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How can I draw a circle on a map with a specific radius and center point?

You can create a circle of a specific radius around a point by using the Buffer command or by drawing a Range Ring.
 
Buffer

A buffer is a polygon around an specific object at a specific distance. To create a buffer polygon around a point in a map:

  1. The first step is to create the point in a base layer. If you already have a base layer with the point in it, you can skip this step. If you do not, you can follow the steps in this KB article to add points in the map.
  2. Once the point is added as part of a base layer, then you can create a buffer around it at a specific distance. In the Contents window, right click over the Base layer that the point is in, and click Edit Group.
  3. Select the point and click Features | New Features | Buffer.
  4. Set the Buffer distance to the circle's radius, in map units.
  5. Click OK and the circular polygon is created.

Range Ring

A range ring creates a circle of a specific radius around a specific point location. To create a range ring in a map:

  1. Select the existing map.
  2. Click Home | Add to Map | Layer | Empty Base.
  3. Right click over the new Base layer in the Contents window and click Edit Group.
  4. Click Home | Insert | Range Ring and click on the map at the center location for the circle.
  5. Right click over the Base layer again and click Stop Editing Group.
  6. Select the range ring and adjust any of the settings (e.g. number of rings, radius, fill colors, etc) in the Properties window. The radius value is in map units, so if your map is in UTM coordinates (meters), then the radius value is also in meters.

 

If you are using Surfer 12 or previous, you can use the attached Excel XLSX file to calculate the coordinates around the circle, which you can use to create a BLN file and load as a base map. To use the attached XLSX file:

  1. Open the Excel file.
  2. Enter in the X and Y coordinates of the center of the circle in cells B1 (X) and C1 (Y).
  3. Enter the radius of the circle in cell B2.
  4. Copy the all the cells highlighted in yellow
  5. Open Notepad and click Edit | Paste.
  6. Click File | Save As in Notepad and save to a BLN file by entering the filename and extension in quotes (e.g. "circleshape.bln") and clicking Save.
  7. You can add the circle to the map by selecting the existing map in Surfer and clicking Map | Add | Base Layer, selecting the BLN file and clicking Open.

 

Updated September 26, 2017

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