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by jameshart 1526 days ago
Was new to me, but it seems "slippy map" is open-streetmap's terminology for a generic zoomable-pannable web map view, here used to refer to any such UI - whether backed by OSM or google or bing or whoever's map data.

Feels like a weird word choice to me, when 'map' was right there, but who are we to judge.
2 comments
th0ma5 1526 days ago
This is a very old term used to try to describe the Google Maps interface to people who never used an octree multidirectional scrolling and zooming image collection.
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boomlinde 1526 days ago
I would have guessed that they use quadtrees for this, splitting each non-leaf node into quadrants of more detailed maps as you zoom in.
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incanus77 1526 days ago
It's a quadtree of sorts, but is typically done via map projection (web mercator) math so that each tile is replaced by four tiles at the next highest (more zoomed-in) zoom level.

Number of tiles to cover the world at zoom z = 4^z

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michaelt 1526 days ago
Before Google Maps came out, online maps all looked like this: https://web.archive.org/web/20060428160705/http://www.multim... and this: https://web.archive.org/web/20050528023529/http://maps.yahoo...

View the map a single tile at a time, no dragging the map, no moving by less than a tile, no zooming with the mousewheel, every move and zoom a full pageload.

(You'll also notice the older maps are much higher contrast than Google Maps - the older maps being modelled on printed paper maps)

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tyingq 1526 days ago
>every move and zoom a full pageload

That seems expected, since XMLHttpRequest wasn't really broadly standard until 2003/4 or so. Mapquest and other incumbents didn't move fast enough to use it.

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michaelt 1526 days ago
But you could use Javascript to replace one image with another - or to move elements around the page in response to the mouse.

(Back in those days common usage was limited to trivial things like making buttons change colour on mouseover)

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tyingq 1526 days ago
I don't know that would be enough to deal with panning and zooming a tile based map, at least not without some severe hackery.
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jameshart 1526 days ago
Such maps presumably still had the issue of ocean tiles.
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