Indigo Renderer Forum

I Just noticed that if I render a simple flat white surface illuminated by a sunlight, the image is darker at borders: the wider viewing angle, the bigger is the effect
(The effect is visible in every scene, but a white surface makes it more visible).
This is a real problem for me because i need to join six images with a 90° degree viewing angle (a cube) in a spherical proiection.

Can I avoid this effect without post processing the image and without changing the viewing angle (that for me is mandatory) ?

Thanks

This vignette effect is akin to reality and AFAIK can be naturally removed, otherwise it would appear in all photo. I think it has to do with aperture, can be wrong though

I tried changing aperture: a smaller one isn't useful, a really big one reduces my depth of field and almost everything goes out of focus (i get a uniform blurred white image)
The only way I can imagine is to combine my white vignetted image together with the real one with GIMP, but it's hard to obtain a good result without loosing image quality...

No, from my experience that's correct pixie, or with a wide camera angle. In the following image, camera angle is above 120°:

My answer was incomplete... vignetting in Indigo is not an option, although it's a physical effect it can indeed prevent stitching.

There is a tutorial in these forums (maybe it's a scene in a wip) showing how to create a latlong hdr environement output with a virtual chrome strobe, maybe you could do that and convert later to cubemap with a free app like hdrshop (if it can, I believe so) ?

Now, you can request either making vignetting an option, or adding an environment camera, wich by definition don't use vignetting... I guess the second is more popular

Vignetting is literally caused by less light making it to the "film" at oblique angles.

Render to .exr and open in Photoshop, for example, and it's quite easy to "correct" - and unlike real life, Indigo's vignetting is perfectly aligned.

Ok, Thanks to everybody.
I'll surely solve the problem searching for the virtual strobe or generating a white vignetted image and subtracting it from my real images.
Meanwhile I'll request an environment camera, endeed useful for making env_maps