CRCENTROID

Description

CRCENTROID is a vector and thematic raster operation that generates a point location (x-coordinate and y-coordinate) for each shape or pixel value in the input layer.

Parameters

Name	Type	Caption	Length	Value range
FILI *	String	Input file name	1 - 192
FILO	String	Output file name	0 - 192
DBVS	Integer	Input vector segment	0 - 1
DBIC	Integer	Input raster channel	0 - 1
SRCATTR	String	Source attributes	0 - 4	COPY, JOIN Default: COPY
CENTROID	String	Generate centroids for (polygons only or all shapes)	0 - 8	Default: Polygons
REPORT	String	Report mode	0 - 192	Quick links
MONITOR	String	Monitor mode	0 - 3	ON, OFF Default: ON

* Required parameter

Parameter descriptions

FILI

Specifies the name of the file that contains the input vector or thematic raster data from which the centroids will be generated.

FILO

Specifies the name of the PCIDSK image file that receives the point layer (centroids) generated from the input layer.

FILO is created if it does not already exist.

DBVS

Specifies the segment that contains the vectors for which the centroid layer will be constructed. If DBVS is not specified, DBIC must be specified.

DBIC

Specifies the thematic raster channel that contains the image for which the centroid layer will be constructed. If DBIC is not specified, DBVS must be specified.

SRCATTR

Specifies whether the attributes from the source layer are copied or joined to the point (centroid) layer.

CENTROID

Specifies whether the centroid is to be generated for polygons only or for all shapes. This parameter is only used when the input is a vector layer.

Valid values are: POLYGONS or ALL. If this parameter is unspecified, the centroid is generated by default for polygons only.

REPORT

Specifies where to direct the generated report.

Available options are:

• TERM: generates a report on the terminal (default)
• DISK: generates a report on file "IMPRPT.LST"
• OFF: turns off report generation
• <filename>: appends a report to the specified file

MONITOR

The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.

Available options are:

• ON: Turns the monitor ON (default)
• OFF: Turns the monitor OFF (recommended if running in batch or background mode)

Details

CRCENTROID generates centroids from a vector layer or thematic raster layer.

For vector layers, CRCENTROID creates centroids for polygons only or for all shapes in the layer. If the shape is a point, the resulting centroid is the same as the point. If the shape is a line, the resulting centroid is a point at the center of the line (not necessarily on a vertex of the shape). The generated coordinates are of the same projection as the input polygon layer. The point layer has only one attribute, which is the shape ID of the shape from which the point is generated. The attributes of the source shape are joined or copied to the corresponding point in the point layer.

For thematic rasters, a point is generated for each attribute record. The centroid is contained in the biggest contiguous area. If you want a centroid for each contiguous area of pixels, use RAS2PNT.

Example

The following example creates a centroid layer in the output file based on thematic raster 2 in the combined1.pix file.

EASI>FILI = "combined1.pix"	! Specifies the input file name.
EASI>FILO = "output.pix"
EASI>DBVS =			! Uses DBIC.
EASI>DBIC = 2			! Uses channel 2.
EASI>SRCATTR =			! Uses "COPY" by default.
EASI>CENTROID =		! Uses "Polygons" by default.
EASI>REPORT =
EASI>MONITOR  =
EASI>run CRCENTROID