PDA

View Full Version : Lighting Question


catizone
01-30-2008, 01:38 AM
Forgive my ignorance on lighting and surfacing in messiah. Just two areas that I never used the program for.

I have been thru the docs..and probably missed it (I hope).

BUT...how do I prevent a surface from being affected by a particular light? How can I adjust the density and color of the shadow...without rendering the shadow as a separate pass and comping?

Thanks in advance.

Best,
Rick

Ulven
01-30-2008, 02:15 AM
No shame in asking, I'm not much of an expert on this side of the program either but I'll answer what I can. Perhaps someone else can fill in.

First of all, to turn off a light from a surface, go to the render -> surfaces tab. Click the Surface name in the list (this is listed under the object it belongs to, then the material that is applied to that surface is listed next.) Then click the lights tab and click the grey ball next to it. I don't actually know what the black one does.

As far as I know there's not a control to set shadow colour and density as it were. Principally, the shadow will take colour and density more from other lights, such as GI bouncing. The softness of the edge will depend on the diameter of the light if it is a sphere light or disk width/height if it's a spot light.

catizone
01-30-2008, 10:20 AM
Thanks Ulven!

Some of my question actually relates to some lighting I am doing for my last Masters coursework, and I thought I'd use messiah and actually try and learn that side, as opposed to LW, which I am more familair with for that issue. The EXTRA challenge and all that.

Anyway, for this particular start, I have to replicate real world light on a miniature setup of foamcore walls and and a sphere and other prop. And I cannot use global illumination, as the point of this particular exercise, which I'm sure you are familiar with, is to use appropriate key, fill, and other bounce lights to mimic the lighting scheme.

Yes, the GI solution in messiah is very nice as attested to by the great look on Andy's Airplanes. I may be able to use that for other work, but I think most of it will be ACTUALLY lighting the various environs.

(I miss our semi-daily conversations when we were in production.)

Thanks again,
Rick

Ulven
01-30-2008, 01:54 PM
In that case, I would use other normal lights to set up the various colour and density of the shadows. I.E. old school techniques such as for instance the sky being represented by a large blue light, lighting the scene from above. Bounce light being lights under the floor for instance, with the colour of the floor, and a nice falloff. I think the floor may have to be a seperate object to not cast shadows. Good luck Rick. Post a wip and we can help you crit.

catizone
01-30-2008, 02:15 PM
Yeah...that's the approach I am taking....I had the walls and floor as one object...thinking I could control by surface....so thanks, I'll separate them and try and that.

Best,
Rick

rago
01-31-2008, 02:15 PM
Then click the lights tab and click the grey ball next to it. I don't actually know what the black one does.

I believe the black one is for the specular part of the light, and the grey for difusion.
If you're lighting the old way you should keep sets for you're diffuse light separated from the ones used for your specular highlights.
Both these aspects are in the light comand usually preset at 1.0 value.

I have a question as well, is there any material node that would work as a shadow catcher, so that the actual material so to do a direct shadow pass?

catizone
01-31-2008, 02:30 PM
Yes, that's for Specular...you can see a tiny highlight on that sphere. I eventually found that part of the docs after Ulven pointed me in the right part of the surfacing tabs. I knew it was in there, but I seemed to be turning off the scene lights instead of the diffuse and spec channels of a particular surface.

Any object you want to see a shadow on, set to Unseen By Camera, but Receive Shadows. (Hide any objects that won't be casting shadows or receiving them.) Any object casting a shadow, you want to set to Unseen By Camera, but Cast Shadows. Then in the Render tab, select the Shadow Buffer, and set your output path for the images.

Best,
Rick

catizone
02-03-2008, 11:47 PM
I haven't found anything in the docs yet, but do we have a way to see the actual Falloff parameter via an additional ellipse or such?

It would be nice to be able to set a falloff, and also view the range of the effect, as one can do in 3D MAx for example.

Best,
Rick

kursad_pileksuz
02-04-2008, 01:20 AM
there is not a way to see the fall off. But you can create simple expression based on light falloff size that drives a procedural sphere`s size to compansate lack of visual falloff.

catizone
02-04-2008, 02:28 AM
wow...there's something that never occured to me....

I hope tha PMG adds an indicator. While I use messiah for production work, I teach a bit of 3D Max. Messiah is so advanced, sems like we really out to have that...as well as a shadow density and color parameter control.

Thanks again,
Rick

rago
02-04-2008, 02:15 PM
Any object you want to see a shadow on, set to Unseen By Camera, but Receive Shadows. (Hide any objects that won't be casting shadows or receiving them.) Any object casting a shadow, you want to set to Unseen By Camera, but Cast Shadows. Then in the Render tab, select the Shadow Buffer, and set your output path for the images.

Are you shure that it works, and what file format would it be more convinient to use?
I tried casting a shadow without the object being seen, and it works, but when I want to see a shadow cast by another object on a surface that is not seen from camera I only get background color where the object should lie, but no shadow.
The shadow buffer seems to change nothing over the regular color one.

kursad_pileksuz
02-04-2008, 03:00 PM
There has been alot alot of fixes and additions to the render engine. This may may been fixed in the coming update.

CGTalk Moderation
02-04-2008, 03:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.