Whats best way to make shadows plans?

[sky]

does anyone have any suggestions on programs or techniques to shadow existing 3d models on site plans. I usually make models in Autocad but have to draw in shadows manually. What I need is a monochrome site plan with hard edged shadows. any good techniques to make good looking plans?

[STRAT]

in 3d max or any other 3d program, put the site plan picture as a texture map onto a large plain, then put in the 3d models, and use a raytraced shadow light to cast the shadows.

 

or render pass the models onto a separate photoshop layer and use the layer properties to cast automatic shads in photoshop.

[Iain Denby]

 

or render pass the models onto a separate photoshop layer and use the layer properties to cast automatic shads in photoshop.

 

 

Good idea except of course the shadows would suggest everything is the same height.

[STRAT]

true. nothing a few separate layers wouldn't solve

[Iain Denby]

true. nothing a few separate layers wouldn't solve

 

True, but...well...erm...True! :-)

[pmanahan]

I've done this in 2D before using Adobe Illustrator and Photoshop layers by applying a cast shadow effect to the 2d object such as table and chairs. They cast shadows onto a floor but not onto themselves so i had to apply arm shadows to the chairs and all the shadows are the same height so it is good for an effect but not for accuracy.

 

pmanahan

[sky]

Having the elevations reflected acurately in the shadows is really what I need. Something like this picture by Meier. What I've done so far is render in formZ by making all materials white, pump up the light intensity and raytrace. What I get are pure black shadows but no object. Then I composite that image with the the autocad line drawing. Only problem is the image is raster and big. I'd prefer to have it in autocad.

 

*Note the use of line weight on elevation image. Any software that does this automatically??