HDMapper™ ShapeMaker Squares and Circles
Q: How can I add a 10-mile radius circle to my coverage map?
A: With TAP6.0.2224 or later and a Maintenance Subscription date of February 28, 2008, or later, you can use the ShapeMaker function to draw a circle or a square centered on a location.
With TAP6.0.2376 or later and a Maintenance Subscription date of February 28, 2011, or later, you can draw segmented circles with the ShapeMaker function.
Note that all values in this example are for demonstration purposes only. You should determine appropriate settings for your application.
The ShapeMaker function in HDMapper enables you to draw points, lines, or polygons on the map. You can enter specific coordinates (such as the end points of lines, or vertices of a polygon) or you can draw by clicking on the map. The feature described in this article enables you to specify center coordinates and a distance, and then to draw a circle with that radius or a square with that distance from the center site.
For example, suppose you have a coverage map drawn as shown:
Click on the “Create Drawing Layer” button to open ShapeMaker.
Select the type “Polygon” and click the Continue button.
Select the folder where you want to save the shapefile and specify a name for the file:
ShapeMaker creates a shapefile (or adds to an existing polygon shapefile) to store the drawing objects you create.
Note that shapefiles can contain only one object type: points, lines, or symbols. You cannot, for example, add a circle (polygon) object to a shapefile that was created to hold lines.
It is strongly recommended that you only add ShapeMaker objects to files you create, or to copies of other shapefiles.
The ShapeMaker form is displayed. Note the two new buttons for creating circles and squares.
For detailed information on other uses of ShapeMaker see the ShapeMaker article.
As an example, to draw a 10km circle around the transmitter site, click the Circle button
To get coordinates from the Fixed Facility database, click the button:
Use the Fixed Facility database interface to select the facility you want to use as the center of the circle:
Click the Continue button.
The facility coordinates are returned to the Circle Shape form:
Select the units and set the distance you want for the radius of the circle:
Set the arc value (an arc of 1 degree will draw the circle as a polygon with 360 vertices; 10-degree arc will draw 36 vertex locations, etc.):
Click the Draw button to add the shape to the Polygon Points form:
Note that a preview line showing the shape is displayed on the map.
To save the shape to the user layer shapefile, click the Save button:
You will be prompted for a description of the shapefile object:
The shapefile will be added to the legend, and the object shown on the map:
Because HDMapper uses shapefiles with latitude-longitude coordinates, the circle will appear as an ellipse. See the section below about exporting to Google Earth.
You can double-click the new layer legend entry to change the layer properties:
You can also select a center point by clicking on the map. For example, suppose you want to draw a square extending 10 miles from a highway intersection.
As before, click the Draw button on the HDMapper toolbar:
Select Polygon as the type of shapefile:
You can select the same file name to add the new object to:
If you select the same shapefile, a warning will be displayed:
Since the shapefile is currently open and a part of the drawing, you must close the file and remove it temporarily from the map to add the new object.
You can also cancel the operation and specify a different file name to use.
Remember that the shapefiles are treated as layers, so all the objects in a layer (a single file) will have the same properties, such as color and fill type. If you want to specify different colors or other properties for different objects you create, you should specify different file names.
For this example, click the OK button to use the same file.
Another warning will be displayed, alerting you to the fact that you are adding new shapes to an existing file.
Click the OK button to add the new shape to the existing file.
Now click the Square button on the Polygon Points form:
To select the point on the map (in this example a highway intersection), click the “Point from Map” button:
The yellow prompt is displayed to click the center point.
(If you have the exact coordinates of the highway intersection you could enter them in the boxes on the Square form.)
Select the units and set the distance you want to draw from the center point:
Click the Draw button to create the object vertex points:
Click the Save. You will be prompted to enter a description for the new object:
When you click OK to save the new description the program will add the square to the shapefile and load the shapefile into the map:
As before, you can change the layer properties. Since the new objects are in a shapefile, you can use the other functions in HDMapper, such as the label button:
You can also export the map with the shapes to Google Earth.
You may want to hide other layers (unless you want that information also to be included on the Google Earth export):
Then click the Google Earth export button.
The visible layers (including the square and circle shapefile in this example) will be exported and loaded into Google Earth.
Note that in the map projection presentation used in Google Earth, the aspect ratio of the shapes is corrected.
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Copyright 2008 by SoftWright LLC