So what I struggled with previously was flickering inside the camera due to the aperture not opening and closing the same amount every time. I’ve fixed that particular issue, and in this render below, flickering is actually caused by cloud movement blocking the sun every few frames or so:
I’m 99% sure this is caused solely because of the sun passing in and out of cloud constantly. The speed of the cloud movement, plus the interval time between frames and the size of clouds means that we go from full sun to no sun between every frame and every few frames, making for a little bit of an eye sore unfortunately. This weather/cloud situation (constant light changes and fast moving clouds) was probably the worst case scenario for this sort of thing.
*edit – Well, flickering was and is partially caused by the sun moving in and out of cloud cover, however I had also messed something up in PTGUI, which caused it to be worse. Here’s an improved, cleaner looking version:
In case you were wondering, the jumping at the start of the rendering was causing by rain forcing me to cover up the camera, hence lost frames.
Future day-length alterations
To prevent this in the future, time lapses will either have to be shot at 60 instead of 90 second intervals, or even 30-45 secs using another CF card to get double the frames. When shot closer together, there is also more scope for frame blending, which is very difficult with wider spaced intervals like these.
Plugging in some numbers to my Google spreadsheet, it looks like to achieve a 14 hour time-lapse with another 128gig CF card, I can get down to 40 seconds per HDRI frame if I start 30 mins before sunrise and end 30 minutes after. That’s less than half the speed that this sky runs at, which could then maybe get slowed down further with frame blending. Of course the file sizes start getting huge at this point – however during the tests I’ve been running in good old Blender, I’m having zero issues. Its not like your software actually loads every frame into memory or anything, and when 1-3 TB drives are the norm, 50 gigs isn’t that big a deal.
Would love to know what you think if you’re an artist or someone who will potentially be using these:
- Is the flickering as big a problem as I think it is?
- Would twice the frames (50 gigs) be an issue?
- What do you think of the cloud/sky speed in general, are you after fast stuff like this or slower more subtle ones?
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