soft shadow

[jakerupert]

After achieving a bluish shadow I am trying to reach softer shadows here.

 

went from default sampling of the sunshadow to 3 and bias to 10

but no big difference...

[robcat2075]

For ray traced lights you'll need to make the size (width?) parameter larger. The light's position is jittered for each sample and if it's very small the position isn't different enough to make the shadows fuzzy.

[jakerupert]

I altered the defaultsize from 10 to 1000 and to 500 with 5 passes,

but am still very far away from the nice shadow Stian does achieve with his Tramtrainpicture...

Any ideas?

[robcat2075]

In Stian's pics he has a fairly sharp primary shadow and the AO is what's doing the haziness within the primary shadow.

[R Reynolds]

I get soft shadows that I find convincing with klieg "sun's" whose diameters are about 200 ft. and 3.5 miles away from the characters.

[jakerupert]

Well, I will test both this with the fakeAO as soon as can.

 

Do Kliegs suns also work with fakeAO or am I limited to raytrace suns?

[jakerupert]

Still fiddeling around with things here.

 

I rendered the scene with AO and see no big difference though (suns set back to defaultsize 10)

 

Also in this scene: bluecolor on train and the rocks at tunnel =matcap shaders, grass = colormap : 50 % and displacementmap : 1000%,

gravel on track= normalmap, landscape as a whole= with fakerimlight mat,

 

especially the lighting is not what I want yet. I also don`t understand, where Stian gets the huge rendertimes from.

This picture renders 16 min with AO on and 5 passes on a fairly old computer.

[robcat2075]

I don't think Stian sets his shadow color to blue. I think it's the fill that is adding blue to the dark shadows.

[jakerupert]

Thatt`s the way he does it (See his Tramtrain-thread):

 

 

First, here is a basic AO with one sun setup. Kind of grey and boring

 

Reduced 17%

 

320 x 240 (18.7k)

 

 

On a sunny day, take a look outside, the shadows are actually not grey/black, but blueish

 

 

So to accomplish this, here is a trick that I learned from rodger_r:

First, In addition to your main slightly yellow sun, add a second sun with the same settings at the same position, but with a blue color and Cast Shadows to OFF. This will give you an overall blue tint to your image including blue shadows. But since the sun should give you a yellow tint to your image you add a third sun with exact same settings and position as your second sun, but with negative intensity and Cast Shadows to ON. The third sun will override the blue tint from the second sun but keep its blue shadow.

 

Reduced 17%

 

320 x 240 (20.6k)

 

 

 

Just for fun. This is how the render looks like if you turn off the main sun

 

Reduced 17%

 

320 x 240 (28.68k)

[NancyGormezano]

Do Kliegs suns also work with fakeAO or am I limited to raytrace suns?

 

Yes FakeAO works with kliegs. I have only tested with Kliegs that have z buffered shadows, where you can set the shadow color AND color of light. see here. I have not tryed fakeAO with kliegs that use ray trace shadows, where you cannot set the shadow color, you can only set color of light. I have no reason to believe FastAO wouldn't work with ray traced kliegs.

 

I also don`t understand, where Stian gets the huge rendertimes from.

This picture renders 16 min with AO on and 5 passes on a fairly old computer.

 

Stian usually has a gababillionzillion patches in his models. Usually that means longer render times with AO. Your models look less dense patch wise. And using sun's with ray traced shadows is a render time hit as well (that's why Kliegs with z buff shadows are preferable if you can)

 

Interestingly enough, FastAO looks better when there are more patches in scene/model. Low density patch models don't show the effect as much. The number of patches is not as big a rendering hit in FastAO as in real AO.

[NancyGormezano]

I get soft shadows that I find convincing with klieg "sun's" whose diameters are about 200 ft. and 3.5 miles away from the characters.

 

Are you using kliegs with z buffered shadows or ray traced shadows?

 

If kliegs with z buffered shadows - do you have "black" as shadow color? (shadow softness?, darkness?)

 

If they are kliegs with ray traced shadows, why wouldn't you use sun type lights instead?

[R Reynolds]

Do Kliegs suns also work with fakeAO or am I limited to raytrace suns?

I always use at least 2 rays per sun. Raytracing ensures (referring to the earlier render I attached of an old building) the shadows from the handrail falling on the nearby wall are sharper than those cast by the building's corner on the more distant garage wall.

 

If they are kliegs with ray traced shadows, why wouldn't you use sun type lights instead?

The last time I tried them, suns don't produce controllable soft shadows with ray tracing. I only use sun type lights (eight of them with no shadows) arrayed around my sky dome's perimeter to simulate bounce light from the ground to help fill in the shadows under overhanging roofs. See attached images.

 

I should also set the record straight that Yves Poissant is the originator of the negative blue sun shadow technique and kindly shared.

[animas3D]

Hello,

 

Nice models all around.

 

So in order to get your soft shadows, Rodger, you are basically using a klieg (spot light) as your main source of shadow casting light, then setting the softness of the cone to zero (in other words, the inner cone doesn't exist so the whole cone is soft?), you're putting it really far away from the model you wish to light, you're increasing it's diameter and you are setting the rays cast in the shadow to be 2 or more.

 

And this is how you are achieving those nice soft shadows all around. Correct?

[R Reynolds]

...this is how you are achieving those nice soft shadows...

That's correct.

 

My first objective was to put the sun as far away "as possible" from the characters such that in really high, long shots it's not obvious that the shadows are not all as parallel as they are here on Earth. Three miles seemed reasonable.

