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#1 2018-11-08 15:22:12

herrentorte
New Member
Registered: 2018-11-08
Posts: 2

Have a map generate list of POIs within a radius of any given point???

Hi everyone,

first of all let me make a disclaimer that I am completely new to the whole programming. I have done a little bit of HTML in the past and that's about it.

Now, what I want to create is a map (ideally offline) into which I can import a large number of street addresses as points of interests. So far so good. Finally, once I have imported all those addresses, I want to be able to click anywhere in the map (or enter an address) and have all previously imported POIs which are within a specified radius around where I clicked read out and exported into a list (e.g. a csv file).

As I am not sure if I have described what I mean very well, I will explain the end result I have in mind one more time. I imagine a tool similar to Google Maps (preferrably offline, but that's not super important). Into this map I will have imported a bunch (I am thinking a few thousand) of addresses, spread out accross the entire country. I then want to be able to specify one point on this map plus a radius of, say, 20 miles, and have the tool generate a list of all addresses (which I have imported previously) within 20 miles of the point I specified.

A few issues I have are, how can I "conveniently" import thousands of addresses from an Excel file into an open-source map. I am fine with copy and paste but I can't look up the GPS coordinates for each individual address. So the open-source map I use would have to "know" what point on the map the street addresses are referring to.
Secondly, I know there are websites that let me draw a circle of a specified radius around any given point on a map. So I presume this part won't be too difficult. But I have no idea what I can to about the next step of having those addresses exported into a list.

Any pointers and advice as to what tools or code I could use will be greatly appreciated.

Thank you very much!

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#2 2018-11-08 16:01:21

hadw
Member
Registered: 2014-09-02
Posts: 1,081

Re: Have a map generate list of POIs within a radius of any given point???

Do you want all street addresses known to the open database map, or just those that are also in your list of addresses?

The former is theoretically straightforward, but may involve your downloading the complete database for the country in question.

I suspect the latter requires a local installation of Nominatim.

Don't forget that your circle is being plotted on a sphere, so you will have some trig to do.

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#3 2018-11-09 10:13:39

herrentorte
New Member
Registered: 2018-11-08
Posts: 2

Re: Have a map generate list of POIs within a radius of any given point???

Thank you for you reply, hadw. I meant the latter. I want just the addresses from my list within that radius.

As of yet, I know neither what Nominatim is nor what a trig is. But it's something for me to investigate, so thanks for the pointers.

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#4 2018-11-09 11:36:44

hadw
Member
Registered: 2014-09-02
Posts: 1,081

Re: Have a map generate list of POIs within a radius of any given point???

Nominatim is the most commonly used geocoder/reverse geocoder in the OSM ecosystem.  It is what you would use to look up an individual address and try and find a corresponding OSM object.  What I don't know is whether there is any acceptable way of using it on large numbers of addresses as a batch.

trig is a popular contraction of trigonometry, In this case, spherical trigonometry.

Google would have answered both of these questions.

Also be aware that in most places, individual property addresses have not been added by OSM mappers, and, also not even address interpolations have been added.  Also note that even Google and Bing rely heavily on address interpolation, so can give significantly wrong locations if properties are not evenly distributed along the whole length of the street.  (On the other hand, for most real life applications, the great circle distance is not a useful measure or how far away something is, so it may not matter that properties are placed the wrong side of your boundary.

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