# Why is polygon used as range in GIS and maps?

I am enroute to create an app that finds nearest venues. I already have another SO question on this regard.

I don't have any experience with such features, and some of the concepts are not being very obvious to me. So, I have been thinking that I am not taking things on right direction.

I have seen in number of places with both GIS and in case of mobile towers, the range is calculated in polygons. I have also been reading a bit about Haversine Formula, and it appears it does not use Polygon, it is basically two-point distance (from my understanding).

Why use Polygon for reference ? Why is circle not used for this ? How does Haversine formula integrate with this polygons concept ?

#Copied : Original question in SO as refered by Nate

• This thread is probably collecting downvotes because it seems to be based on a lack of the most basic GIS concepts - in this case the geometry types (point, line, polygon) which are explained in a GIS for beginners text. – underdark Mar 15 '13 at 6:43
• I have already pointed that out in my question `I don't have any experience with such features, and some of the concepts are not being very obvious to me. So, I have been thinking that I am not taking things on right direction.` – Kishor Kundan Mar 15 '13 at 6:54

## 2 Answers

No need to use Haversine Formula for mobile towers. The range is very small compared to earth's size, so it won't make a difference.

I'm not sure what you mean by "range in polygon". If you mean the serving areas of mobile towers, it's a Voronoi Diagram. The areas are polygons because the edges are equal-distance lines between adjacent towers. The signal can go (much) further, but the phone is looking for the closest tower.

• I'm afraid tower ranges are much more complex topic than simple Voronoi diagrams. There is load balancing an all kinds of other issues to consider. – underdark Mar 15 '13 at 7:09

You could probably get a good primer for GIS at http://www.ordnancesurvey.co.uk/oswebsite/gisfiles/index.html .