Originally Posted by
njkayaker
Most of Google's map data is from Google. Most commercial companies provide ways for the public to provide corrections.
It appears that Openstreetmap (OSM) is the largest (by far) crowd-sourced map database and, at least in the US, it started with a huge amount of publicly-funded (governmental) data. I suspect that's true for Africa too. (And editing OSM data is assisted, in important ways, by commercial companies, such as Bing, and governments).
Regardless, there are many places where the OSM maps are the best available. From what I've experienced (mostly in the US and some in Germany), my opinion is that the OSM maps are very good. But, in areas well covered by commercial firms, the commercial maps are more complete and accurate. There are, more often than one might expect, fairly major things missing or wrong on the OSM maps (I know because I fix them!)
Still, I like the OSM maps (well enough to take the effort make them better). But they aren't perfect.
None of this is meant to discourage people from using OSM (in some cases, you might not have a choice) but to make sure people's expectations are realistic.
I agree that OpenStreetMap is very good. I use OSM and also edit it so the areas I ride most are up to date. It's not perfect but nothing is I'v never found a map without mistakes plus things change. I'm happier with it then with the Garmin maps. A Garmin GPS will route on bike paths with OSM but not with a Garmin map. I mostly ride road but sometimes a bike path can be a good shortcut, also some of the Brevets I do use some bike trails. If I find an error I can fix it and have an update fast and free. I have found errors on Garmin maps and reported them. They update maps 4 times a year so depending on timing it could be 3+ months for the correction to make it to the map. I must then buy a new map to get the update. I have Garmin maps on my GPS so if I'm in an area I think they are better than OSM I can switch to it.