Auto-exposure oddity

[fixeighted]

I'm not sure I understand this feature or rather 'how' to understand it. Example:

Plane/teapot....one Vray sphere light set to 1.0 and 2cm radius, roughly 5cm from pot.
Camera set to auto-exp, with the light in view seems to be fine. If I move ever so slightly so the light goes out of frame then the intensity shoots up.
No amount of higher intensity alters the brightness and to have it reach anything like the expected result I need to lower it to .00 amounts, until it seems to reach a cutoff
and all is black.
So I'm finding it a bit unintuitive and could use some pointers/explanation please.

I also find it odd when using hdris....trying to logically set values with an hdr and lights also is proving a pain, in exteriors or interiors.

[Vizioen]

I'm not sure I understand this feature or rather 'how' to understand it. Example:

Plane/teapot....one Vray sphere light set to 1.0 and 2cm radius, roughly 5cm from pot.
Camera set to auto-exp, with the light in view seems to be fine. If I move ever so slightly so the light goes out of frame then the intensity shoots up.
No amount of higher intensity alters the brightness and to have it reach anything like the expected result I need to lower it to .00 amounts, until it seems to reach a cutoff
and all is black.
So I'm finding it a bit unintuitive and could use some pointers/explanation please.

I also find it odd when using hdris....trying to logically set values with an hdr and lights also is proving a pain, in exteriors or interiors.

For the autoexposure I have no input, besides that Vray probably looks at brightest parts and tries to expose based on those values besides the other values as well. If the very bright light source is out of focus it will leave room for more exposure of the other parts without completely washing out the very bright spots. But I don't have Vray Next so I can't test.

As for "trying to logically set values with an hdr". Unfortunately there are no rules for making HDRs, and all the different HDRs on the internet have different values and stops etc so there's also no 'one way' to use them or set the multiplier values. Try starting with some real camera values and adjust your HDRs accordingly.

[fixeighted]

Thanks for the reply. It would really need to be tested in Next as it is only, I believe, a feature of that release.
The hdr issue is linked to this. I'm aware of the inconsistencies with their exposure ranges, so that's all good but not linked to this particular weirdness.

As a crude, quick example, an interior (or exterior as that has similar problems) with a domed hdr and also some ceiling spots, with autoexpose on, the hdr that lit the scene and the spots
which lit the interior all have their respective brightness totally screwed with, so effectively what works fine without autoexpose on is then really different, causing me to have to up the multipliers of
the spots to insane values in order to once again see them in the render, although iirc (I'm afk) the autoexposure still does its thing, sort of.

I will post a scene when I get a moment later today or tomorrow, although the simple test I suggested with a plane/teapot/camera/sphere light works to at least quickly see the issue.

I've also sent something else to support about the autoexpose messing with render selcted masks, so there may be some connecting logic to it all. Who knows?!

Chaos knows! Clever dudes...can't expect it ALL to go right the first time

[vlado]

I'm not sure I understand this feature or rather 'how' to understand it. Example:

Plane/teapot....one Vray sphere light set to 1.0 and 2cm radius, roughly 5cm from pot.
Camera set to auto-exp, with the light in view seems to be fine. If I move ever so slightly so the light goes out of frame then the intensity shoots up.
No amount of higher intensity alters the brightness and to have it reach anything like the expected result I need to lower it to .00 amounts, until it seems to reach a cutoff
and all is black.
So I'm finding it a bit unintuitive and could use some pointers/explanation please.

I also find it odd when using hdris....trying to logically set values with an hdr and lights also is proving a pain, in exteriors or interiors.

Can you post some images? Not quite sure what you are describing.

Best regards,
Vlado

[fixeighted]

Apologies - been busy but will do this tomorrow morning, although it is very simple to check. The scene setup, should anyone like to check it is:

A plane with 2 teapots (just for comparison)
A dome light - no texture
Camera (I used a Vray camera)

With autoexposure on, the render is as expected.
With autoexposure on and one of the teapots selected, switch to Render Mask/Selected and the selected pot renders far brighter.

I have tested this many times with different scenes all with different lights/hdrs etc. and the result is always this.
My guess is that for some reason the renderer ignores the lightcache for the scene when masking the element and computes differently, as it appears so much like a gamma shift.

I'm probably wrong though, as although I can definitely spell coding, I don't have the first clue about actually doing it

Here's hoping there is either something I overlooked or a fix somewhere down the line.
It's not a project-breaker, as I can simply not use the feature, however it seems to be useful if WAI

Edit: I just realised I replied to the wrong issue, however this is the one that is causing the most confusion for me at the moment. Please move to the correct section if possible, as it would be good to hear what others find.