 

The second objective was to pick a sun diameter that produced convincing soft shadows. To calibrate this I took my camera, a ruler, a protractor and a sheet of white cardboard and found a flag pole with no flag flying on a sunny day. Using the angle of the shadow and it's length I estimated the flagpole's height then took a picture of the shadow it's top cast on the cardboard with the ruler lying in the shadow's transition from full sun to full shade. Armed with this known shadow I modeled the flagpole and a ruler in A:M and rendered images of the shadow on the ruler with different sun diameters. 2500 inches produced a similar looking transition. It's all crude, back-of-the-envelope calculations and personal judgment, but then again I'm the final customer.

[John Bigboote]

Wow. Back of the envelope calculations... awesome. Beats my 'eyeball and fudge' approach.

[R Reynolds]

"The Eyeball and Fudge"

 

Great name for a pub.

[animas3D]

My first objective was to put the sun as far away "as possible" from the characters such that in really high, long shots it's not obvious that the shadows are not all as parallel as they are here on Earth. Three miles seemed reasonable.

That makes sense.

 

The second objective was to pick a sun diameter that produced convincing soft shadows. To calibrate this I took my camera, a ruler, a protractor and a sheet of white cardboard and found a flag pole with no flag flying on a sunny day. Using the angle of the shadow and it's length I estimated the flagpole's height then took a picture of the shadow it's top cast on the cardboard with the ruler lying in the shadow's transition from full sun to full shade. Armed with this known shadow I modeled the flagpole and a ruler in A:M and rendered images of the shadow on the ruler with different sun diameters. 2500 inches produced a similar looking transition. It's all crude, back-of-the-envelope calculations and personal judgment, but then again I'm the final customer.

 

So basically the shadow cast on the cardboard was used to figure out how soft the shadow needed to be. That is amazing. You are equal parts scientist and artist.

 

In any case, I didn't know that changing the diameter of a klieg affected its shadow. That is good to know.

 

Regarding the rays cast, what does increasing that do? Make it smoother? Softer?

 

Thanks for the notes.

[R Reynolds]

Regarding the rays cast, what does increasing that do? Make it smoother? Softer?

The softness of a shadow is only dependent on the light source size, the distance from the source to the shadow casting object (shorter distance = softer transition) and the distance from the object to the surface on which it shadow forms (longer distance = softer transition). More rays just reduces the shadows' granularity, as you say making it smoother, but increases render times. So if you wanted to show a character walking through the shadow of the peak of the central spire of Stian's Nidaros Cathedral and you wanted convincing ray traced shadows, prepare for longer waits.

[animas3D]

I see, thanks. That's interesting. There is an option under the shadow options for a klieg that says distribute in passes. Do you know what that means?

 

Thanks!

[jakerupert]

For further testing I exactly copied Rodger Reynolds sun setup into my scene and that`s what I get now.

 

A little too bright in the Santas face and the locomotive strangely enough doesn`t seem to cast a

shadow on the track.

 

Also Rodger in your setup it seems to be quite difficult to adjust the sunlights direction, right?

[robcat2075]

and the locomotive strangely enough doesn`t seem to cast a

shadow on the track.

 

The sun seems to be aimed directly along the length of the train so the shadow is covered by the train. Try aiming the sun from the side of the scene rather than the front.

[NancyGormezano]

I see, thanks. That's interesting. There is an option under the shadow options for a klieg that says distribute in passes. Do you know what that means?

 

It means the shadow (ray tracing) computation will be spread out among the passes, taking less time to compute, but shadows will look less smooth (more grainy)

[R Reynolds]

the locomotive strangely enough doesn`t seem to cast a shadow on the track

I see all kinds of strangeness in that image. There's something odd about the ties and ballast (stones) underneath the rails. I can see the shadow of the locomotive falling on the rails directly in front of it but nothing below that. The sides of the tunnel are in deep shadow but the ties and ballast inside are not. The chassis of the truck doesn't seem to be shadowed by the flatbed trailer and the cargo of pipes don't seem to cast shadows on the flatbed. The interior of the loco should be totally shaded and yet it's glowing red.

 

My guess is there's some material effects going on. Are the ambient intensities of all your materials set to 0? I'd suggest deleting all materials and use the same shade of grey on everything just to give you a neutral starting point. I've attached a render of what a 2 ft. diameter cue ball looks like in my lighting setup. Its white RGB values of 212, 212, 212 took some experimentation to find the right balance with respect to it's specular highlight. I suspect your going to have to adjust all your materials to make them work in this lighting setup.

 

it seems to be quite difficult to adjust the sunlights direction, right

My solution was to put a Null at the centre of the scene and constrain both suns to aim at it. Then I move both suns by changing their X,Y and Z numerical values. I suppose there's some way to lock the negative blue sun to the white sun so you only have to change one set of values but I've never looked into it.

[itsjustme]

I suppose there's some way to lock the negative blue sun to the white sun so you only have to change one set of values but I've never looked into it.

 

It should only take two constraints...a "translate to" and "orient like" constraint.

 

Hope that helps, Rodger.

[jakerupert]

Hi Rodger,

 

Thank you for looking into it.

 

Yes the rubble on the track are normalmapstamp that somehow messed up I guess.

I will have to check.

The mats I will check also.

The matcapshader on the tunnelentrance doesn`t show up like I would expect.

So I guess I would have to set an extra light for that?

Also is a skydome ?

I have none so far.

 

The steering rig for the sun I got established with both of you constraints.

[R Reynolds]

I guess I would have to set an extra light for that?

What I was going for with this lighting set-up was an all purpose, convincing sunny day outside environment. With that in mind, any object (that isn't itself a light source) that gets put in this environment and looks wrong needs to have it's materials adjusted not a special light.

 

Also is a skydome (needed)? I have none so far.

The way I use a skydome, it's only there to support the decal of the sky. Its ambient intensity is at 100, casts no shadows, receives no rays and as such has no effect on the lighting setup.