Video HDRi

Support Lighting and Rendering
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Hey folks! I’m hoping someone might have an answer for this, as I haven’t been able to find much on the topic.

I recently got an Insta 360 X4 camera. In theory, that camera can record 360 HDR video (And export it either as ProRes 422 MOV or H.265 MP4 (with MacOS devices even having the option for Dolby Vision encoding).

With that in mind, I assumed that you can use that footage as an animated HDRi for lighting environments.

Picture this: Attach this baby to the roof of a car, film the car from a drone and BAM perfect lighting for exact position of the car at all times. Tunnel? no problem. Clouds come in? No problem! As long as the 360 footage and the a-cam footage is synched up, you’ll always have perfect light reference! Should make compositing for movement-heavy scenes massively easier!

But… it doesn’t quite seem to work. Or at least from my tests, the lighting never seems to be quite as strong as necessary. For example, I’ll be filming on a bright, sunny day, but the HDRI never seems to replicate that bright, intense light. The entire scene feels very ambiently lit, as if on a cloudy day. The direction of the light is vaguely accurate, but that’s about it.

I’ve tried every different combination of video encoding and color space available on the input node, but none quite seem to do the trick. The closest I’ve gotten is the “Khronos PBR Neutral sRGB” color space + H.265 MP4. However, while that color space better replicates the intensity of the light (bright, directional sunlight casting very harsh shadows, etc.) the actual colors seem to be very far off – like I’ll randomly get bright orange instead of blue skies. Clearly that color space isn’t intended for any of the export options available for that footage.

I’ve also tried to convert the footage to an HDR image sequence. Same result.

If anyone has any clever tricks for this (maybe some different encoding, or some genius node combination), I’ll be grateful for the help!

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HDRI image have multiple stops, you’re creating a spherical video. Jorgen HDRi has a very detailed post about it, and Weta Digital a tutorial on how to create it.

The lighting setup that you’re thinking about was used in a few Black Widow shots:

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The problem is your camera is recording high dynamic range, then tonemapping it into a low dynamic range format. You don’t have true HDR files coming out of it.

Here is an HDRI from polyhaven on top, and a tonemapped version on bottom:

image
image746×748 129 KB

and here is the same thing, but with an exposure adjustment:

image
image747×739 11.8 KB

The sun almost disappears in the tonemapped version.

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Oh wow, so even H.265 DolbyVision isn’t good enough? I always assumed that was true HDR. Unfortunate.

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Thanks for the resources. I’ll check em out!

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Dolbyvision provides 12bits of color depth per channel, up to 4096 levels of brightness. This is plenty for displaying, but to capture the full depth of illumination, you simply need more data.

.exr hdri files are 32bit, allowing over 4 billion levels of brightness.

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