Automatic Exposure for timelapse HDRi animation

[MANUEL_MOUSIOL]

I am using Hyperfocaldesigns timelapse hdri to create an animation: http://www.hyperfocaldesign.com/time...-sky-full-day/
Because the clouds are moving, brightness is drastically changing on a frame-by-frame basis.
Is there any way to tell the camera (or any other method) to change exposure according to the HDRi environment?
I really dont want to go in and change the settings frame by frame.
Thank you for any pointers!

[stevesideas]

Could you use autoexposure in aftereffects ?

[MANUEL_MOUSIOL]

Never used it. Thanks. I will try!

[^Lele^]

There used to be a specific filter to apply (I think what is there these days is called Color Stabilizer), I used to use it a lot when working on stop-motion to balance the slight exposure shift between frames.
It can be a pain if the camera is moving a lot, and your reference patch gets out of screen, but nothing would stop you from creating a "colorchecker" pass, stabilise that, and reapply the stabilisation to the actual footage, with maybe a simple global gain up or down to compensate for differences between test and final.
Of course, there are a number of commercial tools which employ better algos to the same effect.

If it isn't something you'd like to fix in post (that can have its own problems by virtue of excessive gain showing too much noise), the next version of V-Ray will be able to help you with that (put the pliers away, i won't say more. XD).
Regardless, the question i'd ask myself would be if i really wanted to expose it as the lighting changed, or if i wanted to simulate a viewer not in the same timelapse, ie. simulate some adaptation in between lighting changes, instead of a perfect exposure each frame.
Currently, you can only do that by hand.

EDIT: in fact no, if you felt adventurous, you could use my super old (over a decade, and counting!) matrix exposimeter script, which must be still sitting somewhere on scriptspot.
That, if it still works, ought to be able to expose your sequence by the frame, if you asked it to.

[kosso_olli]

you could use my super old (over a decade, and counting!) matrix exposimeter script

It haunts you! Who knows, maybe you will even be asked to modify it

[^Lele^]

It haunts you! Who knows, maybe you will even be asked to modify it

Ahahah, it does, doesn't it?
I have decrypted the old sources, and my goodness me, i would really not recommend using it...

But no, despite having all but rewritten it in a few different ways (the most funky one is wholly deterministic, for both WB and AE, but boy is it expensive...), a few times over, i don't think that i'll ever have to publish something like that again.
Or maybe I will, for there will be things that are better left to ancillary tools than to a renderer's core, who knows...
The RnD work done in the past two years on Tonemapping and Exposure will surely stand me in good stead, should i ever have to, though.

[Buck]

In Nuke you could use the Curve Tool, set to average intensities.

Nice thing about this, is you can choose what region of the frame it looks at for analysis, or drag the box to the entire frame.

[MANUEL_MOUSIOL]

Sorry for replying so late to my own thread - I never realised there were answers!

Unfortunately I cannot afford Nuke at this time, so I have to stick with AE. Color Stabilizer doesnt work for 32bit files so it would maybe only help at the end when I tonemapped the whole sequence...
but as you say, Lele, maybe having all the frames have the equal exposure isnt the best/prettiest solution anyway.
I tried Vray Next auto exposure, and I have to say it does a pretty good job of keeping the car equally exposed the whole time! But even then the flashing is bothering.
See the result here:
https://drive.google.com/open?id=1tq...losyb1smtNIzdO
I then tonemapped the sequence with a demo version of ArionFX and I thought it made the problem a little less dominant, but still flashing/flickering is bothering me.
Here is the result with ArionFX:
https://drive.google.com/open?id=1O7...rgoDBGeHdLvdU_

Probably depends on the camera angle and how wide or closeup the shot is too, so I will work around that with different camera angles probably. And then maybe adjust a few flickering frames by hand.

Does anybody know any other good tonemapping plugin for AE before I got out and by ArionFX?

[^Lele^]

Sorry for replying so late to my own thread - I never realised there were answers!

Oh man, do tell. Notifications for this version of vBulletin are shaky at best...

Unfortunately I cannot afford Nuke at this time, so I have to stick with AE. Color Stabilizer doesnt work for 32bit files so it would maybe only help at the end when I tonemapped the whole sequence...
but as you say, Lele, maybe having all the frames have the equal exposure isnt the best/prettiest solution anyway.

Very recently a swathe of new compositing tools, either free, or damn cheap, have come up.
All work with node-based, non-destructive approaches of one sort or the other, and most definitely support a full 32bpc pipeline..

I have personally been playing a little (stress on little.) bit with this:
https://natron.fr/
and i also think one which will grow exceedingly well given some time is this:
http://flowbox.io/
Also Blender now has a compositor (which i have not tried.) which may or may not do what you wish.
Last but not least, Fusion also comes free for limited resolution, and quite cheap for individual use.

Notice these are personal suggestions, from me to you: please do not read any company endorsement in them.

