Raster To Multipoint (3D Analyst)

Summary

Converts raster cell centers into multipoint features whose Z values reflect the raster cell value.

Usage

• This tool is intended for raster datasets that model surface properties, such as elevation.

• This tool is useful for incorporating a raster DEM into points that can be used as ancillary data for creating a Terrain dataset or TIN.

• All the cell centers can be converted, using the NO_THIN option, or one of several filters can be applied to exclude those cells that are less significant. The thinning options include ZTOLERANCE, KERNEL, and VIP.

  • The ZTOLERANCE thinning method represents the maximum allowable difference (in z-units) between the height of the input raster and the height of the output multipoint feature class. By default, the Z tolerance is 1/10 of the z-range of the input raster. The larger the tolerance, the more thinning, and the fewer points output.
  • The KERNEL thinning method defines the number of cells for a window. The default is 3, which translates into a 3 by 3 set of cells in the input raster. The individual cell values in each of these windows are evaluated. Then just one or two cells are chosen, depending on the KERNEL selection method. The larger the kernel size, the more thinning will be carried out, and the fewer points output.
  • The VIP method is used to select a percentage of points from the input raster based on their significance. The significance is assessed using a roving 3 by 3 window. You can chose the VIP_HISTOGRAM option to write out a table to view the actual significance values and the corresponding number of points associated with those values.

• Use the ZTOLERANCE thinning method when it is important to preserve vertical accuracy. Use the KERNEL thinning method when it is important to control the horizontal sample distance.

• Consider applying a thinning method when converting from raster to multipoints. There are two thinning methods used to generate a new multipoint feature class: ZTOLERANCE and KERNEL. If NO_THIN is selected, the full resolution data will be output into a new multipoint feature class.

• The VIP method is relatively fast, outputs a predictable number of points, and is good at selecting local peaks and pits. However, it is sensitive to noise and insensitive to topographic features that are larger than the 3 by 3 window.

Syntax

RasterToMultipoint_3d (in_raster, out_feature_class, {out_vip_table}, {method}, {kernel_method}, {z_factor})

Parameter	Explanation	Data Type
in_raster	The input raster.	Raster Layer
out_feature_class	The output feature class.	Feature Class
out_vip_table (Optional)	The histogram table to be produced when VIP Histogram is specified for the Method parameter.	Table
method (Optional)	The thinning method applied to generate the multipoint feature class. NO_THIN —The full resolution data will be output into a new multipoint feature class. ZTOLERANCE —The maximum allowable difference in (z units) between the height of the input raster and the height of the output multipoint feature class. By default, the z tolerance is 1/10 of the z range of the input raster. The larger the tolerance, the more thinning, the fewer points output. KERNEL —Defines the number of cells for a window. The default is 3, which translates into a 3 by 3 set of cells in the input raster. The individual cell values in each of these windows are evaluated. Then just one or two cells are chosen, depending on the KERNEL selection method. The larger the kernel size, the more thinning will be carried out, and the fewer points output. VIP —Selects a percentage of points from the input raster based on their significance. The significance is assessed using a roving 3 by 3 window. VIP_HISTOGRAM —Creates a table to view the actual significance values and the corresponding number of points associated with those values.	String
kernel_method (Optional)	The selection method used for creating points when kernel thinning is specified in the Method parameter. MIN —A point is created at the cell with the smallest elevation value found in the kernel neighborhood. This is the default. MAX —A point is created at the cell with the largest elevation value found in the kernel neighborhood. MINMAX —Two points are created at the cells with the smallest and largest elevation values found in the kernel neighborhood. MEAN —A point is created at the cell whose elevation value is closest to the average of the cells in the kernel neighborhood.	String
z_factor (Optional)	The factor used for multiplying the elevation of the raster. Generally used to convert units between feet and meters.	Double

Code Sample

RasterToMultipoint example 1 (Python window)

The following sample demonstrates the use of this tool in the Python window:

import arcpy
from arcpy import env

arcpy.CheckOutExtension("3D")
env.workspace = "C:/data"
arcpy.RasterToMultipoint_3d("elevation.tif", "","elev_VIP.dbf", "VIP_HISTOGRAM", "", "1")

RasterToMultipoint example 2 (stand-alone script)

The following sample demonstrates the use of this tool in a stand-alone Python script:

'''*********************************************************************
Name: RasterToMultipoint Example
Description: This script demonstrates how to use
             the RasterToMultipoint tool to create multipoint datasets
             fot all IMG rasters in a target workspace.
**********************************************************************'''
# Import system modules
import arcpy
from arcpy import env
import exceptions

try:
    arcpy.CheckOutExtension("3D")
    # Set default workspace
    env.workspace = "C:/data"
    # Create the list of IMG rasters
    rasterList = arcpy.ListRasters("*", "IMG")
    # Loop the process for each raster
    if rasterList:
        for raster in rasterList:
            # Set Local Variables
            # [:-4] strips the last 4 characters (.img) from the raster name
            outTbl = "VIP_" + raster[:-4] + ".dbf"
            method = "VIP_HISTOGRAM"
            zfactor = 1
            #Execute RasterToMultipoint
            arcpy.ddd.RasterToMultipoint(raster, "",outTbl, method, "", zfactor)
    else:
        "There are no IMG rasters in the " + env.workspace + " directory."
except Exception as e:
    # Returns any other error messages
    print e.message

Environments

Current Workspace, Scratch Workspace, Output Coordinate System, Extent, Geographic Transformations, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance, Output XY Domain, Output Z Domain, Output CONFIG Keyword, Auto Commit, Output Spatial Grid 1, 2, 3

Licensing Information

ArcView: Requires 3D Analyst

ArcEditor: Requires 3D Analyst

ArcInfo: Requires 3D Analyst