Hi Jose, > While dealing with QMAPs and Google Satellite imaginery (through GDAL TMS > support) I've come to a couple of possible feature improvements to QLGT > excelent QMAP feature. This is somewhat related and can depend on > Albrecht's proposal / investigation for GDAL error management. > > First QMAP feature I miss, or don't understand correctly. To prevent wrong > queries to Google servers (for non existant satellite imaginery ar certain > zoom levels and above), I created a QMAP that for QLGT zoom levels 1 to 15 > no map should be shown (empty file list for Detail Layer 1), and them, from > zoom level 16 and above, Google Satelite imaginery (.xml file for GDAL for > zoom levels 16 to 2048). > > What I'd expect is, at zoom levels below 16 (8, 4, 2, 1, as using > "quadratic zoom"), no map, a scaled version of the map in the last zoom > level with a defined map (zoom level 16) or just the inability to zoom in > to zoom levels 15 and below. What I get when trying to go from level 16 to > level 8 is zoom level 2048. I don't know if any of the alternatives I > comment above is reasonable or even easy to implement, but cycling to the > greatest zoom level is confusing. > > Maybe the problem is trying to limit the zoom levels for a map the way I'm > trying to do it, and there is better way to do it. But would be a nice > feature to have.
I have to admit I do not really understand what you are doing. Sorry. But I guess you try to work around those "no map" gaps in the google satellite xml. Today I received a version of that XML, that does not fail to load level 1 and all intermediate levels. It's uploaded to the server. Maybe that solves all your problems. To get maximum fun out of it, I added a checkbox in the status bar, that allows you to switch off quadratic zoom on-the-fly. It's all in svn. > > > Second feature / limitation I've come across while dealing with QMAPs. It > seems there is 2^14 (16384) maximum zoom level in QLGT. For normal usage it > is more than enough, but it can be a bit short for some uses. For example, > with the Google Satellite XML definitin file I'm using , a zoom level > x16384 spans an area the size of USA+Canada (1920x1200 screen resolution), > but there could be use cases where this zoom level is not high enough. > Don't know if this is worth the effort, or affects something else. Maybe is > something that should be dealt from the map definition itself. Don't know. Yes, that is kind of very limited. I changed it to 2^17 = 131072. > > > And third, related to Albrecht proposal for dealing with GDAL errors and > the first feature I've commented on, maybe it's possible to detect typical > 404 errors when downloading remote map tiles (don't know if GDAL reports > error details so to make it possible to identify this kind of errors), and > when some threshold if met, just refuse to further query the server at that > zoom level or lower zoom level. And apply one fallback mechanism to show > something on the screen, either the last correct zoom level, a scaled > version of the previous zoom level, just a blank background with a notice > showing the map server errors, etc. Hm, let's see how this will be solved. Oliver ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 _______________________________________________ Qlandkartegt-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/qlandkartegt-users
