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P Retondo

Shadow mapping "softness"

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Is there a way to vary the softness of a shadow mapped shadow? There's too much of a fuzzy edge for my taste.

VW/RW 10.0.1

WinXP

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......and, is there a way to soften the shadows in Ray Traced shadows??? These are too sharp and hard for my taste.

(some people are never satisfied ;-))

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Hi

I think P Retondo and Propstuff have good points and these features should definately be added to future releases. P Retondo-try putting point or spot lights instead of directional lights, this might help to get more defined shadows.

I would also like the transparency to work if I have mapped (soft) shadows on. I like soft shadows cause they are more realistic but I can't place "people Props" without getting hard raytrace shadows. Someone please tell me that this bug will be fixed in VW10.5...PLEASE!PLEASE!PLEASE!

Thanks.

Shaun

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Hello:

The Detail setting in the Custom RW options dialog affects the mapped shadow resolution.

The mapped shadows for directional lights are also affected by the overall size of the model in relation to your view of the model. That means that if you are looking at a small detail of a large model the shadow for that detail may be too coarse, like 1 or pixels of the shadow map. Sometimes the model can be so large in relation to the shadow map that narrow objects don't cast shadows at all.

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Hi Dave,

I am aware that the detail setting is supposed to affect shadow softness. However, with detail set to the maximum, the softness zone is still way to large and coarse - not realistic at all! Maybe this is a bug in v 10.0.1, but there really should be control over the size of this zone. In real life, when a wall casts a shadow on a wall 10' or so away, the zone of softness is no more than a few inches - the distance it takes to move your view of the shadow-casting corner across the face of the sun.

Since this is a universal geometric formula, it seems that realistic shadow softness could be an easily constructed algorithm, with some edit-able constant placed in the formula to allow users some "artistic license." Shadow softness helps the viewer distinguish between planes of color that define an object, as opposed to planes of shadow.

[ 01-20-2003, 02:07 PM: Message edited by: P Retondo ]

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In photography the softness of a shadow is a result of the size of the light source relative to the subject. That's why you see models lit with "soft-boxes"....a light source almost as big as they are and close to them. Moving a light further away makes it smaller in relation to the subject.

Outdoors in "open shade" (i.e. not in direct sunlight but open to a large area of sky) shadows are so soft as to be almost imperceptible.

The softness is caused by light spilling into what would be a hard shadow if the source was a point like the direct sun.

It sounds like you want a brighter light set further from the subject and a lower ambient. Maybe our lights aren't bright enough, I wouldn't know cause I've never lit an outdoor scene in renderworks.

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ccroft, I tried your suggestion to no effect.

I'm afraid Real light and computer simulation are not the same thing ;-)

anyway, I used a 200mm dia, hi-res sphere to cast a ray-traced shadow on a grey "wall" 2m away, and a spot light to light it.

Then I placed the light 1m away at a 45? elevation, then 2m, then 20m and adjusted the light up as it got further away and the ambient down so that the values of the sphere and background were approx equal.

The value of the shadow and the definition of the shadow around the sphere changed (up) as the brighter, further, light increased, but the "sharpness" of the shadow stayed the same at all times.

Perhaps a hugely distant light might work, but I suspect not.

Hmmmmmm......

N.

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I think that the "sun" light object is a directional point source, and it does not "naturally" create shadow softness, because the light source has no breadth. The softness appears to be created by some kind of mathematical function.

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Hello:

The two methods used to create shadows are mapped and raytraced shadows.

Mapped shadows are generated by rendering a Z (depth) buffer from the point of view of the light source. The resolution of that map is determined by the Detail setting (Fast is Low, Final is High, Custom can be set by the user). For spot lights, the map will fit the cone of the spot light, to determine how big the shadow "pixels" are. Point light shadow maps are rendered as six maps in a cube around the light. Directional lights do not have a "cone", and so the shadow map is generated as if looking in an orthographic view at the model, along the direction vector. Since directional lights affect all objects in the model, the map must incorporate all the objects in the model. It is similar to setting the view to an orthogonal view and choosing "Fit to Objects". The shadow map pixel size is therefore usually larger for directional lights than the other two kinds of lights, and if you are looking at the detail of a large model the map will be very coarse.

P, Can you please send me the file you are using to dave@nemetschek.net ? Thanks!

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c.croft; "set the controls for the heart of the sun"? :-)

p.retondo; I repeated the above test with shadow mapped shadows set to maximum detail.

The near spot light produced a reasonable "soft-edged" shadow, but as before, the shadow on the sphere itself was not well defined.

The distant spotlight had good shading definition on the sphere, but the shadow cast looked like a piece of half finished Op-Art from the 60's. A fuzzy sort of checked pattern. (Imagine being very drunk and looking at a grey Tartan fabric )

It looks like you might be able to adjust the shadow definition by changing the distance of the light source/s

Most of my Drafting work involves designing furniture, so I'm looking to place furniture sized objects inside rooms with lights at appropriate distances away.

Whether this scheme will work with your (Architectural?) scale Drgs: ???

good luck

N.

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Thanks, propstuff - it looks like the distance of the light makes a difference with a spot light, but with my directional light (analogous to the sun), the distance appears to be irrellevant. Since I do building massing studies, the spot lights don't work for me, where with room interiors such as you work with it would be the right choice.

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Hi

I always found that renderworks was limited with shadows amoung other things and I can see I am not on my own.

I was just wondering why not use some of Cinema 4D technology seeing that they are Nemetschek's sister company instead of using LightWork classic rendering engine. [Cool]

Any thoughts or feedback would be interesting.

Thanks.

Shaun

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PRetondo, I changed the lights in my test from spots into directional, and still got "fuzzy" edges (but not as nice)

The problem seemed to be getting them the right distance to blur, but not to disintegrate into mush (the "shadow mapping size" problem)

If I understand Dave's comments, the problem is partly that the light "source" is small in relation to the size of the building (hence the shadow map is too large/ coarse to read close detail on the building)

I haven't tried this, but if you make an array (of multiples of the same directional light) which is large in comparison to your building (the photographic Soft Box thing) it might change the shadow mapping detail (???)

Of course; we could just use ray-tracing and adjust the blurr directly with the "Shadow edge fuzzy" preference control in RW 10.5

;-))

cheers,

N.

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