Question: Lightning-Types

[Oktavian]

More speed? Use shadow maps instead of raytrace shadows.

For generel introduction of different lighttypes search the max help, there is short overview.

[mouj]

Hey cANt, 3dbuzz has a nice vtm introducing Max's lights types and shadow maps, quite helpfull imho : )

check it here (http://sv2.3dbuzz.com/vbforum/uunr_vtmlist.php?c=2)

mouj

[JonasNoell]

Oktavian: Sure! But I was not referring to this point. I just liked to know whether there is and why there is such a huge amout of rendering speed between Target Spotlight and Target Directional Light applied both with Raytraced Shadows (Shadowmap doesn't work for me because it produces a large amount of bugs and even only renders about 10% of them)
mouj: Thanks a lot, I will definitely check it out for shure :thumbsup:

Greetings
cANt

[Marcel]

There are a number of things unfluencing the rendertime with raytraced shadows:

- polycount (duh :) )

- distance of the light to the target
The furtehr away the light is from the target the longer it will take to render, in some cases this can be a dramatic increase. (From 3 minutes to 15 minutes for example)

- the size of the hotspot/falloff
The bigger the falloff range the longer it renders.
So always try to bring your lights as close to your objects as possible. In your case I think the longer rendertimes are because the switch from target spot to a target direct light increased the falloff range a lot.

Another good tip is to use the 'overshoot' function. This will make the light shine everywhere, but it will only cast shadows in the falloff range. This is very nice for large scenes with shadowmaps, since you can use this to focus your shadowmaps on the subject.

To make things even more complex you can make a 'shadow only light':

Set your lights multiplier to 0
Set the shadow color to white
Set the density to -1 (or another negative number to have stronger or softer shadows)

Now your light doesn't cast light, but it does cast a shadow.
These can be very usefull for making localized shadows were needed.

[JonasNoell]

Marcel, man thanks a lot for all this detailled info this really helped me a lot, especiall the hint with the overshoot function ;) So the problem is that I have a quite detailled (many different objects) scene and must simulate a realistic looking sunlight. I first tried with Target Point Light, and the Rendertime is quite ok but the problem is that the light is emitted from a certain point and I need it come from a planar plane so that the shadows are symmetrical. But with Target Direction Light the whole thing needs about 20 minutes or so which is really long.

Another question. Is it possible to only render the shadows so that I can apply them later in Photoshop. So is there any way to make the shadows renderable while the geometry is hidden?

Help would be very helpful! ;)
cANt

[Dave Black]

One really good way to do sunlit outdoor scenes is to us light-tracer with a very low intensity as your fill light, and then use a spotlight as your key and shadow light. Just a thought. I've had really good results with that so far. render times can be kept down by dumping the samples down.

Also, your could try using area shadows.

As for rendering out just shadows, you can do so in the render dialog under the "render elements" rollout. It will just seperate them into a second frame buffer for you to save and play with.

Of course, all of this, accept the last point, is only available in R5.

Hope that helped a tad.

-3DZ

:D

[Dave Black]

This is just a simple light setup like I was talking about at the top of my last post. Don't know if is would help at all, or if the effect is what you are going for, but have a look:

[Dave Black]

Oh yeah, and one last thing:

If this is for a still, try this:

Turn off all your lights but one. Render it out. Repeat until you have a render of just each light affecting your subject.

Open PS. Create a new document. Open all your light renders. Copy and paste all of them into seperate layers in the new document. Set all but your key light to "screen" mode layer blending. Now, you can adjust the colors, intensities, etc. for each light without having to render a darn thing.

Just a thought. You probably already know that, but I sounds like you have a big scene and I just thought it could help.

-3DZ

:D

[JonasNoell]

Hey 3DZealot, thanks a lot for all your detailled information, I really appreciate this. Hmm unfortunately I "only" got Max 4 so I can't follow your first tip with the lightning setup even though the result in your second post looks great! What you mentioned in your last post was REALLY helpful for me and saves me a lot of time! Thanks a lot again :thumbsup:

[Marcel]

Another question. Is it possible to only render the shadows so that I can apply them later in Photoshop. So is there any way to make the shadows renderable while the geometry is hidden?

Yes, you can apply a 'shadow matte' material to your whole scene (save in a different file first) and set your background color to white. You might need to turn on 'receive shadows' in the shadow matte material. If you multiply this render over a render without shadow you'll have original result of rendering with shadows (hopefully :) ).

If you are using Max4 look up some tutorials/plugins on how to make a fake skylight with shadowmapped spotlights. If you want to do a nice sunlight simulation you will definitely need good ambient shadows.

[JonasNoell]

Thanks again a LOT for your very great help! :thumbsup:

[Marcel]

Just spreading the love around :)

By the way, your face texturing tutorial was very helpfull to me...

[CGTalk Moderation]

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.