GENPT

 

generates regularly or randomly distributed points within the features in an existing polygon coverage.

__________________________________________________________________________

 

GENPT <in_cover> <out_cover> <DENSITY <number> | NUMBER <number>> {POLY | BND} {REGULAR | RANDOM | STRATIFIED <size>}

 

ARGUMENTS

 

<in_cover> - the input polygon coverage that contains the POLYgons or BND within which the points will be generated.

 

This coverage must have map units of METERS or FEET.

 

<out_cover> - the name for the output point coverage.

 

<DENSITY <number> | NUMBER <number>> - this argument specifies how many points to generate.

 

<DENSITY <number>> - DENSITY is a keyword indicating that the number of points to be generated will be specified based on density.  <number> is the number of points to be generated per square mile.

 

<NUMBER <number>> - NUMBER is a keyword indicating that the number of points to be generated will be specified based on one total number.  <number> is the total number of points to be generated.

 

When specifying a total NUMBER of points, this <number> will only be exact when using the RANDOM method for generating points.  When using the REGULAR or STRATIFIED methods the total number of points will approximate the specified <number>, but will likely be different depending on how the grid of points lines up with the {POLY | BND} of the <in_cover>.  If you want an exact number of points generated using the REGULAR or STRATIFIED methods, then you may need to increase the <number> slightly and eliminate extra the points after running GENPT.

 

{POLY | BND} - the extent of the area within which the points are generated.

 

POLY - the points are generated within the boundaries of the polygons in the <in_cover>.  This is the default.

 

BND - the points are generated within the minimum bounding rectangle (BND) of the <in_cover>.

 

{REGULAR | RANDOM | STRATIFIED <size>} - how the points are to be distributed.

 

REGULAR - the points are distributed regularly, one at the center of each cell in a grid whose origin is the map coordinate 0,0.  The size of each cell is determined by the <DENSITY | NUMBER> of points specified.  This is the default.

 

RANDOM - the points are distributed randomly.

 

STRATIFIED <size> - the points are distributed randomly within a regular grid of cells.  The <size> of each cell in the grid is specified in square miles.  The number of points generated within each cell is determined by the <DENSITY | NUMBER> of points specified.  For example, if a DENSITY of 5 points per square mile is specified and the STRATIFIED method is used with a <size> of 10 square miles, then 50 points (5 * 10) will be generated per grid cell.  The origin of the grid is map coordinate 0,0.

 

 

NOTES

 

GENPT runs from the ARC module of ArcInfo.

 

 

EXAMPLES

 

Arc: &run genpt usage

Usage: GENPT <in_cover> <out_cover> <DENSITY <number> | NUMBER <number>> {POLY | BND} {REGULAR | RANDOM | STRATIFIED <size>}

 

1)  To generate a regular distribution of points, one every square mile within the polygons in a vegetation coverage:

 

Arc: &run genpt veg_cover point_cover DENSITY 1

 

2)  To generate 100 randomly distributed points within the polygons in the vegetation coverage:

 

Arc: &run genpt veg_cover point_cover NUMBER 100 # RANDOM

 

3)  To randomly generate 50 points per every 10 square miles within the BND of the vegetation coverage:

 

Arc: &run genpt veg_cover point_cover DENSITY 5 BND STRATIFIED 10