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Create LAS Dataset

Summary

Creates a LAS dataset referencing one or more LAS files and optional surface constraint features.

Illustration

Create LAS Dataset

Usage

  • The LAS dataset is designed for use with lidar data in the .las or .zlas formats. LAS file versions 1.0 - 1.4 are supported. Esri's EzLAS Optimizer is a stand-alone lidar utility that can be used to generate .zlas files or convert them back to the .las format.

  • Each LAS file is examined to determine if its internal structure is consistent with the LAS specifications. If any LAS file fails to load into the LAS dataset, this may indicate the file is corrupted or has erroneous information in its header. Consider using Esri's CheckLAS utility to determine if some commonly encountered issues may exist in your data.

  • Surface constraint features can be used to enforce feature-derived elevation values that represent surface characteristics in the LAS dataset.

  • Each LAS file typically contains spatial reference information in its header which is read by the LAS dataset. If this information is missing or improperly defined, the LAS file will not be placed in its correct location. If the correct spatial reference is known, consider using the Create PRJ For LAS parameter to create a .prj file that properly georeferences the lidar data. The .prj file will share the LAS file's name, reside in the same folder, and contain the well-known text representation of the LAS file's coordinate system, similar to the .prj file associated with a shapefile.

  • 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.

  • In the tool dialog window, a folder can also be specified as an input by selecting the desired folder in Windows Explorer and dragging it into the parameter's input box.

Syntax

CreateLasDataset_management (input, out_las_dataset, {folder_recursion}, {in_surface_constraints}, {spatial_reference}, {compute_stats}, {relative_paths}, create_las_prj)
ParameterExplanationData Type
input
[input,...]

The LAS files and folders containing LAS files that will be referenced by the LAS dataset. This information can be supplied as a string containing all the input data or a list of strings containing specific data elements (for example, "lidar1.las; lidar2.las; folder1; folder2" or ["lidar1.las", "lidar2.las", "folder1", "folder2"]).

File; Folder
out_las_dataset

The LAS dataset that will be created.

LAS Dataset
folder_recursion
(Optional)

Specifies whether lidar data residing in the subdirectories of an input folder will be added to the LAS dataset.

  • NO_RECURSIONOnly lidar files found in an input folder will be added to the LAS dataset. This is the default.
  • RECURSIONAll LAS files residing in the subdirectories of an input folder will be added to the LAS dataset.
Boolean
in_surface_constraints
[[in_feature_class, height_field, SF_type],...]
(Optional)

The features that will be referenced by the LAS dataset when generating a triangulated surface. Each feature will need the following properties defined:

in_feature_class—The feature to be referenced by the LAS dataset.

height_field—Any numeric field in the feature's attribute table can be used to define the height source. If the feature's geometry contains z-values, it can be selected by specifying Shape.Z. If no height is desired, specify the keyword <None> to create Z-less features whose elevation would be interpolated from the surface.

SF_type—The surface feature type that defines how the feature geometry gets incorporated into the triangulation for the surface. Options with hard or soft designation refer to whether the feature edges represent distinct breaks in slope or a gradual change.

  • anchorpoints—Elevation points that never get thinned away. This option is only available for single-point feature geometry.
  • hardline or softline—Breaklines that enforce a height value.
  • hardclip or softclip—Polygon dataset that defines the boundary of the LAS dataset.
  • harderase or softerase—Polygon dataset that defines holes in the LAS dataset.
  • hardreplace or softreplace—Polygon dataset that defines areas of constant height.
Value Table
spatial_reference
(Optional)

The spatial reference of the LAS dataset. If no spatial reference is explicitly assigned, the LAS dataset will use the coordinate system of the first input LAS file. If the input files do not contain any spatial reference information and the Input Coordinate System is not set, then the LAS dataset's coordinate system will be listed as unknown.

Coordinate System
compute_stats
(Optional)

Specifies whether statistics for the LAS files will be computed and a spatial index generated for 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. A .lasx auxiliary file is created for each LAS file.

  • COMPUTE_STATSStatistics will be computed.
  • NO_COMPUTE_STATSStatistics will not be computed. This is the default.
Boolean
relative_paths
(Optional)

Specifies whether lidar files and surface constraint features will be referenced by the LAS dataset through relative or absolute paths. Using relative paths may be convenient for cases where the LAS dataset and its associated data will be relocated in the file system using the same relative location to one another.

  • ABSOLUTE_PATHSAbsolute paths will be used for the data referenced by the LAS dataset. This is the default.
  • RELATIVE_PATHSRelative paths will be used for the data referenced by the LAS dataset.
Boolean
create_las_prj

Specifies whether .prj files will be created for the LAS files referenced by the LAS dataset.

  • NO_FILESNo files will have a PRJ file created. This is the default.
  • FILES_MISSING_PROJECTIONOnly LAS files without a spatial reference will have a corresponding PRJ file.
  • ALL_FILESAll LAS files will have a corresponding PRJ file.
String

Code sample

CreateLasDataset example 1 (Python window)

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

import arcpy
from arcpy import env

env.workspace = "C:/data"
arcpy.CreateLasDataset_management("folder_a; folder_b/5S4E.las", 
                                "test.lasd", "RECURSION",
                                "LA/boundary.shp <None> Softclip;"\
                                "LA/ridges.shp Elevation hardline", "", 
                                "COMPUTE_STATS", "RELATIVE_PATHS")
CreateLasDataset example 2 (stand-alone script)

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

'''*********************************************************************
Name: Export Elevation Raster from Ground LAS Measurements
Description: This script demonstrates how to export
             ground measurements from LAS files to a raster using a
             LAS dataset. This sample is designed to be used as a script
             tool.
*********************************************************************'''
# Import system modules
import arcpy

try:
    # Set Local Variables
    inLas = arcpy.GetParameterAsText(0)
    recursion = arcpy.GetParameterAsText(1)
    surfCons = arcpy.GetParameterAsText(2)
    classCode = arcpy.GetParameterAsText(3)
    returnValue = arcpy.GetParameterAsText(4)
    spatialRef = arcpy.GetParameterAsText(5)
    lasD = arcpy.GetParameterAsText(6)
    outRaster = arcpy.GetParameterAsText(7)
    cellSize = arcpy.GetParameter(8)
    zFactor = arcpy.GetParameter(9)

    # Execute CreateLasDataset
    arcpy.management.CreateLasDataset(inLas, lasD, recursion, surfCons, sr)
    # Execute MakeLasDatasetLayer
    lasLyr = arcpy.CreateUniqueName('Baltimore')
    arcpy.management.MakeLasDatasetLayer(lasD, lasLyr, classCode, returnValue)
    # Execute LasDatasetToRaster
    arcpy.conversion.LasDatasetToRaster(lasLyr, outRaster, 'ELEVATION',
                              'TRIANGULATION LINEAR WINDOW_SIZE 10', 'FLOAT',
                              'CELLSIZE', cellSize, zFactor)
    print(arcpy.GetMessages())

except arcpy.ExecuteError:
    print(arcpy.GetMessages())

except Exception as err:
    print(err.args[0])

finally:
    arcpy.management.Delete(lasLyr)

Licensing information

  • ArcGIS Desktop Basic: Requires 3D Analyst or Spatial Analyst
  • ArcGIS Desktop Standard: Yes
  • ArcGIS Desktop Advanced: Yes

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