rendering large scenes, very large scenes

[guyhaviv]

Hi

 

Does anybody know how do i light up a large scale scence (say: a whole neighbourhood ), the problem is with the shadows.

If i use shadow map i get the pixels of the shadows cause the area i try to light is very large, ray trace shadows is not an option, I'll use ray trace only for spesific objects.

So, how to shadow map a large area ?

 

thx

 

Guy

[STRAT]

first off use a DIRECTED light. the beam is much more defined and focused this way.

 

second, dont place the light source too far away from the scene else you loose more and more shadow defanition.

 

third, set a low bias, a shad map size as large as your pc/ram will let you, and a fairly sizable sample range - maybe 15-20+.

 

you'll have to play.

 

imho max's soft shadows are an extremely poor excuse for shadows. extremely poor, especially compaired to their piers on the market. i hate them.

[Jennifer]

Hi,

 

Direct lights produce a cylinder of light, rather than a cone of light as a spotlight does. This give a closer approximation of a distant light source, such as the sun, where the light is coming at you in parallel rays.

 

Distance from the scene doesn't matter with the Direct light, and won't affect the shadows. The Spotlight becomes more parallel as it gets farther away.

 

The size of the Falloff determines how spreadout the shadow map is. If you have memory issues you can turn on Overshoot to light the entire scene, and set the Falloff just to the area that you need shadows cast.

 

If you have multiple lights, setting the Ranges can help considerably with rendering speed, as max does not need to consider the lighting beyond where you need it. You may be able to turn off shadow casting for some lights. Turning off shadow casting for objects that don't need to cast shadows can help with speed, for instance, if the back of the building has a shadow, but you never see it.

 

Increasing the sample range can help to blend the edges of the shadows, reducing the blockiness. Decreasing the Bias moves the shadows back towards the objects, and for exterior scenes this is usually needed, I've found. Otherwise small shadows under trim, etc, don't show where they should.

 

Have fun!

 

Jenni

[STRAT]

dont forget to play with increasing the DENSITY too. most ppl ignore this setting but can dramitally add form and shape to otherwise wishy-washy shadows.