Pitney Bowes MapInfo Professional - Manual (Page 294)

• Concentric ring buffers allow you to create circles around map object(s) or point(s) and compute
aggregated values for underlying data that occur within each ring. You would use concentric ring
buffers to determine the number of customers within a certain radius of a store or other location.
• Convex hull buffers create a region object that represents a polygon based on the nodes from the
input object. You can think of the convex hull polygon as an operator which places a rubber band
around all of the points. It will consist of the minimum number of points so that all points lie on or inside
the polygon. With convex hull buffers, no inside angle is greater than 180 degrees.
For specific instructions, see Specifying Buffer Calculations in the Help System.
Concentric Ring Buffers
In the Creating a Buffer , you learned how to create a buffer around one or more objects. Concentric
ring buffers allow you to create multiple buffers of different width (radii) around an object or a set of
selected objects. The Concentric Ring Buffer tool can assist you in creating this type of buffer.
• For specific access instructions, see Concentric Ring Buffer Tool in the Help System.
To create concentric ring buffers:
1. In the Map window, select the object(s) you want to place buffers around.
2. On the Tools menu, point to Concentric Ring Buffers and click Create Concentric Ring Buffers.
The Concentric Ring Buffers dialog box displays.
3. To add a ring, specify the radius in the Radius field and click Add Ring. Continue this until you have
added all of the rings you want from the smallest to largest.
4. Select the units of each radius in the Units drop-down list.
5. To set the smoothness of the ring buffer, type a number between 3 and 500 in the Smoothness
field. The larger the number, the smoother and less jagged the curves of the ring.
6. Type the table name and select the path in which you want to store this buffer information. MapInfo
Professional stores the concentric ring buffer information into this table including the columns
containing the ring number, radius value, radius units, area, and area units for each ring.
7. When you have finished the buffer settings, click OK.
Use the Modify Ring and Delete Ring buttons to change the ring settings, or click Clear All to start all
over and create new concentric rings. To change the style of a buffer ring, select it in the Buffer Radii
MapInfo Professional 12.5 294
Buffering Your Data