#7682 closed defect (fixed)
WMS-cache does not "tile" requests one same boundaries between session resulting in re-requests of already cached areas
Reported by: | jjaf.de | Owned by: | team |
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Priority: | normal | Milestone: | 15.08 |
Component: | Core imagery | Version: | tested |
Keywords: | WMS cache hasExactMatch tiling | Cc: | jttt |
Description
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".
Attachments (0)
Change History (10)
comment:1 Changed 11 years ago by
Cc: | jttt added |
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Type: | enhancement → defect |
comment:2 Changed 11 years ago by
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.
comment:3 Changed 11 years ago by
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).
comment:4 Changed 11 years ago by
Native request levels may decrease the image quality in some cases, but I guess for the average user, it would be an improvement.
comment:5 Changed 10 years ago by
Component: | Core → Core imagery |
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comment:6 Changed 9 years ago by
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.
comment:7 Changed 8 years ago by
Milestone: | → 15.06 |
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When scale matches exactly, the cache should be used.