Photomatch procedure

[visualtracing__]

Hi everyone,

is it possible to know what is the correct procedure to do a photomatch? I have a problem with casting shadows. In all the tutorials it is done with Dome and hdri and it works well. But if we had a background mapped on to a plane, how can I have the shadows projected without altering the light of the image?
in corona I always used the "Tone mapping control" function, very useful because it kept the same light as the image and also applied the shadow cather to apply the shadows above.
In vray however I am not succeeding

thanks

[visualtracing__]

this is a test, I inserted the background into the vfb which you can see at the top of the image and as you can see there is a color difference in the lower part.
I mapped the surveyor in frontal projection so it corresponds to the background. I tried with various render elements but I don't get a valid shadow pass

[zhanet.georgieva]

Hi visualtracing__,

Let's address each of your points to ensure we can assist you effectively.

1. Photomatching: You have to ensure that the lighting in your scene matches the lighting in the reference photo precisely. Any discrepancies can result in mismatches between the rendered elements and the background image. As for the right setup, I recommend following the workflow outlined in this forum post for achieving accurate photomatching results.
2. Tone Mapping Control Function: I'll discuss this with our Development Team for potential implementation or further development in V-Ray.
3. Shadow Pass: It appears there might be some confusion regarding the shadow pass you're trying to generate. In the screenshot provided, you seem to be using the Light Select Render Element instead of the Shadow Render Element. For generating shadow passes, you have to utilize the Shadow Render Element. You can find more information about this in our documentation - Shadow RE.

In order to assist you further and troubleshoot effectively, it would be helpful if you could share your scene setup to examine it closely and offer more targeted assistance. You can either share the scene here or submit a request by following this link: Submit a Request

[visualtracing__]

hi zhanet.georgieva,

thanks for your intervention. I solved it by inserting the background into the background slot present in the vfb. Then I used the "Make Shadow cather" tool and I must say it worked very well.
the only thing I noticed is that it is impossible to save the complete render of the background. I tried tiff, radiance,exr etc. It is always saved without background. However, I solved it in Photoshop even if I noticed a slight difference in the shadow tone present on the background.
thanks

[zhanet.georgieva]

Hi visualtracing__,

There is an option Save in image – When enabled, saves the Background layer to the image.

[visualtracing__]

ohh thanks, I hadn't noticed