Matrix-weighted Exposimeter

I should thank Vlado (Chaosgroup, VRay programmer) for his contribution of ideas and ways to use the VRay tools, for this one.

It took me (and some of you. Thankyou for bearing with my stuttering brain...) to go through all the pains with the previous versions, but it's finally here.
V 1.0 so to break away from the previous versions, really just an attempt at the concept.

Below is a link to a screenshot of the interface: Distinguishable are the VRay messages window (2.5 seconds to render the small sample image), the exposimeter interface by the side of it, the small sample render (quite clearly overblown) i started from.
Below, the maxscript listener that prints out what happened during exposure, and the rendered image, after exposure.

There's an instructions file that comes in the Zip, but I'll type the most useful infos about it here:
The exposimeter is able to weight out a rendered picture (the sample) dividing it in parts, and assigning to each one a different importance.
It can also be instructed to weight an interval of the pixel values, rather than the whole range, so to avoid blinding/overexposure.
This is in a way very similar in result to what a lens filter does, cutting away unwanted light frequencies. It's fully customisable for areas weights and brightness ranges (check the interface screenshot), so the user can blame me no more for wrong exposures ;)

Further instructions as to the usage are included.
One issue it has (it's a max issue, really), is that after exposure, the environment background map is reapplied through the max presets loading.
If the image was instanced in the material editor, the instanced connection will be broken (and this is the max bug. sorry about it).
Easy enough to copy the envirnment map back in (or clear the mateditor slot, whichever you prefer); in fact no visible change will happen to the renderer, wether the user copies the map back or not.

The exposimeter is contained in the script pack, as it's not  available for standalone download anymore:

A "strange" update which seems to work really nicely, bless VRay.
There's now a checkbox at the bottom of the script window which will attempt to white-balance the physcam automatically.
Notice it will turn itself off after the first time it's run, as running it twice will set the color to a mid-gray, canceling the WB.
Further expositions, in case, if the lights colours haven't changed, can be done without the WB feature turned on.

Follow a few samples:

original image:

white-balanced image:

notice how the white-balance adds subtle timts to the sky...

a more extreme example here (sun with turbidity at 20) which i called from mars to venus...
the normal image:

the white balanced one:

Notice how while it doesn't return pure white colours, the tint is definitely biased out, and simple adjustments would do the trick of white-balancing the render to tastes.

As per usual: "Maxscript->Run Script"; point it to, and go fetch the command into the Lele's VRay Tools category in the "Customize->Customize UI" menu.
DO NOT drag on the max viewport: it will NOT work.

Thanks again for your precious times, folks.



Lele's picture

The exposimeter is now

The exposimeter is now inside the script pack.
Follow instructions for it (it should be easier to install what you want, as well)
Thanks for the pointer :)



tangelder's picture

Hello Lele The link doesnt

Hello Lele

The link doesnt work. Could you relink it?

Best regards,


jacksc02's picture

hey broh! thought I would be

hey broh! thought I would be the first to post a reply!

Lele's picture

Eheh hello there CJ! Glad to

Eheh hello there CJ!
Glad to have you around here! ;)