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Old 01-15-2013, 08:04 AM   #1
chaorencu
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Question the unit of radius in raytrace shadow?

I haven't payed attention to this before, but today problems appeared when I was dealing with a real size (dimension) interior model. I had to crank the radius up to 500 to get soft shadow of an object which 3 meters to the spotlight, why?

This also raises another question, how to scale a model to correct real size?

Last edited by chaorencu : 01-15-2013 at 05:14 PM.
 
Old 01-15-2013, 10:02 AM   #2
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Assuming you set your unit to centimeter, simply create a cube with the size of 1 1 1 and there you have it - a cube of 1 cm. Most of the unit settings in Maya should be the same. So your light radius of 500 = 5 meter. How soft the light is will depend on the distance from the object too.
 
Old 01-15-2013, 05:18 PM   #3
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Question

Quote:
Originally Posted by Panupat
Assuming you set your unit to centimeter, simply create a cube with the size of 1 1 1 and there you have it - a cube of 1 cm. Most of the unit settings in Maya should be the same. So your light radius of 500 = 5 meter. How soft the light is will depend on the distance from the object too.


Thanks, as your saying, parameters like it depend on how you set maya's world units? But I tried switching between centimeter and meter, the results were the same.
 
Old 01-15-2013, 05:21 PM   #4
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Shadow softness is about the size of the light source in relative to the object. So if both got scaled equally, it make sense of the shadow stays the same.

Strictly speaking tho Maya can act really weird if you set it to anything but centimeter. I really recommend you keep it cm. if possible.
 
Old 01-15-2013, 09:26 PM   #5
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If you're rendering with mental ray, units are simply units. 1 unit in Maya, from whatever unit-type you have selected, will simply be 1 unit in mental ray, which is a centimeter. Thus, all lighting is designed to follow this centimeter, and quadratic falloff only works properly at this scale.
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Old 01-16-2013, 01:39 AM   #6
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InfernalDarkness is correct. And in fact this applies to most renderers like mental ray and Vray etc.

They simply export a number, like: 1

They don't export or read: 1cm or 1m

It means nothing to a renderer usually.
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Old 01-16-2013, 01:44 AM   #7
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Aye, but it could mean everything to a modeler/lighter. For example, living in this ridiculous country, I have to model in inches/feet, and it wasn't until you brought it all to light Bitter that I realized (and executed properly) that I had to scale all my imported geometry down by .394 to make my lighting work properly. Converting inches down to mental ray units, basically. My renderings are much more predictable and therefore take less time to tune, nowadays.

Here is a thread in which we discussed scale rather extensively, with rendertests and some great input from Bitter and others, who have helped me tremendously. Not just in rendering, but in being a nicer and more objective person, too!
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Old 01-16-2013, 02:12 AM   #8
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Old 01-16-2013, 02:12 AM   #9
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