Semi-transparent objects when rendering on a background image with GI enabled

[enrique.monzo]

I am trying to render a simple object on a background image. I set up the background image in the World node-tree:


Those are the VRay settings I am using:


If I render the image with GI disabled, the object is fully opaque (as expected):


But if I enable GI, the object looks semi-transparent:


Why the object does not appear opaque? What I am doing wrong?


[Using the latest builds of Vray for Blender and VRay Standalone]

[enrique.monzo]

I found a solution, switching the mapping settings of the background image in the World tab from Environment/Screen to Projection/Perspective:


Now it is possible to use properly the Wrapper material to cast shadows using Sun/Sky illumination with GI enabled:


Just one question: Is this configuration (World-->Mapping Settings-->Projection/Perspective) the correct one to use images in the background of the render (for camera matching)?

(Note: Please, move this thread to another section of the forum if required)

[Stugys]

nice one, i did not know that feature, i thought i should make that in image editor PS or Gimp or Krita

[enrique.monzo]

Hi Stugys,

I think that postproduction in an image editor (Affinity Photo in my case) is always the correct way to create the final production image.
But I consider this method a fast way to have an overview of the matching of the CGI objects (location, perspective, lighting, shadows, etc.) with the real background, before exporting the render elements for final postproduction.