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Soft and Hard Shadows


barkest

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My default position has always been that soft shadows take longer to render than hard shadows. In Cinema 4D its the opposite way around. Have I been getting it wrong in VW?

 

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Rendering hard or area shadows is much more computationally intensive

 

thanks

Edited by barkest
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  • Vectorworks, Inc Employee

I'd question this, would hard shadows make my interior renderings more accurate? In many of my scenes I have a combination of both. If there is sun light present hard shadows it is, if it comes from a distance light bulb then vanishing shadows help.  Does this take longer? I think I'll run a test on this one.

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On 28.4.2017 at 2:41 PM, grant_PD said:

3 types of shadowing:

Hard=Raytraced, which takes a long time

Shadow mapping=depending on the sample size, can be very fast

Area shadows=takes a long time

 

Hard to know what VW means by "soft shadows." Are they shadow mapped or area shadows?

 

 

You mentioned the shadow types :

 

Mapping = fast + inaccurate

Raytraced = not slow + very accurate, but unrealistic in a way that we do not have real light sources with zero size

Area = slowest + accurate

 

Shadow Mapping is soft to very soft, depending on Map Resolution. The problem is

that softness is independent from distance. A pole's shadow will be a soft at its base as for its top.

It is a bit like the 2017 drop shadow effect.

 

Area Shadows softness is dependent on distance from the object casting to the surface, to the surface

receiving the shadow. As larger the distance, the larger the softness area > accurate.

It works a bit like Ray Traced Shadows, just that you need to trace more than 1 Ray (Samples),

from different directions and finally interpolate in some way.

That is why that shadow type ist harder to compute and so slower.

 

So if you watch those soft shadows from VW,

if short shadows are sharper and longer shadows more blurry, those will be true and slow area shadows.

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41 minutes ago, zoomer said:

As larger the distance, the larger the softness area > accurate.

 

My understanding is that the further away the harder the shadow (the sun), the closer the softer the shadow. In addition its not just down to distance it is also affected by the size of the area light. Larger area lights will give softer shadows.

 

 

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Yes,

 

As larger the Light - the softer the Shadow

As farer the distance of the Light to the shadow casting Object - the sharper the Shadow

And,

As farer the distance the Shadow Rays have to travel from the shadow casting Object to the

Object receiving that Shadow - the softer the Shadow.

 

You can take your desktop lamp at an 45° angle and shine on a pencil that you put vertically

on your desk. Where the pen meets the table (=short distance) the shadow will be quite sharp,

while the shadow of the pen top, that has a larger distance to travel is much softer. 

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  • Vectorworks, Inc Employee

Sorry for the delay, I was away at AIA Orlando booth running 3d and rendering demos, now, we are back and I have something to share. By using Pat's time script I was able to compare the time it takes to render four viewports with the same properties but different lights configurations and two rendering styles. To my surprise, sharp shadows with no ambience lights take very little time compared to a light source with soft shadows. Now, when we get close to produce a better quality rendering we add some environment light and a number of light bounces, here is where the time to my taste is irrelevant, the waiting period was minor.  Here are my notes:

 

 

Test shadows plain.jpg

Test shadows w light bounces.jpg

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