OpenSeaMap-dev:Downloadable Raster Charts: Unterschied zwischen den Versionen
Kannix (Diskussion | Beiträge) (→Reason: > Discussion) |
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Lets talk a bit about amounts here and not low stress or high stress. | Lets talk a bit about amounts here and not low stress or high stress. | ||
Version vom 29. Januar 2015, 16:25 Uhr
Inhaltsverzeichnis
Reason for ChartBundler
Lets talk a bit about amounts here and not low stress or high stress.
Using the charts offline on a mobile device. Lets say the display is about 1024x1024 Pixel, then we will need at least 16 tiles per map. If we start on zoom level 8 with the bounding box and continue to zoom level 16 for the harbours, we need around 2 Mio tiles. This 16 tiles on zoom level 8 is about the northern Adria. If we want the Channel just skipping Lands End up to the belgian coast, this would be 6 by 5 on zoom level 8.
- see Discussion
Status Quo
prefabricated charts
- pros:
- low stress on tile servers
- cons:
- set up needed
- needs to be maintained
- not always up to date
- might not fit users needs
Links:
- OpenNauticalCharts (outdated)
- Chart-Bundler (work in progress)
on demand
- pros:
- up to date
- fits individual needs
- cons:
- high stress on tile servers
- users have to do some research, might be a complex task
Links:
- Chart-Designer (work in progress)
- OSM-Wiki
- smrender-online
- MOBAC (banned by most tile-servers due to unreasonable load)
- GMapCatcher
Ideas
cache & proxy tile server
- TileStache provides
- numerous caches (eg. disk, Memcache, Amazon S3, MBTiles)
- TMS and WMS proxy
- fast and faster using nginx
- cache max-age: 30 days?
formats
- served by cache & proxy tile server at minimum cost
- tiles in TMS z/x/y directory structure
- tiles in TMS z/x/y structure encapsulated in sqlite file ( mbtiles )
- tiles in ??? structure encapsulated in sqlite file (OruxMaps)
- tiles in ??? structure encapsulated in sqlite file (Locus)
- single raster file stiched together via script and imagemagic
bounding boxes/ tile sets
- coastal / ocean / open waters
- stick to well known INT-charts
- inland waterways
- generate corridor (x-tiles wide) along centerline of waterway GMapCatcher example
- lakes
- ...
web frontend
- map showing boundingboxes according zoom level transas sample
- sortable table
- search by name/number/area/purpose
- functions:
- search prefabricated files, check age
- trigger generating script in case file does not exist/ is obsolete
