If you are using live locations (for example ViewRanger Buddybeacons etc) and then upload a detailed gpx file, you need to be slightly cautious that the data sources are in-sync and compatible. Differences in altitude (different apps calculate altitude differently, and if the source has no altitude data - Social Hiking uses an estimate based on satellite data via Geonames) or timestamp (some sources use your device time, others use the time according to satellites, and others use the receiving server's time) can cause issues with your map.
These issues can be seen in Social Hiking as very inaccurate distance or height gain, often with obvious spikes in the altitude graph (see example below) or in the worst cases, visual spikes on the map itself.
These problems can also occur if you are using multiple live location sources, but usually have much less of an effect.
If these problems occur, the solution is to import your gpx file overwriting existing data - during the import process, Social Hiking will remove any existing locations before importing the new data (NB any media is retained and re-linked to the new data).
Unfortunately, depending on the live source you use, the old live locations may get re-imported - sources like SPOT are feeds, so your last few (30-50) locations are constantly checked and reimported if deleted. As a workaround to ViewRanger's feature / bug of sending new location data in reverse order, the last 8 hours of locations since your last position are constantly checked and reimported if deleted.
The solution to this is to suppress your live location data before you import the gpx file - those positions will then not get reimported. However, please note that those locations will permanently be suppressed from your map - depending on your update rate, this may create gaps in the your map.
For more information on deleting or suppressing locations (and the difference) - see http://www.shareyouradventure.com/blog/2013/03/09/the-case-of-the-reappearing-location-data-or-delete-vs-suppress/
Fixing the issue after uploading a gpx file
If you find you have issues as above after uploading a gpx file, the process is:
- delete (not suppress) all locations for the map you are having problems with
- wait for any live locations to reimport (at least 20 minutes depending on the source)
- suppress the live locations
- reimport the gpx file