[josm-dev] Microsoft gains access to aerial imagery

[Alan Mintz]

At 2010-12-01 00:20, =?ISO-8859-15?Q?Dirk_St=F6cker?= wrote:
>On Wed, 1 Dec 2010, andrzej zaborowski wrote:
>
>>Dirk, I now modified the html file to query the Bing REST api as
>>described by RichardF and display the logo and the imagery providers
>>on every fourth tile (about every 1024 px down and across).  The only
>>thing is that the logo is not clickable, obviously.
>>
>>You might wanna update just in case someone uses this (I know it's
>>suboptimal compared to direct tile access).
>
>Copied to http://josm.openstreetmap.de/wmsplugin/VirtualEarthSat.html

So, I added "html:http://josm.openstreetmap.de/wmsplugin/YahooDirect.html?" 
to my list of WMS servers. A couple of issues/observations:

1. Performance is similarly slow to Yahoo via webkit

I open the "jump to position" dialog (^G by default), paste the URL 
"http://www.openstreetmap.org/?lat=34.086307&lon=-117.477256&zoom=18" and 
then set the zoom to 31. Now, I add a layer for Bing imagery from the WMS 
menu. It takes about 30 seconds for the first tile (NW corner) to appear, 
and the two below it appear within a second or two afterwards. Another 20 
seconds or so to start and quickly finish the second column, and another 45 
seconds to start and quickly finish the third column - a total of 90-120 
seconds for a 1100x1000 pel view area that is offset half a tile from the 
boundaries in each direction, needing 3x3 tiles to cover the whole thing.

This is similar in timing to Yahoo using 
"html:http://josm.openstreetmap.de/wmsplugin/YahooDirect.html?", and in 
contrast with about 20 seconds total for USGS HRO using 
"http://imsortho.cr.usgs.gov:80/wmsconnector/com.esri.wms.Esrimap/USGS_EDC_Ortho_California?service=WMS&version=1.1.1&request=getmap&width=500&height=500&format=image/png&SRS=EPSG:4326&layers=Riverside-SanBernardinoCA_0.3m_Color_Mar_2008&".


2. I'm getting images of vertical and/or horizontal scrollbars at some of 
the tile borders at random, as seen here: 
https://sites.google.com/site/am909geo/osm-1/20101201174201.jpg?attredirects=0


3. At random, I'm getting a red tile with black writing that says:
ReferenceError: Can't find
variable: OpenLayers

Other tiles around it are ok. Reload Erroneous Tiles does not fix it.


4. In this area, it accepts requests down to JOSM zoom levels of 7m, which 
is 0.07 m/pel, and the imagery returned appears to have a native resolution 
of at least 0.10 m/pel. It's far better than the somewhat hazy USGS 0.3 
m/pel imagery, which is now the second-best available. You can even make 
out things like individual tree branches, the shadow of some sort of 
flotation device in the swimming pool, etc. Very cool!


5. Looking at this area: 
http://www.openstreetmap.org/?lat=34.102171&lon=-117.568182&zoom=18 , 
comparison against the USGS Urban HRO April 2007 0.3m imagery is similar 
for construction in the area places the Bing imagery somewhat (maybe 1-3 
months) later - not bad, not great.


6. There is a road centerline benchmark that appears at 34.101866, 
-117.569148 +/- 0.6m in the USGS 0.3m imagery, and at 34.101874, 
-117.569162 +/- 0.14m in the Bing imagery - ~1.6m at 305 degrees away. This 
seems pretty well-aligned for our purposes. I've got some high-precision 
benchmarking I did in the area, which I'll look at later to see what the 
complete story is.


--
Alan Mintz <Alan_Mintz+OSM at Earthlink.net>