2 Replies Latest reply on Oct 4, 2018 8:24 AM by Ken Flerlage

# User-defined radius circles around multiple points on a map

Hi all,

I am struggling to create user-defined radius circles around multiple points on a map:

Here I have created a map plotting points based on given latitude and longitude numbers:

I would like to create a parameter which allows me to toggle the size of each mark so I am able to zoom into each Local Authority using the Filter already created and then for all the marks available on the map, create a circle around the mark with a parameter-given radius (eg. 0.5km or 5km)?

I have seen Richard Leek's work on concentric circles as well as the Knowledge Base available on Measuring Distances between locations on a map etc. however all these are based on single map locations and are more complex that I had in mind. The end result would look like this:

I understand this would involve Dragging an Integer-Range Parameter to the Size Mark Card however I am unsure how to make this related to distance (I also understand the Trigonometry required to link Latitude and Longitude to Distance). I am using Tableau 2018.1.

Thanks for your help!

Regards

Neel

• ###### 1. Re: User-defined radius circles around multiple points on a map

Neel,

I'm not sure if this is too far afield from your project,

but just wanted to pass along this thread:

• ###### 2. Re: User-defined radius circles around multiple points on a map

Here's a way to do it with SQL Server's spatial features: https://vizpainter.com/draw-circles-exact-distance-radius-maps-tableau/

But if you don't have that, then you're going to have to calculate your radius in terms of latitude/longitude degrees. Then you'll need to actually draw the circles using polygons and a bit of trig (you can't use a circle shape because you can't fix the size).