Tuesday, January 31, 2012 2:35 AM
I found an interesting issue that BingMaps is different from the google maps. For example here I get a 512*512 tile from GoogleMap/BingMaps with the same center point and zoomlevel.
and you can see the differences as following.
I tried to display a vector data (in Spherical Mercator of course) on the map and the GoogleMaps matches better than BingMaps. Does that mean BingMaps has some data issue?
- Moved by Richard_BrundrittMicrosoft Employee, Owner Saturday, March 10, 2012 1:20 PM (From:Bing Maps: Map Control and Web services Development)
Tuesday, January 31, 2012 2:36 AM
Here are the satellite images you can tell the differences.
Tuesday, January 31, 2012 10:19 AMModerator
1.) Firstly, this exact issue has already been discussed in the following post: http://social.msdn.microsoft.com/Forums/en-US/vemapcontroldev/thread/ca104575-f76d-4ab2-be79-550478783348
2.) Google and Bing use different data sources: the aerial imagery is shot at different angles, at different times of year, and the vector data is collected through different sources. Inevitably, therefore, there will be differences between them. Where did your vector data come from? If it came from the same source that Google use then it's not surprising that it lines up with the Google Map better! But that doesn't necessarily mean that it's "right"... Google and Bing both contain errors as well.
3.) The particular difference you've highlighted appears to be the tree-lined edge of a playing field, which I would suggest has three characeristics:
a.) (For most people) it's pretty insignificant. That means that it's unlikely that either Google or Bing have spent much effort ensuring the correct orthorectification of images related to fairly unimportant bits of grass, or the vector shape representing their exact outline. Instead, they have probably concentrated on aligning structures and roads used for routing etc.
b.) It's non-permenent. As you can see from comparing the two satellite images, natural borders such as trees changes throughout the seasons as they grow or shed leaves, are chopped down, or more trees planted. The white lines on the football pitch may be repainted or moved. These are not good reference points to use to compare two maps, since there is a degree of subjectivity involved in mapping the outline of the feature.
c.) It's approximate and not distinct. The vector images clearly only represent an approximation of the outline drawn by the trees - they're not meant to represent it exactly. As I posted in the other thread (that I assume you or your colleague made), Open Street Map actually has a more detailed vector rendition of this area:
4.) Finally, I think you need to put this in perspective: You're looking at an image at zoom level 18, where one pixel on the screen corresponds to around 40cm along the ground. So, the magnitude of the difference you're seeing appears to be no more than 5 metres in total, say. If a difference of +/- 5m accuracy is not acceptable for your application, then I'd suggest that neither Google nor Bing Maps are suitable for you, and you're going to need to invest in a dedicated GIS system (and licence the data to go with it)
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- Marked As Answer by ByminBen Wednesday, February 01, 2012 2:39 AM
Wednesday, February 01, 2012 2:41 AM
Thanks very much for this complete answer! This issue comes from one of my customers who said his vector data doesn’t match well with the BingMaps background, after a close check we found the BingMaps and GoogleMaps doesn’t match well, which has an offset of around 5 meters. I guess BingMaps and GoogleMaps should share the same vector data source so it might be some projection differences or something else between the 2, that’s why I came here to ask.
Thanks again for your explanation, that makes sense and I really appreciate it.
Wednesday, February 01, 2012 4:12 AMOwnerIt's very unlikely the two will share vector data. The data in Bing Maps is much more accurate and has Enterprise quality data. Navteq is one of the main dat aproviders for Bing Maps. When they update a piece of data they send someone out to verify the information rather than just making the change on a computer. Simpily switching to satellite view of Google maps and it is easy to see that the vector data and the imagery data they have is mis-aligned in a large majority of their maps.
- Marked As Answer by Richard_BrundrittMicrosoft Employee, Owner Saturday, March 10, 2012 1:19 PM