How to add a shadow to a person

I am still in the early stages of getting to grips with Davinici Resolve. 

I record and videos on a full-size green screen that can capture a full shot of a person. I have really enjoyed working with Davinici Resolve and I have managed to get a really decent key and my subjects on to various backgrounds.  The scenes however look very flat and I would like to know how to add shadows that mimic how the sun would cast; i.e. the light source comes from above and casts the performer's shadow on the floor. I have attached an image as a reference to the desired effect that I am trying to achieve.

Can anyone tell me if this is possible? Any help and assistance that you can provide will be most appreciated, thanks guys!

The better and easier way would be to set this up as a 3D comp in Fusion where you build a cyc and use it to catch the shadow cast from the keyed cutout of the person. You could position a 3D light wherever you want it.

Maybe you could do this as a combination of edit page and color page. V1 would contain the Bg. V2 would be a modified copy of the clip on V3. The clip on V3 would be your keyed Fg.

The clip on the V2 is the tricky one. You could crush the video to black for the shadow. Passing the key to the alpha output would work. Softening the shadow may not work though. You could fake the shadow perspective with the edit page inspector settings.

Hi Igor,

I followed your instructions and that has worked perfectly! That has really improved the look of my videos, thank you so much!

Drop shadow + DVE is the first thing that comes to mind, depending on how realistic you want.

Sent from my iPad using Tapatalk

I wonder if the magic mask could be used as well then offset?

I wonder if the magic mask could be used as well then offset?

OP wrote it is shot on greenscreen, so it is way more efficient to key. If it were on random bg, then magic mask could be helpful, but depends highly on the expected quality.