2011 soft shadows not applicable to infinite lights?

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Ajit Menon

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May 3, 2010, 11:55:46 AM5/3/10
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(Sorry if this shows up as a re-post.... I had to edit my "send from" email...)

Anyone played around with the new soft shadows in Soft 2011?
I was pretty relieved to hear that they've finally ported across something that's been in Maya for the longest time.
However, it seems to work only for spot lights and not for Infinite lights... is that just the way it is or am I missing something? Kinda makes it a little pointless if it does not work for Infinite lights (besides the slightly less rendering overhead that it provides)....


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Ajit Menon | CGI artist
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Luc-Eric Rousseau

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May 3, 2010, 12:06:29 PM5/3/10
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indeed it's not implemented for infinite lights

Ajit Menon

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May 3, 2010, 12:17:25 PM5/3/10
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Aaah ... well a quick call to arms for an update with Soft 2011.02?
:)

Christopher Tedin

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May 3, 2010, 12:31:58 PM5/3/10
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Actually, I don't think it is a bug. Soft lights, by definition, are calculated by the penumbra effect of light beams radiating from a non-infinite source, so the light rays broaden from the source and from the "beginning" of the shadow at the base of the object casting the shadow. Infinite lights (sun, moon, etc.) don't have this effect, so cannot be calculated the same way. Shadows will not effectively "soften" with distance. (except in the case of a lunar eclipse or something at that scale.)

Ajit Menon

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May 3, 2010, 12:41:12 PM5/3/10
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Well this new feature in Softimage is effectively a replica of Maya's light angle option for raytraced shadows.
Effectively what the soft shadows  option does is what Area lights do currently (again only for spot lights). 
So it's virtually impossible to "soften" the shadows over distance with an infinite light unless you use the Physical Sun shader (for which you'd need an FG workflow to use it effectively).

And it's not really practical to use a spotlight as an infinite light, now is it? :)

Harry Bardak

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May 3, 2010, 1:18:28 PM5/3/10
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if you set a very narrow cone angle and put your spot light far way, you may reproduce a sun light with almost parralell rays ;)


Harry Bardak
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Http://www.harrybardak.co.uk/
+44 781 661 4147




Date: Mon, 3 May 2010 12:41:12 -0400
Subject: Re: 2011 soft shadows not applicable to infinite lights?
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Thomas Helzle

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May 3, 2010, 2:26:38 PM5/3/10
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Not entirely true (At least not in 2010).
In other rendering solutions (most of them actually), you often have an angle to define how much the lightsource covers in the visible 360° field. I think the sun is like 0.5 degrees, by atmosphere it gets even broader. 5° often looks very nice :-)
Sometimes it's called a dome light, but the principle is always the same - "infinite" lights with usable shadows ;-)

Mental Ray is the last renderer I use that doesn't have it.

Would be a REALLY nice addition!

Cheers,

Thomas Helzle

Harry Bardak

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May 3, 2010, 2:37:07 PM5/3/10
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Your statement isn't really true either, Physical_sun for instance got this option too ( softness for shadow and haze parameter).
It's not up to mental ray but more to your light shader to behave this way.

What you really want may be is a spot light with parallels ray to simulate your sun.




Harry Bardak
TD / Compositor.

Http://www.harrybardak.co.uk/
+44 781 661 4147




From: thomas...@gmail.com
Date: Mon, 3 May 2010 18:26:38 +0000

Subject: Re: 2011 soft shadows not applicable to infinite lights?

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David Rivera

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May 3, 2010, 2:51:38 PM5/3/10
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Hi, I am using Actions -store - transformations Fcuves for the animation of a camera. So I move my camera, store keyframes here and ther for movement and rotation for the duration of X frames.  I store the animated clip into the mixer. Now when I want to create a new pose or movement for the camera for the remainder of X frames, I can´t key the cam anymore.

This camera´s position it´s a null that´s got some expressions to measure distance to target objective from cam position.

Why can´t  I store more animation clips after the first one?
Bests.
David.

Adam Sale

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May 3, 2010, 3:16:47 PM5/3/10
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the mixer clip takes precedence over keyframes.. so if you want to layer in more clips, just mute the clip that is currently driving the camera animation through the mixer, then you'll be free to key and store more poses.
 
When you've got all your moves, load em in and unmute...
 
If your clip doesn't cover a range of frames later on in your timeline, you shouldn't have problems storing your keys..
So if you had a clip covering the first 50 frames of your animation and you are keying the camera afterwards at 60 - 90, you'll be ok.
 
Adam

Matt Lind

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May 3, 2010, 2:03:40 PM5/3/10
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The solution is to implement a cylindrical spot light.  You can treat the soft shadow as the penumbra of the cylinder and control the depth from the position of the light.
 
Years ago when I wrote my own light shaders, I essentially converted the infinite light into a cylindrical spotlight as mental ray still reads the position of the infinite light.  I just had to expose a radius to the user to fiddle with, and voila.  problem solved.
 
 
Matt
 
 
 


From: softimag...@listproc.autodesk.com [mailto:softimag...@listproc.autodesk.com] On Behalf Of Ajit Menon
Sent: Monday, May 03, 2010 9:41 AM
To: soft...@listproc.autodesk.com

Subject: Re: 2011 soft shadows not applicable to infinite lights?
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