Set LAS Class Codes Using Features

Summary

Classifies data points in LAS files referenced by a LAS dataset using point, line, and polygon features.

Usage

• The LAS format supports the classification of each point based on the specifications defined by the American Society for Photogrammetry and Remote Sensing (ASPRS). The ArcGIS platform applies the classification scheme specified for LAS file version 1.4:

  Classification Value	Classification Type
  0	Never Classified
  1	Unassigned
  2	Ground
  3	Low Vegetation
  4	Medium Vegetation
  5	High Vegetation
  6	Building
  7	Low Noise
  8	Model Key / Reserved
  9	Water
  10	Rail
  11	Road Surface
  12	Overlap / Reserved
  13	Wire – Guard
  14	Wire – Conductor
  15	Transmission Tower
  16	Wire – Connector
  17	Bridge Deck
  18	High Noise
  19 – 63	Reserved for ASPRS Definition (LAS 1.1 to 1.3 support up to class code 31)
  32 – 255	User Definable (Only supported in LAS 1.0 and certain versions of 1.4)

  Note:

  While the bulk of new class code assignments introduced with LAS 1.4 were previously designated as Reserved, class codes 8 and 12 were changed from Model Key and Overlap to Reserved.

• The LAS dataset layer can also be used to control the enforcement of surface constraint features that may be referenced by the LAS dataset.

• LAS data points that fall within the 2-dimensional area of the buffer specified for the input features will be classified.

• Consider using the points obtained from Locate Outliersto classify LAS points as Noise.

Syntax

SetLasClassCodesUsingFeatures_3d (in_las_dataset, feature_class, {compute_stats})

Parameter	Explanation	Data Type
in_las_dataset	The LAS dataset to process.	LAS Dataset Layer
feature_class [[features, buffer_distance, new_class, synthetic, key_point, withheld],...]	Specify one or more feature classes that will be used to define class code values for the lidar files referenced by a LAS dataset. Each feature will have the following options that can be specified: features—The feature layer or full path to the input feature class. buffer_distance—The selection tolerance used in determining which lidar points will be modified by the input features. new_class—The class code to be assigned to the lidar files that intersect with the features and the associated buffer distance. synthetic—Specifies whether to flag or remove a Synthetic designation, which implies that the point was not created with lidar, but an alternate technique (for example, digitized from photogrammetric stereo model). key_point—Specifies whether to flag or remove a Key Point designation for the data point. A model key point is typically treated as an anchor point that does not get removed by any thinning algorithm. withheld—Specifies whether to flag or remove a Withheld designation for the data point, which is generally used to signify erroneous data.	Value Table
compute_stats (Optional)	Specifies whether statistics should be computed for the LAS files referenced by the LAS dataset. The presence of statistics allows the LAS dataset layer's filtering and symbology options to only show LAS attribute values that exist in the LAS files. COMPUTE_STATS —Statistics will be computed. NO_COMPUTE_STATS —Statistics will not be computed. This is the default.	Boolean

Code Sample

SetLasClassCodesUsingFeatures 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.SetLasClassCodesUsingFeatures_3d("test.lasd", [["lake.shp 0 9"],
                                       ["outliers.shp", 5, "NO_CHANGE", 
                                        "NO_CHANGE", "NO_CHANGE", "SET"]], 
                                       "COMPUTE_STATS")

SetLasClassCodesUsingFeatures example 2 (stand-alone script)

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

'''**********************************************************************
Name: Assign Withheld Classification Flag to Outlier Points in LAS Files
Description: Uses Locate Outliers to identify points in LAS files that
             should be assigned the 'withheld' classification flag.
             Designed for use as a script tool.
**********************************************************************'''
# Import system modules
import arcpy
import exceptions, sys, traceback

try:
    arcpy.CheckOutExtension('3D')
    # Set Local Variables
    lasD = arcpy.GetParameterAsText(0)
    outliers = 'in_memory/outliers'
    # Execute LocateOutliers
    arcpy.ddd.LocateOutliers(lasD, outliers, 'APPLY_HARD_LIMIT', -10, 
                             350, 'APPLY_COMPARISON_FILTER', 1.2, 120, 
                             0.8, 8000)
    # Execute SetLasClassCodeUsingFeatures
    arcpy.ddd.SetLasClassCodesUsingFeatures(lasd, [["outliers.shp", 5, 
                                                    "NO_CHANGE", "NO_CHANGE",
                                                    "NO_CHANGE", "SET"]])
    arcpy.CheckInExtension('3D')
except arcpy.ExecuteError:
    print arcpy.GetMessages()
except:
    # Get the traceback object
    tb = sys.exc_info()[2]
    tbinfo = traceback.format_tb(tb)[0]
    # Concatenate error information into message string
    pymsg = 'PYTHON ERRORS:\nTraceback info:\n{0}\nError Info:\n{1}'\
          .format(tbinfo, str(sys.exc_info()[1]))
    msgs = 'ArcPy ERRORS:\n {0}\n'.format(arcpy.GetMessages(2))
    # Return python error messages for script tool or Python Window
    arcpy.AddError(pymsg)
    arcpy.AddError(msgs)

Environments

• Current Workspace
• Extent
• Geographic Transformations

Licensing Information

• ArcGIS for Desktop Basic: Requires 3D Analyst
• ArcGIS for Desktop Standard: Requires 3D Analyst
• ArcGIS for Desktop Advanced: Requires 3D Analyst

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