GeoProcessor / Command / ClipGeoLayer

Overview
Command Editor
Command Syntax
Examples
Troubleshooting
See Also

Overview

The ClipGeoLayer command clips an input GeoLayer by a second GeoLayer, the clipping GeoLayer.

The output is a new GeoLayer containing the features within the input GeoLayer that intersect the features of the clipping GeoLayer.
The output GeoLayer retains the attribute fields and values of the input GeoLayer.
The output GeoLayer retains the coordinate reference system of the input GeoLayer.
The input GeoLayer and the clipping GeoLayer must be projected in the same coordinate reference system.
The input GeoLayer can have one or more features with any geometry (point, line or polygon).
The clipping GeoLayer can have one or more features but those features must be polygons.

Command Editor

The following dialog is used to edit the command and illustrates the command syntax.

ClipGeoLayer Command Editor (see full-size image)

Command Syntax

The command syntax is as follows:

ClipGeoLayer(Parameter="Value",...)

Command Parameters

Parameter	Description	Default
`InputGeoLayerID` required	The ID of the input GeoLayer.	None - must be specified.
`ClippingGeoLayerID` required	The ID of the clipping GeoLayer. The clipping GeoLayer must be contain polygon geometry.	None - must be specified.
`OutputGeoLayerID`	A GeoLayer identifier for the output GeoLayer. Refer to documentation for best practices on naming GeoLayer identifiers.	`InputGeoLayerID` `_clippedBy_` `ClippingGeoLayerID`
`Name`	Name of the output GeoLayer.	`OutputGeoLayerID`
`Description`	Description for the output GeoLayer.
`IfGeoLayerIDExists`	The action that occurs if the `OutputGeoLayerID` already exists within the GeoProcessor: `Replace` - The existing GeoLayer within the GeoProcessor is relaced with the new GeoLayer. No warning is logged. `ReplaceAndWarn` - The existing GeoLayer within the GeoProcessor is replaced with the new GeoLayer. A warning is logged. `Warn` - The ClipGeoLayer command does not run. A warning is logged. `Fail` - The ClipGeoLayer command does not run. A fail message is logged.	`Replace`

Examples

See the automated tests.

The following GeoLayer data are used in the examples. The examples assume that the floodplains-FEMA-CO-4326 and countyBoundary-CDOT-Park-4326 GeoLayers have already been read into the GeoProcessor with the ReadGeoLayerFromGeoJSON command.

Example GeoLayer Data

GeoLayer ID	Description	Image
`floodplains-FEMA-CO-4326`	Colorado floodplains provided by the Federal Emergency Management Agency (FEMA). Projected in WGS84 (EPSG:4326).
`countyBoundary-CDOT-Park-4326`	Park County Boundary provided by the Colorado Department of Transportation (CDOT). Projected in WGS84 (EPSG:4326).

Example 1: Clip a GeoLayer

ClipGeoLayer(InputGeoLayerID = "floodplains-FEMA-CO-4326", ClippingGeoLayerID = "countyBoundary-CDOT-Park-4326")

After running the command, the following GeoLayer IDs are registered within the GeoProcessor.

GeoLayer ID	Description	Image
`floodplains-FEMA-CO-4326`	The input GeoLayer. Colorado floodplains provided by FEMA. Projected in WGS84 (EPSG:4326).
`countyBoundary-CDOT-Park-4326`	The clipping GeoLayer. Park County Boundary provided by CDOT. Projected in WGS84 (EPSG:4326).
`floodplains-FEMA-CO-4326_clippedBy_countyBoundary-CDOT-Park-4326`	The output (clipped) GeoLayer. Park County floodplains provided by FEMA. Projected in WGS84 (EPSG:4326).

Below is an image of the input and output products of the ClipGeoLayer command.

The top image shows the Colorado floodplains layer (input GeoLayer) with the outline of the Park County Boundary layer (clipping GeoLayer).
The bottom image shows the Park County floodplains layer (output clipped GeoLayer) with the outline of the Park County Boundary layer.

Example 2: Assign a Unique GeoLayer ID to the Output

In Example 1, the ClipGeoLayer command clipped the Colorado floodplain layer to the Park country boundary layer. The default output GeoLayerID, however, is quite long and does not follow the GeoLayer ID best practices. In this example, the same ClipGeoLayer command user the OutputGeoLayerID parameter to specify the GeoLayer ID for hte new output GeoLayer.

ClipGeoLayer(InputGeoLayerID = "floodplains-FEMA-CO-4326", ClippingGeoLayerID = "countyBoundary-CDOT-Park-4326", OutputGeoLayerID = "floodplains-FEMA-Park-4326")