WMS-cache does not "tile" requests one same boundaries between session resulting in re-requests of already cached areas

[jjaf.de]

WMS does pre-load cached areas but since

cache.hasExactMatch()

is false since the viewport is slighty shifted although the complete area can be rendered the whole area is re-requested from WMS-server

Problem

Re-requests are resulting in having a huge cache of [session]-times the size and stress on network and WMS-server.

possible Solution

A solution could be to introduce "tiling" in maybe

downloadAreaToCache()

so that the same bounding-boxes for WMS-requests having shifted viewports are being calculated between sessions or have an algorithm to recognise total coverage from cache instead of

cache.hasExactMatch()

I would suggest the former is easier to implement maybe with help from the tiling-projection.

Workaround

Set viewport to exactly same coordnates and zoom before adding WMS-layer with cache e.g. by using "Jump To Position".

[bastiK]

When scale matches exactly, the cache should be used.

[stoecker]

We have WMS bookmarks, which solve this issue already. THought maybe a tiled approach and some sort of "native" request levels would be a good idea.

[jttt]

WmsLayer already has tiling, method getImageXIndex() convert coordinate to tile index. But scale needs to be exactly the same as before (that's what WMS bookmarks are for).

[bastiK]

Native request levels may decrease the image quality in some cases, but I guess for the average user, it would be an improvement.

[anonymous]

I believe this issue is now fixed, if "automatically change resolution" for WMS layers is checked. This option snaps imagery to specific zoom levels, making manually bookmarking obsolete.

[Don-vip]

skip milestone 15.06

[wiktorn]

In 8526/josm:

Introduce WMS layer based on TMS. (closes: #11255)

HEADS UP: After this patch you need to manually remove JAX-B generated file/class: org/w3/_2001/xmlschema/Adapter1.java to compile the tree again.

• create AbstractTileSourceLayer based on TMSLayer as a base for TMS, WMS and (future) WMTS layers, (addresses #11459)
• WMS layer now uses JCS Caching (closes: #7363)
• introduce new conversion methods in TileSource, that convert both X and Y (lat and lon) in one call. This is necessary for other than PseudoMercator projections
  • introduce TileXY class that represents X and Y indexes of tile in tile matrix/space
  • mark old conversion methods as deprecated
  • refactor JMapViewer and JOSM to new methods
  • change use of Coordinate class to ICoordinate where appropiate
• extract CachedAttributionBingAerialTileSource to separate file
• create TemplatedWMSTileSource that provides the WMS Layer with square (according to current projection) tiles (closes: #11572, closes: #7682, addresses: #5454)
• implemented precaching imagery along GPX track for AbstractTileSourceLayer, so now it work for both - WMS and TMS (closes: #9154)
• implemented common righ-click menu on map view, as well on layer list (closes #3591)
• create separate build commands for JMapViewer classes to easily spot, when josm classes are used within JMapViewer
• remove unnecessary classes of previous WMS implementation - GeorefImage, wms-cache.xsd (and JAXB task from build), WMSCache, WMSRequest, WMSGrabber, HTMLGrabber, WMSException

[Don-vip]

Milestone renamed