NAME: Radiating Lines and Points v. 1.1 (Click Name to Download)
Last modified: March 7, 2006
TOPICS: ArcView 3.x, radiating, radiate, origin, center, sample, sampling, point, compass, bearing, azimuth, View, Analysis, Tools
AUTHOR: Jeff Jenness
DESCRIPTION: This extension generates either or both of two separate shapefiles: 1) A polyline shapefile of a set of lines radiating outward from each of a set if Input points, and 2) A point shapefile of the endpoints of those lines. This is a useful function for those who need to know the locations of a series of regularly-spaced points surrounding input points, or for those who need radiating lines extending outward at regular intervals from an origin point. This is an especially useful function for determining sampling points around a point of interest.
All or only selected records: You can either use all the points in the point theme for the analysis or only a selected subset of points. If any points in your theme are selected, then only those selected points in that theme will be used in the analysis. If no points in your theme are selected, then all points in that theme will be used in the analysis.
Results: Upon completion, you will have one or both of the following depending on your choice:
REQUIRES: This extension requires a Point theme with Point ID values to be present in the view.
This extension also requires that the file "avdlog.dll" be present in the ArcView/BIN32 directory (or $AVBIN/avdlog.dll) and that the Dialog Designer extension be located in your ArcView/ext32 directory, which they usually are if you're running AV 3.1 or better. The Dialog Designer doesn't have to be loaded; it just has to be available.
Version 1.1 (March 7, 2006) adds options to randomize the first bearing, and extends the function to input both PointZ and PointM shapefiles.
Recommended Citation Format: For those who wish to cite this extension, the author recommends something similar to:
Jenness, J. 2006. Radiating Lines and Points (rad_lines.avx) Extension for ArcView 3.x, v. 1.1. Jenness Enterprises. Available at: http://www.jennessent.com/arcview/radiating_lines.htm.
Please let me know if you cite this extension in a publication (email@example.com). I will update the citation list to include any publications that I am told about.
This software has been cited by:
Ekebom, J., P. Laihonen, and T. Suominen. 2003. A GIS-based step-wise procedure for assessing physical exposure in fragmented archipelagos. Estuarine, Coastal and Shelf Science. Elsevier Ltd. 57:887-898.
Begin by placing the "rad_lines.avx" file into the
ArcView extensions directory (../../Av_gis30/Arcview/ext32/).
2) After starting ArcView, load the extension by clicking on File
, scrolling down through the list of available extensions,
and then clicking on the checkbox next to the extension called
4) From your View toolbar, click on the icon. This brings up the Input Theme dialog box:
The Point Theme list contains all the Point themes from your view. When you select the one you want, then the ID Field list will fill up with all the non-shape fields from that point theme. Select the field that contains the ID values of each point.
Next, enter the number of radiating lines or the bearing interval you want. You only need to enter one of these values; as you enter data in one box, the other box will fill with the appropriate conversion. In the above example, 13 radiating lines distributed evenly around the point means a bearing interval of 27.6923 degrees.
Next, enter the line length in map units. These are the units of your actual data, so if your view is projected then you might want to project your points before running this extension.
You can set the first bearing to go in a random direction by checking the “Randomize First Bearing” checkbox. Otherwise the first bearing will point due North (0 degrees). The rest of the lines will be generated in regular angular intervals proceeding clockwise around the compass.
Finally, select the output you want. You can generate either a Polyline shapefile of the radiating lines or a Point shapefile of the endpoints, or both. The feature attribute tables for these shapefiles include the following fields:
Polyline Feature Attribute Table:
Point Feature Attribute Table:
6) Specify Hard Drive Locations to save your Shapefiles: You will be prompted to specify a location on the hard drive to save your desired shapefiles. These are standard ArcView Dialog Boxes and should be familiar to most users. These files are permanent and will not be deleted when ArcView is shut down.
Enjoy! Please contact the author if you have problems or find bugs.
Jeff Jenness firstname.lastname@example.org
3020 N. Schevene Blvd.
Flagstaff, AZ 86004
Please visit Jenness Enterprises ArcView Extensions site for more ArcView Extensions and other software by the author. We also offer customized ArcView-based GIS consultation services to help you meet your specific data analysis and application development needs.