If I position a light behind the head, I will often get it to shine through their eye sockets/mouth/nose, is there anyway to stop this?  Thanks

Do's this happen also when you render?

I know that V4 shows the background through her eye's in preview, but when rendered all is ok.

If it happens in rendering, try to turn on/off "remove backfacing polys" in render settings.

Poser doesn't work correct if a light has less than 100% shadow (value 1).

Here is a scene with a light behind the wall with 100% shadow, directed to the ball:

Same scene with shadow set to a lower value:

The light shines through the wall and illuminates the ball from the backside.
Just an unbelievable error.

Quote - If I position a light behind the head, I will often get it to shine through their eye sockets/mouth/nose, is there anyway to stop this?  Thanks

You never said so - do you have shadows enabled? If not, then the answer to how light does not reach everywhere in Poser - use shadows. Are you using depth-mapped shadows? Then you probably need to increase shadow map size, or better yet try ray-traced shadows.

ADP- If you make shadows anything less than 100%, you have already violated realism. The feature only exists because there have been cases where you could avoid adding extra "ambient" lights by decreasing the shadow intensity, making a single light serve double duty. With IBL today, this is a less-than-useful feature.

I don't have time to try it at the moment - what value were you using for shadow intensity? I really don't know what you expected. Was it at 98%? Then that is a bug. But was it at 50% or less? Not a bug - you told it to let 50% light leak through then. That's what shadow intensity means - let some light leak through.

I don't have time to try it at the moment - what value were you using for shadow intensity? I really don't know what you expected. Was it at 98%?

Amything greater 0.0 and less than 1.0 leaks through.

That's what shadow intensity means - let some light leak through.*

If this is true, more professional 3D-applications (my Cinema 4D) than Poser are doing wrong :)

Go out and watch the nature. You will find a lot of soft (not 100%) shadows (means:light, not dark).

Sorry, I do have 100%, 1.0 intensity on the shadow.  But it's often like the back of the skull is missing

@Whatte: Yes, this is a well known error based on how Poser handles light. Especially with DAZ figures (don't know for other figure-geometries). There are some tricks to get a resonable result. Ambient occlusion, for example, may help. Or not to use infinite light and setting the light to raytrace mode. May help. Not in any cases. If you have P7, try Pointlight for lights behind the figure. One or the other works for me, most often. But actually I try to avoid using Posers render-engine (not allways possible, because other apps do not have support for Posers shader system).

I'm not following any of this, adp. Help me understand.

You said "this is a well known error" - but what is a well known error? We haven't even seen the render. It would be better to analyze the render, and then ask questions.

Whatthe: Could you post a render,  please? I have various suspicions, but I need to see the issue before I make too many wild guesses. For example, if you can see through the iris, it may be because you mistakenly made the iris transparent - thus we see into the back of the head. Or perhaps you are using refraction, and the ray bias is too low. There are many possible issues.

adp:

Whatthe has said that the shadow intensity is 1.0 (100%) so that is not the issue, but I still don't understand what you say about it being buggy.

Shadow "softness" (shadow blur radius) has nothing to do with intensity. The shadow intensity is specifically to allow some light to leak through. The amount that leaks through exactly follows the shadow intensity value. If you set it to .8 (80%) then 20% leaks through. I'm not suggesting that shadow intensity is something you want to use. It is an old leftover technique from before the availability of IBL. Nevertheless, it does work correctly, if not realistically. (Trying to use it to create some "ambient" light will still allow specular reflections, which is not realistic.) It is much better to use IBL for ambience, to decrease the intensity of shadows.

I will now demonstrate. I have 5 renders to show you. Please bear with me.

I am using depth-mapped shadows, but ray-traced shadows could be used as well. The results would be better with ray-traced shadows.

I have set the shadow intensity to 1.0 (100%), so in the very middle of a shadow, no light passes through. However, I'm using a shadow blur radius of 20, giving "soft shadows" - meaning the edges are not sharp, they are blurry.

Notice that the middle ball is showing a specular highlight. That is not realistic. However, it is doing what I told it to do.

Here is the same scene, with shadow intensity 1.0 (100%). However, I added an IBL for ambient lighting. This is much more realistic, as the impossible specular highlights are not produced in areas that are in shadow, with respect to the infinite light.

With this type of shadow, the amount of blurring will change depending on how far the shadow is from the shadow casting object.

Depth-mapped soft shadows don't do this - they have the same amount of blur regardless of how far the light has travelled.