I encountered this with MotionX, and now with PocketEarth. Why are GPS apps not accurate when it comes to China maps? I used OSM, Bing, Google, all same consistent errors. Either I be in Shanghai, or in some secluded cities midwest, or coastal towns, Apps like PocketEarth would give me a coordinate that is about 200 meters by 30* NW off. It is consistent which suggests that it is not a random error. Either I be in Shanghai or Xiamen, the coordinate always shows the same discrepancy.
MotionX told me that China had put a restriction on map gathering, thus maps are inaccurate. Yet GPS installed on some popular automobiles functions properly, showing the correct coordinates.
I am not sure if this is a permanent map-skewing-effort by China but, In this light, is it possible to add a feature on PocketEarth that will offset the coordinate so it will match the predownloaded map?
Thanks for letting us know about this issue! After doing some research, it appears that the GPS and maps are not aligned in *some* towns in China due to intentional skewing. GPS devices made in China for domestic use there apparently “un-skew” the GPS location fixes thus placing it correctly on the map.
I will discuss this issue with my team and try to work-around it with an offset setting or in some other way.
Additional Info: I tried to overlay my saved routes with Google Satellite and Bing Satellite maps; the coordinates matched perfectly.
But when I tried to overlay the routes with streetmaps from OSM, Bing, Google, it does not match. The discrepancy with Google streetmap is 580 meters 128* Bearing. I could not measure with OSM or Bing as I these two do not have maps on the routes I saved.