Thanks for using the app! There were only a SMALL number of people using it prior to a few days ago.
We have a crude Dynamic Desktop editor that we use with 24 Hour Wallpaper. I want to release it but it probably won't happen this year. There's a lot of testing needed and UI to be made.
24 Hour Wallpaper uses a format based on periods of the day. We find this superior to Apple's sun angle model.*
*(I appreciate Apple's design and would love to hear the person who wrote it explain the benefits of their format relative to ours.)
Our big realization after writing our engine two times was that what's important is the perception of what time it is in the image, not what time it actually is. The shipping engine is the third one we wrote and it is designed around perception of time rather than scientific time.
In 24 Hour Wallpaper, each wallpaper has an ordered image list for each period of the day (sunrise, day, sunset, night). The engine can take any number of images for each period (1...n). So you can make a DD with our format with just 4 images (sunrise, day, sunset, night).
Apple's format does not specify the direction the camera is pointing. Without that information it's impossible to effectively guess how the shots will appear at a given time. Try looking towards a sunset and then away from it. Totally different. Apple's model doesn't account for this. So in the future they'll probably be stuck normalizing also.
Internally we have a spec for 32-image wallpapers that defines where the light should be in a frame for a given image in the sequence. This is how we continue to keep the wallpapers relatively consistent even though we have 58 highly varied wallpapers. The spec states for each frame where the sun and the moon are on screen and what the angle of light and shadow are.
The latest update to the app contains a converter that translates from the period model to Apple's sun angle model to generate DD format wallpapers. We found it was best to standardize on a single location in Apple's model, and assumed Apple would be testing the location they were using the most.
So I looked at the sun data in the Mojave default wallpaper, then spent a bunch of time with the sun data generator and Google Maps. After a while I found that one day and location that matches Apple's photo data well is September 23/24 at a location in the Mojave Preserve near where theirs would have been filmed. Conspiracy theorists can debate if this is intentional or not given the release date; it's something I've wondered.
Anyway, every DD format wallpaper generated by 24 Hour Wallpaper is coded as being taken at Mojave Preserve on September 23/24. What that means practically is with our model you can create a DD without thinking about sun angle, date, time, etc and output it in DD format with our app doing all the dirty work.
Anyway, thought you might appreciate the details. If the app does well we'll be able to get the editor out more quickly so enjoy
http://24hourwallpaper.com/
-josh