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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

Buffers are polygons drawn around a specific object at a specific distance. You can create buffers around points, polylines and polygons. The distance units used to create the buffer are the same units that the map is in.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. Click the Base(vector) layer in the Contents window to select it.
  3. Click Features | Group | Start Editing.

    Surfer must be in editing mode to access the geoprocessing command.
  4. Select the object(s) you wish to create the buffer around.
  5. Click Features | New Features | Buffer.
  6. In the Buffer dialog:

    1. Enter the Number of buffers to create. If you choose more than one, they'll be concentric with equal distances between them.
    2. Enter the Buffer distance in the same units that the map is in.
    3. Choose whether or not to combine overlapping buffer polygons. You might want to combine them if you select multiple roads or rivers, so that you get one polygon around them all instead of individual overlapping polygons.
    4. Click OK.
  1. Click Features | Group | Stop Editing. Each buffer polygon is created as a separate polygon, as seen in the Contents window. You can adjust the properties of each polygon individually to change the line or fill colors. To adjust the buffer distance, recreate the buffer.

Create buffer areas around objects at specified distances, such as concentric areas around well points, or a combined polygon around streams.

 

Range Ring

A range ring creates concentric circles of a specific radius around a selected 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 the new Base(vector) layer in the Contents window and click Start Editing.
  4. Click Features | Insert | Range Ring.
  5. Click on the map at the center location for the circle(s) and then press ESC.
  6. Right click the Base(vector) layer again and click Stop Editing.
  7. Select the Range Ring and adjust any of the settings (e.g. number of rings, radius, color, symbol and line properties, 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.

Create range rings at specific point locations. Adjust the number of rings, symbol properties, line and fill properties, or change the shape from a circle to a square.

 

 


 

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 November 13, 2018

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