GME

Geospatial Modelling Environment

extractedge (Extract Edge From Raster)

Creates lines along the boundary between two pixels that have different values

Description

This tool creates lines along the boundary between two pixels that have different values. It is intended to be used with categorical raster data like landcover rasters. The output polyline attribute table contains three fields that identify the cell values of the two pixels on each side of the line, and a text field that combines the two values in a single field (this is useful for identifying and displaying edges between particular combinations of values).

It is common for the output polyline data source to contain large numbers of features (because rasters tend to contain large numbers of cells and edges). This can make the output cumbersome to work with. It is recommended that you reclassify your raster (to simplify it) before running this tool so that only the edges of interest are identified in the output. This collection of tools includes a raster reclassification tool.

If you wish to simplify the output you could consider running the Dissolve command (in ArcToolbox), referencing the text field as the dissolve field. This would merge all edges of the same type into a single multipart polyline feature, thereby greatly reducing the number of records in the table.

Although a 'band' option is included so that users can identify which band to process in the case of multiband images, it is recommended that you do not run this tool with continuous raster data (like DEM's, or unclassified satellite imagery). This would result in the creation of edges at almost every cell boundary.

Syntax

extractedge(in, out, [band]);

inthe input integer raster data source
outthe output line data source
[band]the input band (default=1)

Example

extractedge(in="C:\data\landcov", out="C:\data\lcov_edges.shp");


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