I'm lighting a simple scene -  a dark room with two spots, one on a sci-fi chamber and the other shining through a screened vent into the room.  I preview I get nice pattern on the wall from the light through the screen, but when i render the scene the pattern disappears.  I know I'm missing something here, but I can't figure it out.

PoserPro 2012, i7 PC with 24 gigs of ram.

The preview - which looks the way I want it - glass more transparent and the shadows on the wall and the render with no shadows and less transparent glass.

What are the shadow settings on your lights? Raytraced? How many raytrace bounces do you have on your render settings? What's the material on the glass?

Raytraced lights.  Shadows on.  6 raytrace bounces.  Casts shadows in render settings.

Hrmmmm....Did you check the material settings for the lights? Make sure the diffuse color isn't set to black, or something like that? I usually make a black diffuse, black specular light for preview lighting when doing a totally IDL scene...

Diffuse is white as is specular.  If I drop Firefly down to draft the light shows up on the wall, but with no pattern.  The higher the settings the less light on the walls.

Check the falloff of the spotlight coming through the screen. Maybe it's dropping a little faster than preview would suggest. I would also maybe switch that light from a spotlight to a point or infinite light.

The point made no difference.  The infinite lit up the floor.  Neither gave me the pattern on the wall in preview.  No matter what I try, I can't get the look I get in the preview when I do the render.

Apply a mask to the light?

You didn't say anything about falloff. Preview does not implement falloff, so it will be different in render.

You didn't say anything about shadow blur.

You didn't say anything about ...

Why not just post your settings?

I agree with the others.  it appears the vent light is a preview-only light (black specular and diffuse).  there's no trace of it in an overexposed version, unless it's that little corner detail to the left.  the problem of the thin glass transparency is not too challenging IMVHO.

This is obviously due to my complete misunderstanding of the way the preview lights work as opposed to the rendered final.  I'm a filmmaker that uses Poser to make set extensions (matte shots) and CG sets for some of the sci-fi shorts I make.  I obviously want the final result to look as realistic as possible within the limits of Poser.

My confusion comes from the fact that the preview light (a simple spotlight I shined through the screen to get the pattern on the wall) can see through the screen and pick up the pattern.  This same light can shine through the wall or ceiling in preview but doesn't show up in the render - as a found after rendering about twenty times with no light showing up on the wall as it did in preview and then discovering that said light was above the ceiling of the room.

I'm obviously going to have to sit down and do a lot more experimentation to get the near realism I'm looking for.  Using BB Glossy really helped with adding a great look to a Dreamland sci-fi set I'm woking on.

The problem of the glass transparency is very challenging to me, Miss Nancy.  I'm looking for transparency and reflections off the surface of the glass and haven't had much luck so far.  Of course it would help if I knew what i was doing.

Deviations from my setup will be punished with a decrease in accuracy. I don't have time to explain the physics or the implementation problems presented by Poser's quirky internals.

Hope this helps, as they say.

Attached Link: http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2852694&page=5#message_3956259

Just a thought... can ya scrap the vent & put a gel (texture) on yer spotlight?

just wanted to add that:

• bill's shader incorporates the reflect/blinn module which allows specular surface fx with either diffuse sources or directional sources
• preview spots can have deceptive behaviour in some versions, e.g. seeming to go thru solid walls

the problem with gels is another issue, meaning the vent spot would still need to have whatever is blocking it removed. if one can download this scene file somewhere, the experts may be able to help set up the lighting.

below is an example, using kaposer's "pipes room" freebie, showing how one-sided surfaces allow the preview light to illuminate the scene, but block the light on render.

in addition, transparency is previewed in such a manner that can make it look much better than an incorrect poser glass shader.