comes from using a background image is of course matching perspective and camera angle.

I dare say that you could use a standard bitmap image (e.g. a jpeg or a tiff) instead of an hdri, but I don't know how this would need to be altered to get the light levels right.

If none of this appeals then you could always go into photoshop afterwards and add something manually - this can work okay too, but obviously if you're re-rendering later for any reason you're stuck with repeating that bit of postprocessing.

Hope this helps - it'd be good to see an updated scene when you get a chance :)




read 466 times
9/26/2011 8:57:49 AM (last edit: 9/26/2011 8:57:49 AM)
show user profile  mikegaynor
Thanks =] I have a few hdri's i'll see if some of them will work out and ill post an updated image soon
read 453 times
9/26/2011 7:29:56 PM (last edit: 9/26/2011 7:29:56 PM)
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