I'd like to draw an area around a certain point. I don't want a simple circle of 800 meters diameter, but a shape that is the result of the endpoints of lines, starting at my point and following all the roads it can find for 400 metres.

My available data is QGIS in version 2.14.13, a csv layer with those points and all kind of OSM layers.

I tried the approach to 1) label the points incl a background image and to 2) draw a larger icon with 800 map units in diameter (see Image).enter image description here That is roughly ok but not what I want it to be in the end

Any idea how to do that? I guess that I'd need to have the streets as a vector layer, so I would have to extract them within the are of 400 meters around my points, right?

  • Could you elaborate on what you are trying to achieve, please? A picture of your data with some annotations or markups would probably help to understand your question. – Nightwatch Nov 10 '17 at 11:34
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  • Edited the question. – Guido Gallenkamp Nov 14 '17 at 9:59

If you are looking for a network analysis (using your roads, OD matrice), you could make an isochronal map (now available in QGIS 2.99)

If you only want extract the endpoints using an euclidiean distance (buffer), I propose to do this :

  1. Create a shapefile containing the start_point (origin)
  2. Do a simple buffer from this point (distance = 800m)
  3. Extract by a spatial query the features that are within the circle
  4. Add the spatial query result to your map (temporary file)
  5. Use the v.to.points tool (processing toolbox) without any change
  6. Your points are created into a temporary file (default)

Be careful : you will get as many points as lines found at the start point.

I hope it's gonna be ok...

  • Thank you for the approach. If I enter 800m distance, I get a fullscreen colored layer. I chose my points layer as source, chose the buffer from the geoprocessing toos and entered the number. Didnt work. The currently published QGIS version is 2.18.14 - what is the 2.99 about? – Guido Gallenkamp Nov 14 '17 at 11:20
  • Your version is a good version, no problem about that. I think you're not following the differents steps I proposed. Your buffer must be a 800m radius circle, no more. If you zoom out, you must see your circle. If your radius circle is not correct, check your projection, It may be the problem you have. Good luck ! – Keiko Nov 14 '17 at 14:59
  • I already have a shape file, containing 48 starting points. When I open the vector layer -> geoprocessing ->buffer menu, I have more options than just "distance". – Guido Gallenkamp Nov 15 '17 at 10:00
  • "Buffer distance" = 800m; the other parameters can stay by default exept if you want : make your buffer from specific points (check only selected features), make your buffer with differents distances (Buffer distance by a field), make as many buffer as points (dissolve buffer results). – Keiko Nov 15 '17 at 10:41

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