title: Geopoints: From Single Coordinate to Bounds on map
body: <p>I try to figure out how to come from a single given coordinate (lat/lon) to the nearest bounds which enclose this coordinate on a map e.g. streets or sea. 
  Here two examples to give you a better understanding of what I mean:</p>
  
  <p><a href="https://i.stack.imgur.com/dEUyx.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dEUyx.jpg" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/6b3ys.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6b3ys.jpg" alt="enter image description here"></a></p>
  
  <p>What i tried already or thought about:</p>
  
  <ol>
  <li>Setting up a Nominatim server and search for the given coordinate via the reverse-function to get the bbox and/or the geojson polygon of this coordinate. -> this only works when the given coordinate is within a POI or for example directly on a street.</li>
  <li>Writing an algorithm to walk in all 4 or 8 directions (n/e/s/w) and 'stop' when the map layer/surface changes (change = stop for this direction and mark a bounding-point)</li>
  <li>Building up an image-recognition system using TensorFlow to detect the different colors and 'draw' the polygon. Worked with TensorFlow a couple of times but this seems to be the most tricky solution to implement (but at my current understanding the most precise one)</li>
  </ol>
  
  <p>Does someone of you have any other ideas to get a solution for this problem? Would appreciate any kind of approaches</p>
  
  <p>Cheers!</p>