Time-Lapse Renders

[pironic]

Originally opened on the Overviewer Main Repo overviewer/Minecraft-Overviewer#799

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Original Comment By @pkovac:

It should be possible to efficiently present a timeline slider to enable users to scroll through and view changes to the map over time.

Throughout this explanation I will use 'world' to refer to the Minecraft region files, and 'map' to refer to the completed rendering output of Minecraft-Overviewer.

Procedure

1. User backup scripts fetch a fresh snapshot of world t, assuming a world t-1 exists already. Utilities such as dirvish simplify and optimize this usecase.
2. User scripts do a recursive copy of t-1 map using the -l option to use hardlinks.
3. Render t map on top of the hardlinked copy of t-1 map. Current semantics in Minecraft Overviewer's file saving should ensure that t-1 map tiles that need updating are replaced only in the t map copy, since save /rename or delete/save are used instead of truncation.
4. User script generates a list of links or a modified web asset file allowing users to navigate between maps at different times.

This procedure has a distinct drawback in that clients' browser caches will not properly reuse tiles that do not change between each timestamp. Tiles that do not change would still be represented as distinct URLs. Not only would this drastically increase bandwidth consumption to the host, it would impact the fluidity with which users could navigate the timeline.

I'm unsure of how the Google Maps API works internally, so it may not be possible to do what I'm suggesting elegantly. There would need to be some way to maintain a reference table of the "last change" of a given tile coordinate so that the appropriate URL could be used.

Additionally, it would be ideal if a timeline slider could be presented in the stock web assets.

I'm not sure how feasible any of this is, as I'm not a webdev. It seems to me however that the potential costs would be fairly modest.