Hi HN!I am asking for your guidance again.The problem:
In Subsaharan Africa, maps are unreliable and/or unavailable. 
Excluding city centers, there are no addresses, street names or the likes.The context: 
I was shocked by the smartphone penetration. Everyone has at least one smartphone with GPS/Camera and Whatsapp/email  (Thanks India & China). The 4g/LTE service is reliable & cheap.The idea:
With a relatively young population and a low cost of living, I  can afford to pay people to crowdsource streets, homes, shops, etc...
Thus I am building an android app for that.
Taking a picture of every door you see
Mapping roads with the user GPS
Adding elements such as road condition/infrastructureThe question:
How would you advise me to build such a service? 
Should I ask the user to open the app while he is moving, and taking pictures of every door he sees? Then add it to a map? 
How can I generate an accurate map from hundreds of user travel histories and geo-tagged pictures?
I'm gladly receiving every piece of adviceMy knowledge:
I owned mobility as a service Saas B2G company in rural Canada called Proxybus. I have worked with OSM (OpenStreetMaps), and I'm a fairly skilled full-stack developer.