Transparent Objects for Creating Defused Shadows

I’m trying to create a defused shadow on an object by using a transparent polygon. The reason I’m doing it this way is that I’m rendering a texture in Flamingo and the objects that I need ambient occlusion from are in the rendering so I have tried to make them transparent so they just cast a light shadow but even at 100% transparency they are showing up as dark shadows.

Any ideas?

Would it be possible to post a 3dm file and existing renderings as well as any images explaining the effect you’re after? Please email with the file if it is confidential and please also let me know the version of Rhino and Flamingo you’re using. Apologies on the delay in response here on the forum.