Catchment areas can be precisely defined using kilometer specifications. Suppose you'd like to create catchment areas of 40 kilometers around the German cities of Düsseldorf and Cologne, and then determine the areas of overlap.

Note: In RegioGraph versions 8 and higher, the Create Circles command in the Map menu automatically generates catchment areas around locations.

Step 1: Preparations

Display cities with more than 100,000 inhabitants and the country's regional borders on a worksheet.

Use Map > Zoom + to magnify the area around North Rhine-Westphalia, the German federal state in which Düsseldorf and Cologne are located.

Step 2: Drawing a circle

Create a new, empty layer for any desired objects in the Layer Control window by using the right mouse button.

Select Insert > Ellipse. While pressing and holding SHIFT, draw a circle on the map. The radius of the circle is displayed in the status tab at the bottom of the screen.

Set the color of the circle to transparent by selecting Format >Colour Selection>Transparent.

Step 3: Positioning the circle correctly and determining its size

Switch to the cities > 100,000 layer in the Layer Control window. Click on the symbol for Düsseldorf using the right mouse button. Select Properties from the context menu. Click on Size+Position. Note the latitude and longitude coordinates for Düsseldorf. 

Close the window and switch to the Object layer in the Layer Control window.
Right-click on the circle object. Click on Properties in the context menu, then on Size+Position. Enter "40" for both the height and width, and the coordinates of Düsseldorf for the center point position.