Good way to composite Hdri and plates

Hi everyone,

I’m here with a tiny question.
I would like to know the good way to composite some HDRI with plates using matte-shadows.

Here are two images of the scene by HDRI-locations.com to explain my point of view.

First one is with a camera map of the plate.
Second one is with the plane as matte-shadow.

We can see that the reflection isn’t right.
I could imagine that in the most of the cases, it wouldn’t be a problem, but I would like to know how to do it right.

If I put the ground plane as self-illumination, the reflection in the ball would be color-right, but wouldn’t have any shadows. Like this example :

To be clear, I only have a problem with the shadows in the reflection with the right color plate.

How do I have to setup my ground to have the right color and the right shadows in the reflections?

Can be done with a Light/Shadow falloff map to tone down the plane. where shadow hits (mask with falloff as mask).

You forgot the copyright notice for Thomas’ free HDRI/Plate offer…(in case you didnt buy it that is, so sorry if you did heh)

Regards,
Thorsten

Completely right about the copyright, completely forgotten due to the concentration to explain my thoughts.

Could you do a little example so that I could understand right your way to do ?
thanks a lot.

Stan
3LP Team

the reflection wont be right…you need to make the plane not visible to reflections. Also you need to make your reflection environment (I assume its a dome light - full spherical dome.) This way the only thing visible will be the ground below.

@ instinct :
Thanks for the tip, I will try that out, but is this the good way to do it ?
Is it the way we have to do it in production?

@ : Morbid Angel :
I’m very surprised that you say that there isn’t any possibility to do it right.
Because HDRI is good, but with a floor for example, the HDRI wouldn’t far not be enough to have a accurate reflection in the objects.

Is there any other possibility ?
Isn’t there in Vray a option/may where that could be setup to have thoses things right ?
Does all the peoples that use Vray in production have always there reflection wrong? Or does they find that this mismatch is “acceptable”? :roll:

Thank you for your tips anyway, but I would know if there is a beter way to do it, to be accurate.

Stan
3LP Team

Well a camera mapped HDRI for sure will be worse then the original HDR. So you need to rebuild the environment if the HDRI isnt good enough.

Regards,
Thorsten

do a multi-pass render - one for the reflections, then separate shadow passes and comp them in. Split the shadow into GI shadows and direct shadows also…