Hello,
this is an example of my problem.
I used GPS and found the longitude and latitude of a point on front of my office building.
GPS shows: N 40 00 03.26 , E 116 22 36.97
I converted to decimal data: 40.0009055, 116.376936
I used this website for converting: http://www.onlineconversion.com/map_decimaldegrees.htm
I want to find this point on the map and mark it. but there is a problem!!!!
I tried by Google Map website, Baidu Map website(chinese) and Google Earth pro Software. But they are showing different points instead of showing the point (in front of my office). the locations that they are showing are also different from each other.
Where is my mistake?
Baidu Map website:
http://api.map.baidu.com/lbsapi/getpoint/index.html
Google Map website:
https://www.google.com.hk/maps/dir/@40.0025705,116.3844989,17z/data=!4m3!1m2!3m1!2zNDDCsDAwJzA4LjEiTiAxMTbCsDIzJzM1LjUiRQ?hl=en
Could this be a projection issue with the different websites working off different projections to one another which is again different to the GPS unit?
How far off? If it is not a differential GPS then there is an accuracy of +-60m.
My first thought was coordinate system date. In the U.S. the difference between NAD1927 and NAD1983 at Latitude 30 is about 27 meters. I tried your coordinates in both of those plus World Geographic System (WGS)1966 and 1984. Every one of them plotted in exactly the same location.
@Sunil Kumar & Richard L. Shelmerdine & James A Green: Thank you so much for your answers and efforts.
the difference between Baidu (Chinese map) and google is too much. I also think its coordination issue. I should ask from my Chinese colleagues about coordination system of Baidu.
Dear respected colleagues,
I came to know about the reason of my confusion. Maybe its interesting for you also.
There is about 550 meters difference for each point between satellite view and map view of Google map (web).
For example, please check the point: 39.99978 N , 116.3882 E.
Google satellite view(web) , Google earth pro (software) and my GPS device showing same point while Google” map view” showing another place about 550 meters far (see the photo).
In the mentioned comparisons I didn’t consider Chinese map.
If you know the reason of this difference, please let me know.
And Thanks @Tilman Brock-Hesse for his useful hint and the link.
Hi!
Maybe this is caused because of different datum/projection.
If i'm not wrong, Google Maps use Mercator Projection and Google Earth Pro use an ellipsoid model of Earth (WGS84). And i don't know what projection/datum the Baidou System are using, but i know that the Baidou Constellation is not global yet (and this can mean that the system has local especifications). And there is the accurate precision issue mentioned in the answer above.
I believe this facts are affecting the location of your point.
I hope this can help you.
Best regards...
