Erik Wilde was pointing out the disparities between Google Maps and Google Ditu, or their Chinese version of maps. However, Google Ditu doesn’t have satellite imagery.

There are several easy ways to fix this. The first was to look at the Ditu tiles, and confirm they are the same as Google’s nominal tiling scheme. Which means you can add the China Street tiles as a simple GTileLayerOverlay with Google Maps standard satellite view underneath. This was incredibly easy with Mapstraction and I put up a demo here.

For bonus points I even added a Mapufacture syndicated feed of Erik’s venues for LocWeb2008 and nearby Wikipedia articles from Geonames.

The other way

The terms of how mixing Google’s various tiles together isn’t clear. So the other way to address his issue is to use the freely available data.

Namely, OpenStreetMap for roads, OpenAerialMap or other remote imagery, and run in OpenLayers. Here is the same map done with open data and open source. The resolution or completeness isn’t there yet, but you can see where it’s going and the ability to be use the information as you want is very appealing.

Mikel was inspired to put free data on his iPhone - so he figured out how to
use OpenStreetMap on his iPhone Maps Application.

We tried a number of methods - it should be as simple as changing the tile url that the Maps application queries. But initial “peeking” under the hood didn’t reveal where GMMServerURL is set. In the meantime - Mikel ended up finding the tile cache sqlite database (you don’t want to continually download tiles) and stuffing it with OSM tiles instead. So as far as the Maps application is concerned, its serving cached tiles. Pretty slick.

As Mikel points out, there are some issues to resolve - tile sizes are different on the iPhone, so the zoom levels are off. That would be easy to verify by loading a KML file with markers.

It’s also a slightly sweet answer to Google’s Cease & Desist to MGMaps for using the tiles. Mikel’s “hack” shouldn’t violate anything, he’s just be very considerate to his data provider by pre-caching tiles that have amenable TOS.