com.esri.arcgis.geoprocessing.tools.spatialanalysttools
Class FlowDirection

java.lang.Object
  com.esri.arcgis.geoprocessing.AbstractGPTool
      com.esri.arcgis.geoprocessing.tools.spatialanalysttools.FlowDirection

All Implemented Interfaces:

GPTool

public class FlowDirection
extends AbstractGPTool

Creates a raster of flow direction from each cell to its steepest downslope neighbor. The Flow Direction tool is contained in the Spatial Analyst Tools tool box.

Usage tips:

• The output of the Flow Direction tool is an integer raster whose values range from 1 to 255. The values for each direction from the center are:For example, if the direction of steepest drop was to the left of the current processing cell, its flow direction would be coded as 16.
• If a cell is lower than its eight neighbors, that cell is given the value of its lowest neighbor, and flow is defined toward this cell. If multiple neighbors have the lowest value, the cell is still given this value, but flow is defined with one of the two methods explained below. This is used to filter out one-cell sinks, which are considered noise.
• If a cell has the same change in z-value in multiple directions and that cell is part of a sink, the flow direction is referred to as undefined. In such cases, the value for that cell in the output flow direction raster will be the sum of those directions. For example, if the change in z-value is the same both to the right (flow direction = 1) and down (flow direction = 4), the flow direction for that cell is 1 + 4 = 5. Cells with undefined flow direction can be flagged as sinks using the Sink tool.
• If a cell has the same change in z-value in multiple directions and is not part of a sink, the flow direction is assigned with a lookup table defining the most likely direction. See Greenlee (1987).
• The output drop raster is calculated as the difference in z-value divided by the path length between the cell centers, expressed in percentages. For adjacent cells, this is analogous to the percent slope between cells. Across a flat area, the distance becomes the distance to the nearest cell of lower elevation. The result is a map of percent rise in the path of steepest descent from each cell.When calculating the drop raster in flat areas, the distance to diagonally adjacent cells (1.414 * cell size) is approximated by 1.5 * cell size to increase the processing speed by using integer calculations.
• When using the NORMAL option, a cell at the edge of the surface raster will flow toward the inner cell with the steepest drop in z-value. If the drop is less than or equal to zero, the cell will flow out of the surface raster.

Field Summary

Fields inherited from class com.esri.arcgis.geoprocessing.AbstractGPTool

vals

Constructor Summary

FlowDirection()
Creates the Flow Direction tool with defaults.

FlowDirection(Object inSurfaceRaster, Object outFlowDirectionRaster)
Creates the Flow Direction tool with the required parameters.

Method Summary

String	getForceFlow() Returns the Force all edge cells to flow outward parameter of this tool .
Object	getInSurfaceRaster() Returns the Input surface raster parameter of this tool .
Object	getOutDropRaster() Returns the Output drop raster parameter of this tool .
Object	getOutFlowDirectionRaster() Returns the Output flow direction raster parameter of this tool .
String	getToolboxAlias() Returns the alias of the tool box containing this tool.
String	getToolboxName() Returns the name of the tool box containing this tool.
String	getToolName() Returns the name of this tool.
void	setForceFlow(String forceFlow) Sets the Force all edge cells to flow outward parameter of this tool .
void	setInSurfaceRaster(Object inSurfaceRaster) Sets the Input surface raster parameter of this tool .
void	setOutDropRaster(Object outDropRaster) Sets the Output drop raster parameter of this tool .
void	setOutFlowDirectionRaster(Object outFlowDirectionRaster) Sets the Output flow direction raster parameter of this tool .

Methods inherited from class com.esri.arcgis.geoprocessing.AbstractGPTool

getParameterValues, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

FlowDirection

public FlowDirection()

Creates the Flow Direction tool with defaults.

Initializes the array of tool parameters with the default values specified when the tool was created.

FlowDirection

public FlowDirection(Object inSurfaceRaster,
                     Object outFlowDirectionRaster)

Creates the Flow Direction tool with the required parameters.

Initializes the array of tool parameters with the values as specified for the required parameters and with the default values for the other parameters.

Parameters:

inSurfaceRaster - the input raster representing a continuous surface.

outFlowDirectionRaster - the output raster that shows the flow direction from each cell to its steepest downslope neighbor.

Method Detail

getInSurfaceRaster

public Object getInSurfaceRaster()

Returns the Input surface raster parameter of this tool . This parameter is the input raster representing a continuous surface. This is a required parameter.

Returns:

the Input surface raster

setInSurfaceRaster

public void setInSurfaceRaster(Object inSurfaceRaster)

Sets the Input surface raster parameter of this tool . This parameter is the input raster representing a continuous surface. This is a required parameter.

Parameters:

inSurfaceRaster - the input raster representing a continuous surface.

getOutFlowDirectionRaster

public Object getOutFlowDirectionRaster()

Returns the Output flow direction raster parameter of this tool . This parameter is the output raster that shows the flow direction from each cell to its steepest downslope neighbor. This is a required parameter.

Returns:

the Output flow direction raster

setOutFlowDirectionRaster

public void setOutFlowDirectionRaster(Object outFlowDirectionRaster)

Sets the Output flow direction raster parameter of this tool . This parameter is the output raster that shows the flow direction from each cell to its steepest downslope neighbor. This is a required parameter.

Parameters:

outFlowDirectionRaster - the output raster that shows the flow direction from each cell to its steepest downslope neighbor.

getForceFlow

public String getForceFlow()

Returns the Force all edge cells to flow outward parameter of this tool . This parameter is specifies if edge cells will always flow outward or follow normal flow rules. This is an optional parameter.

Returns:

the Force all edge cells to flow outward

setForceFlow

public void setForceFlow(String forceFlow)

Sets the Force all edge cells to flow outward parameter of this tool . This parameter is specifies if edge cells will always flow outward or follow normal flow rules. This is an optional parameter.

Parameters:

forceFlow - specifies if edge cells will always flow outward or follow normal flow rules.

getOutDropRaster

public Object getOutDropRaster()

Returns the Output drop raster parameter of this tool . This parameter is an optional output drop raster. the drop raster shows the ratio of the maximum change in elevation from each cell along the direction of flow to the path length between centers of cells, expressed in percentages. This is an optional parameter.

Returns:

the Output drop raster

setOutDropRaster

public void setOutDropRaster(Object outDropRaster)

Sets the Output drop raster parameter of this tool . This parameter is an optional output drop raster. the drop raster shows the ratio of the maximum change in elevation from each cell along the direction of flow to the path length between centers of cells, expressed in percentages. This is an optional parameter.

Parameters:

outDropRaster - an optional output drop raster. the drop raster shows the ratio of the maximum change in elevation from each cell along the direction of flow to the path length between centers of cells, expressed in percentages.

getToolName

public String getToolName()

Returns the name of this tool.

Returns:

the tool name

getToolboxName

public String getToolboxName()

Returns the name of the tool box containing this tool.

Returns:

the tool box name

getToolboxAlias

public String getToolboxAlias()

Returns the alias of the tool box containing this tool.

Returns:

the tool box alias