Closed GoogleCodeExporter closed 9 years ago
Just tried r7f23a683d2b3 and did not notice any more instances of the map layer
disapearing (sessions were shorter than before, though.)
However, WiFi catalog update is becoming an ever greater issue. Often the
catalog layer will stop updating completely. Regions that have been rendered
will usually continue to show on the map but nothing new will be drawn as new
regions scroll into view. Sometimes even parts of already rendered areas will
blank out.
This may have to do with the amount of data in the catalog (I've imported the
WiFis I have logged over the past few weeks, so data in my area is quite dense
as I've been mapping entire neighborhoods over the past weeks), but it will
become an issue as the amount of data in the WiFi catalog increases. Densely
mapped cities (Paris) may already experience issues.
Original comment by mich...@vonglasow.com
on 24 Sep 2013 at 10:16
That's strange: I see the wifi catalog objects even earlier than the session
objects.
I also checked indices twice, but they seem to be good.
You mention you've imported the wifis you have logged over the past few weeks:
did you consider some kind of clustering?
The original wifi catalog uses the server-side clustering, so there's exactly
one point for each wifi. If you're importing raw data, the number of points
might become really huge..
Original comment by wish7code
on 25 Sep 2013 at 9:15
I do use some clustering as well. I average over all lat and lon values for a
given BSSID (so each BSSID shows up only once) and also ignore BSSIDs already
in the catalog. That gives me exactly one point per WiFi, but that is still
quite a lot.
One thing I have noticed today is that often the WiFI overlay will show just in
the southern half of the map, and periodically a stripe on its northern
boundary will be removed. (See screenshot.)
Could serialization be an issue here, similar to the current session?
Another idea I had: round lat and lon to 4 decimals (accuracy of ~10 meters,
which should be sufficient for visualization) and return just one record per
position. For the map view, it doesn't really matter how many WiFis are in a
given location, the important thing is that it's been surveyed and I should
better concentrate my mapping efforts on some other area...
Original comment by mich...@vonglasow.com
on 25 Sep 2013 at 9:53
Attachments:
> Could serialization be an issue here, similar to the current session?
No, wifi catalog objects aren't de-serialized, it's just raw access to the wifi
catalog database.
I've overlooked something so far: some time ago, I implemented a hard-limit of
2500 objects to be displayed.
(Reference:
http://code.google.com/p/openbmap/source/browse/android/src/org/openbmap/utils/W
ifiCatalogMapObjectsLoader.java#138)
Do you have a build environment ready to play around with that limit (removing
it completely, or increasing the limit)? I would be interested, whether the
problem is gone then and how Radiobeacon performs when there's no such limit in
place.
In case you don't have a build environment in place, just drop me a line, so I
would provide binaries..
Original comment by wish7code
on 26 Sep 2013 at 11:52
Or three lines above, as you suggested:
replace sql by
SELECT round(latitude,4) as lat, round(longitude,4) as lon FROM wifi_zone WHERE
(latitude > ? AND latitude < ? AND longitude > ? AND longitude < ?) GROUP BY
lat, lon
Original comment by wish7code
on 26 Sep 2013 at 12:27
Nevermind.. Have a look at r8879fc8c6fe0 which implements both..
Original comment by wish7code
on 26 Sep 2013 at 2:20
Thanks a lot, I'll give it a shot.
Today, when going north, I noticed that the WiFi layer was OK for approximately
the lower half of the screen, whereas the upper half was bare of WiFis. So it's
probably related to some limit on the objects returned, either a bounding box
or the number of objects. I'll try the new build.
Original comment by mich...@vonglasow.com
on 26 Sep 2013 at 3:34
Tested it at the same zoom level shown in the screenshot, and I got a complete
WiFI overlay again. So I can say that at the zoom level/resolution I used
(displaying an area of about 800×800 m), the combination of rounding,
clustering and allowing up to 5000 objects will work for a completely mapped
inner city area.
Original comment by mich...@vonglasow.com
on 26 Sep 2013 at 6:47
Original comment by wish7code
on 28 Sep 2013 at 6:58
Original issue reported on code.google.com by
mich...@vonglasow.com
on 18 Sep 2013 at 10:11