moderately easy way to make ground shadows for worldball / environment spheres / image backdrops

mCasual

place your shadow casting light

place a primitive plane under the subject,

position it so that it will receive the entire shadow

set the render camera to a top view

zoom in until the plane fills the camera's viewport

render this

using a paint program turn this render into a black and white image as shown below, notice i added a blur filter to get soft-looking shadows

apply this image to the Opacity channel of the plane

tweak the Diffuse color, ambient color and the opacity strength until you obtain a shadow that matches the shadows in the backdrop image

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note that there are ways to do this "properly" ... using shadow/catcher which are special shaders
this is probably all explained in the worldball thread of the freepository
http://www.daz3d.com/forums/discussion/23706/P90
and it was explained by Carnite in the Daz Studio 3 days ... search youtube for Carnite shadow catcher
http://www.youtube.com/watch?v=qo2OVy9tf8E

Eva1

Nice quick solution, thanks for sharing it:)

nDelphi

Cool tip!

I have been using primitives to cast shadows on my huge outdoor scenes for when the sky dome I am using has a cloudy sky texture.

For that I just draw an outline of a cloud around an image square I create and then use that for the opacity channel of a square primitive. Then i just position them above the scene and away from the camera and they create cloud shadows.

On the second image is a shadow from a cloud between the flying seagulls and the tower cranes that extends out to the beach. These shadows also look great over buildings.