This explanation is for those who already know how to use both programs, and can already adjust the ground plane and lighting so that the figures look like they belong there, but want to know the trick for making the shadows.
It's simple.
Make your picture as usual, and save the render. Then, in Poser, set the background color to white, make the ground plane visible, and set that to white too, with no texture or bump.
Don't change anything else.
Make a second render, rendering over the background color.
Open both in Photoshop, get the move tool, hold down the shift key, and drag the shadow image onto the normal rendering. That will line up the two pictures perfectly.
Choose Multiply mode, and your shadows will be all there and perfect, but the figure will be too dark.
Load selection, and choose the Alpha 1 channel that Poser automatically makes.
Hit the mask button, and hey presto! Perfect shadows for your rendering!
Use the smudge tool to blend them with the texture of the photo.
For beds and tubs and cars and things make white props or use cubes and cylinders if you can get away with 'em. Anything to cast the shadows on.
To put things from the photo in front of your figures, make a copy of the background layer in the render, delete the original, and drag a copy of the photo you used onto your picture. (Make sure they are the same size.) Put that under the Background Copy layer, add a mask to that layer, and reveal whatever parts of the photo strike your fancy.
I'm sure you can take it from here.
If you don't understand any part of that, or if you want to see the steps illustrated, check out the longer version.
If you have a question, write to me and ask it!
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