I tried Vray Next auto exposure, and I have to say it does a pretty good job of keeping the car equally exposed the whole time! But even then the flashing is bothering.
See the result here:
https://drive.google.com/open?id=1tq...losyb1smtNIzdO
I then tonemapped the sequence with a demo version of ArionFX and I thought it made the problem a little less dominant, but still flashing/flickering is bothering me.
Here is the result with ArionFX:
https://drive.google.com/open?id=1O7...rgoDBGeHdLvdU_

They all (us included, currently) suffer from "blinding" by strong, visible light fluxes (ie. the light hotspot on a wall, close to the source, or a specular highlight).
A lower intensity spec/light in a renderer would blind the AE less, flickering a bit less as a result.

Probably depends on the camera angle and how wide or closeup the shot is too, so I will work around that with different camera angles probably. And then maybe adjust a few flickering frames by hand.

You are very right in your intuition: it wholly depends on the size of the area the very bright pixels cover in the image.
They throw off the average, in that they will make everything darker than it should be.
My old script allowed for low and high value thresholds (say, consider only the 5-95% brightness range, excluding from calculations the two ends), which worked, if wholly manually (so a fiddling affair. horrible.).
Most of the work i have more recently done was to try and automatically exclude the out-of-range values, but given the potential latitude of our renders, compared to the puny one of a camera CCD, makes that effort not trivial at all.
For example, i could have images with values very close to 0.0, by the side of values in the millions, and trying to figure out from the maths alone what is what becomes nasty.
There would be ways to mitigate this inherently, but then a bit more expenditure of ram and processing power may be required, and in any event extreme cases would still likely catch the method out.

EDIT: in fact, would you mind posting said renders, before exposure was applied, as EXR or equivalent HDR format? I wouldn't mind trying out how my script would work on it (i'd ofc repost the results). ^^
EDIT #2: i know how it'd work: SLOWLY.

[MANUEL_MOUSIOL]

Weird with the notifications. In the past I got emails about replies, now I dont get anything...

Thanks for the info about the compositing tools. I downloaded Natron and will check it out. Question is if they have good 32bit support, especially the tonemapping is of interest to me right now.
Again, besides ArionFX, you wouldnt know a good tool to tonemap my EXR files?

I would guess that having a good automatic exposure tool in vray is pretty hard - I mean even with real-world cameras auto exposure is difficult enough with so many options to get what you want!
Very interested to see if the automatic exposure for vray next is going to develop further. A little more control would be great, especially since we are talking about an intelligent system like 3D, where the "camera" actually know what an object is. So having the option to auto expose for a specific object or material in a specific area would be a great addition

Are you still interested in the EXRs? What do you mean before exposure was applied? The AE ones?

[^Lele^]

Are you still interested in the EXRs? What do you mean before exposure was applied? The AE ones?

by any means!
The raw ones, straight out of the renderer.

[Ivan1982]

I see that thread evolved but here is answer to original question.

There is great plugin for AE it's DEFlicker by RE:Vision.

Expensive but worth every penny, it can fix heavy flickering sequences easily, it is 32bit filter and uses GPU. Works by blending frames and of course it's fully customizable inside AE(you can use with masks, animate, specify frame blending, flicker type, etc.).

You can also specify problematic time frame and do processing only for that, you don't have to do whole video, and it will blend in amazingly well.

This plugin also works great on small flickering objects inside video without affecting whole footage like high speed flicker, neon, displays, etc,

Small heads up. It can create ghosting when you have moving camera or objects when using high speed but that is easy to control and avoid as you can have tracked mask and so on.

This was simply the best flicker on the market. My every recommendation as it can save you from re-rendering sequence or doing another time-lapse.

Take a look this demo

https://www.youtube.com/watch?v=RVTk8kbpHE4

Just small caution: This is not magic plug in that fixes everything by itself, it requires tweaking to get you good results, it helps that you have 32bit EXR but do not expect results like proper exposed calm sunny day without clouds.

[^Lele^]

Yes, it's what i used over a decade ago for Stop Motion.
It works, but as you said, it's a tool, not magic.

[Ivan1982]

Yes it needs lot's of tweaking but it has amazing possibilities, here is small example how we used this on specific scene: https://mega.nz/#!FF8Xyayb!gjLxDOrEF...O5Cp7rwRM-eJlI

Top is original VFB output with undesirable results and bottom is final DEFlicker with tons of tweaking and post processing, altogether produced good results for preview purposes you can send to client.

It is way faster than troubleshooting that scene as it can take hours or days if you need 3rd party support and eventually re-render affected sequences again all can take days.

Of course it is always best to create clean results from the get go for final production, unless you don't have a choice like time or resources, then you really do not have a another option but to minimize or maximize usability of recorded or rendered footage.

In most normal circumstances DEFlicker is used locally on groups of fireflies, harsh transitions of light created by lens effects in post, very difficult GI scenarios like rooms visible trough the windows of buildings in background, all those can produce slight variations either with non-uniform noise levels reached or LC/retrace set lower than it required by such intricate details.

There will always be some specific scenario where footage can't be fixed by DEFlicker like missing textures or flickering based on loss of details(missing assets, proxies) and if you lower that only to those few scenarios you will be in great shape altogether.

Take care,
Ivan

[^Lele^]

In fact, i think (but i am not the coder!) that a region selection to perform AE would be cool, and even more an object(s) mask.