Hi all, I've trying to obtain the effect of an extended light source such as a soft box in Poser6. I've tried to use the Shadow Blur Radius setting in the light properties, yet, as I should have expected, only the drop shadows become soft, not the body shadows, i.e., those regions of a model with normals pointing away from the light source. So one needs to emulate a real soft box for that. I know people have done that with an array of spots parented to a box. Not too hard, but somewhat messy and slow, if one goes for accuracy (= many lights). My question: is there any chance one might do this kind of thing with IBL? I don't know much about IBL, but I heard someone mentioning that the position of an IBL light doesn't matter, so one would have to create a light probe that matches the position of the simulated light source. The other thing I heard is that IBL and shadows don't work together, so will this idea be doomed to failure from the start? Or maybe there's some other material room magic that might do the trick? Thanks for any suggestions!

"The other thing I heard is that IBL and shadows don't work together, so will this idea be doomed to failure from the start?" Where did you hear that? Have your tried Ambient Occlusion for soft shadows on your figures/props? Use an IBL Diffuse light source with AO enabled on either the light itself or the materials, but not both. AO gives soft area shadows similar to the effect you see with GI or HDRI.

Thanks maxxxmodelz, but I'm looking for shadows that depend on the position of the light source. Imagine a ball on a plane and a single low light source from the side. The ball should throw a long soft shadow towards the opposite side. AO won't give me that, right? Maybe though I could use an AO light with an appropriate light probe together with a shadows-only spot with the shadow blur radius set to maximum. Another idea that occurred to me is that one could use alternate diffuse to do the job. I've no experience with that, though, so any pointers on how it can be used would be appreciated.

For something like that, I'd try soft raytraced shadows, but I assume you already have? I'd still use AO for the soft ground shadows, but perhaps try and position a negative-intensity spot or point light behind the figure. Negative intensity lights (where intensity value is less than 0 casts "shadow" instead of illumination. If you play with falloff (distance) parameters, it might work for what you want to achieve.

"AO gives soft area shadows similar to the effect you see with GI or HDRI." Oh my god! Why the hell did they take the trouble of making GI and HDRI then, (knowing that even with Brazil / Vray/ Final Render/ Maxwell), it takes hours and hours to get a good GI render? AO lets you simulate GI and HDRI to some extent, Lets just say AO is the Poor Man's GI /HDRI :)

Light in the real world does not emit from a point, but every source has some area, and thus ya get Area shadows?
To get something close to area shadows, put up 6-8 lights where you want your box light. make the ones on the edge raytrace hard shadows with low shadow density and the ones at the centre soft shadows with low shadow density.

object

area Light

Object

Soft Hard Soft

Lights: 1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
1, 4, 16, 13 - Hard Shadows, low shadow density
2,3,8,12,15,14,9,5 - Soft Shadows, Medium Shadow density
6,7,10,11 - soft shadow, low density.

Of course, you don't need so many lights. A spot and 3 directional lights give a good approximation.

Lights: d
s
d d
Spot: soft shadows, medium density,
Directional lights: hard shadows, low density.

:)
Hope this helps.

Message edited on: 06/07/2005 02:59

Thanks, Ashish_s_india! I was hoping there was a way to do it with a single light, but if there isn't, I will be happy with an approximation as you suggested.

Did you try the soft raytraced shadows? This image has just one light - set to raytraced shadows and increase the blur radius. You may also want to lower the shading rate to get higher quality shadows.

"Why the hell did they take the trouble of making GI and HDRI then, (knowing that even with Brazil / Vray/ Final Render/ Maxwell), it takes hours and hours to get a good GI render?" Duh, uhm, hmmm... because real GI and HDRI simulate more physically accurate light bounce and greater tonal/dynamic range, which IBL/AO can not achieve? Do I get a cookie? ;-) "AO lets you simulate GI and HDRI to some extent, Lets just say AO is the Poor Man's GI /HDRI :)" I'd rather say IBL is the Poor Man's HDRI. AO is just a soft "shadow" trick. :-)

'I'm looking for shadows that depend on the position of the light source' odf, I don't want to do a commercial here, so I'll keep the product info to a minimum. You may be interested in a something I'm releasing soon. It's a full photographic studio with highly detailed light-stands and parented spots on the flash-heads. You can IM me for more details if you want. What I will say is that I ended up using spotlights for almost everything. Photographic light is usually very directional, and spots are good for that. The one thing IBL is great for is 'fill' lighting. I made 4 IBL lights for left/right/front fill and one for floor fill (used with a plexiglass platform to light from below). You can vary the intensity according to how much fill you need, and it works really well in conjunction with normal spots. The trick is to get the maps right. I found IBL to be extrememly sensitive and I did literally hundreds of renders with small variations on the maps to get them right. I used Olivier's excellent IBL template (free at RDNA). The flash-heads have a softbox body part, although of course, the actual lighting comes from a spot. I was a bit disappointed with Blur Radius to tell you the truth. Even at the maximum setting of 20, it's not as soft as I'd hoped, and anything between the default 2 and 10 barely makes a difference. mac

maclean, Thanks for the info! That sounds very interesting. Have you tried using an array of spots for the softboxes rather than just one? I think that would be the traditional way of simulating the soft light. I've tried it some time ago with Poser 4 and it kinda worked, but wasn't easy to control.

hi odf, No, I haven't used arrays. I was trying to simulate photgraphic lighting as closely as possible with single lights. I'm not a big fan of 50-light setups. I was a fashion photographer for many years and I know that simple lighting is usually far more effective than complex setups. The other reason is that I don't want to inflict huge numbers of lights on the users. It's already difficult enough on a medium-power machine to render 3 lights with shadows. An IBL fill is much softer than any array will ever be, and very quick to render. mac

Hi mac, You are probably right. That's why I'm looking for some material room trick to get a single light softer. If I find something, I'll post it here. Olaf

Here's an example of what I'm talking about. This first render was done with a single spotlight and soft raytraced shadows. The shadows look alright, but on the sphere itself, the edges of the highlight and of the unlit region are pretty harsh.

Part 2 of the example! Here, I've added four more spotlights, each pointing in the right direction, but forming a cross with 1 foot long diagonals. The light intensity has been evenly distributed between the fice lights. Notice the softer spot and the softer margin of the unlit region. Of course, the effect is very subtle here, but I guess with more lights and a larger array diameter, one could create really smooth lighting here. The problem, as maclean mentioned, is that many lights will need a lot of render time. The setup was actually easier to do than I thought. A square is parented to the central light, and the additional lights are parented to that square.

If you want a still softer highlight on the sphere I suggest you increase the intensity of the middle light and decrease the intensity of the other lights. Also, mking them directional saves some rendertime.