Mapping China

while working on a map for the WWW2008 conference in beijing (which is where we will have our LocWeb 2008 workshop), i realized that google maps works for china in a funny way. the main reason for that is probably that the chinese government does not want to see satellite images of china being released in china. so here is what happens:

if you go through maps.google.com, you get satellite imagery (very detailed one), but the maps are pathetic. here is what you get as satellite imagery for beijing. zoom in all the way and you can see the bird's nest (the main stadium of the 2008 olympic games) under construction:

and here is what you get for the same map (still served from maps.google.com) when you switch to the map view — almost nothing, beijing seems only to have five major roads meeting somewhere in the middle of nowhere:

but if you go through ditu.google.com, you get detailed maps of beijing, but there is no option to switch to the satellite imagery, and the interface is in chinese.

this approach makes it probably easier for the chinese government to install filters, so that the chinese people don't get a too detailed idea of what's going on in their country. it was probably part of the deal google had to agree to to get into the chinese market. but it makes it impossible to create a map that provides both good map data and satellite imagery, which is a shame, because google has all that data.

would it be possible to create some google-based map service that combined both data sets, the satellite iimagery and the detailed maps from the chinese site? i am really looking forward to view this blog post from beijing in april and see which of the maps are actually accessible...

Comments

[Andrew Turner]

You bring up an interesting issue with differences in projections. The "offset" is a result of Google's tiling scheme or rendering. Perhaps this is another reason why they don't have Satellite imagery on their Ditu site.

I recently heard a similar issue arose in Google Earth, where recent satellite imagery is offset from previous releases. Therefore anyone that geolocated their models or markers using Google Earth in certain areas will now find them offset.

As 'neogeography', or ubiquitous geographic tools become more popular, and you run into issues like this with non-expert users they'll be confused. Not an easy problem to solve :)

[dret]

thanks andrew! that's really cool! i don't want to criticize your work here, but when i zoom in on http://mapsomething.com/demo/mapstraction/china.html, then the map and the satellite images are a bit off, i would say 100m or so (north/south, it is a bit more in west/east direction). the map-based freeway runs right through the satellite-based conference center ;-)

http://mapsomething.com/demo/mapstraction/china_osm.html looks interesting as well, but the quality of the satellite images and the maps is far inferior to the google dataset. again, that's of course easy to say, and thanks again for pointing to that alternative source of geolocation information!

and as mentioned on http://highearthorbit.com/using-google-ditu-maps-with-satellite-imagery-for-china/, you of course get the full bonus points for adding my information from my locweb2008 map at http://tinyurl.com/2xu9zo!

[Andrew Turner]

Here is a map done with OpenStreetMap, free satellite imagery from OpenAerialMap servers and OpenLayers.

http://mapsomething.com/demo/mapstraction/china_osm.html

[Andrew Turner]

This can be done using Mapstraction or the GTileLayerOverlay function to have a dual overlay very easily.

In fact, here is a demo doing just that:
http://mapsomething.com/demo/mapstraction/china.html

Another option would be to check out OpenStreetMap and perhaps even OpenAerialMap with OpenLayers for some nice OpenData and Open Software options.

You can then bring in a GeoRSS or KML overlay of important markers:
http://mapufacture.com/maps/1426-LocWeb-2-8-Conference-in-Beijing