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Thin LAS

Summary

Creates new LAS files which contain a subset of LAS points from the input LAS dataset.

Usage

  • Consider using this tool on over-sampled LAS data, such as photogrammetrically derived point clouds and returns from multiple overlapping lidar scans, to optimize display performance and speed-up analysis operations.

  • Each input LAS file will generate an output. The name of the output file will match the input, unless a name suffix is specified in the Output File Name Suffix parameter.

Syntax

ThinLas_3d (in_las_dataset, target_folder, thinning_dimension, xy_resolution, {z_resolution}, point_selection_method, {class_codes_weights}, {name_suffix}, {out_las_dataset}, {preserved_class_codes}, {preserved_flags}, {preserved_returns}, {excluded_class_codes}, {excluded_flags}, {excluded_returns}, {compression}, {remove_vlr}, {rearrange_points}, {compute_stats})
ParameterExplanationData Type
in_las_dataset

The LAS dataset to process.

LAS Dataset Layer
target_folder

The existing folder that the output LAS files will be written out to.

Folder
thinning_dimension

The type of thinning operation that will be conducted.

  • 2DThinning will occur in tiles defined along the x-y axis.
  • 3DThinning will occur in volumes of space defined by tiles along the x-y axis, and height gradients along the z-axis. This is the default.
String
xy_resolution

The size of each side of the thinning tile along the x-y axis.

Linear Unit
z_resolution
(Optional)

The height of each thinning region when using the 3D thinning method.

Linear Unit
point_selection_method

The method used to determine which points are retained in each thinning region.

  • CLOSEST_TO_CENTERThe LAS point that is closest to the center of the region being thinned. This is the default.
  • CLASS_CODEThe LAS points with the class code that has the highest weight assigned.
  • PREDOMINANT_CLASSThe LAS points with the most frequent class code value in the region being thinned.
  • Z_MINThe lowest LAS point in the region being thinned.
  • Z_MAXThe highest LAS point in the region being thinned.
  • Z_MIN_MAXThe highest and lowest LAS points in the region being thinned.
  • Z_AVERAGEThe LAS point whose height is closest to the average of height of all points in the region being thinned.
  • INTENSITY_MINThe LAS point whose intensity value is the lowest among the points in the region being thinned.
  • INTENSITY_MAXThe LAS point whose intensity value is the highest among the points in the region being thinned.
  • INTENSITY_MIN_MAXThe two LAS points with the lowest and the highest intensity values among the points in the region being thinned.
  • INTENSITY_AVERAGEThe LAS point whose intensity value is closest to the average of all intensity values from points in the region being thinned.
String
class_codes_weights
[class_codes_weights,...]
(Optional)

The weights assigned to each class code that determine which points are retained in each thinning region. This parameter is only enabled when the Class Code Weights option is specified in the Point Selection Method parameter. The class code with the highest weight will be retained in the thinning region. If two class codes with the same weight exist in a given thinning region, both sets of points are retained in the output.

Value Table
name_suffix
(Optional)

The name added to each output file.

String
out_las_dataset
(Optional)

The output LAS dataset referencing the newly created LAS files.

LAS Dataset
preserved_class_codes
[preserved_class_codes,...]
(Optional)

The input LAS points with the specified class code values will be maintained in the output LAS files.

Value Table
preserved_flags
[preserved_flags,...]
(Optional)

The input LAS points with the specified class flag designations will be preserved in the output LAS files.

  • MODEL_KEYPoints with the model key class flag will be preserved.
  • OVERLAPPoints with the overlap class flag will be preserved.
  • SYNTHETICPoints with the synthetic class flag will be preserved.
  • WITHHELDPoints with the withheld class flag will be preserved.
String
preserved_returns
[preserved_returns,...]
(Optional)

The input LAS points with the specified returns will be preserved in the output LAS files.

  • SINGLEAll single return points will be included.
  • LASTAll single and last returns will be included.
  • FIRST_OF_MANYAll points that are the first of multiple returns will be included.
  • LAST_OF_MANYAll points that are the last of multiple returns will be included.
String
excluded_class_codes
[excluded_class_codes,...]
(Optional)

The input LAS points with the specified class code values will be excluded from the output LAS files.

Value Table
excluded_flags
[excluded_flags,...]
(Optional)

The input LAS points with the specified class flag designations will be excluded from the output LAS files.

  • MODEL_KEYPoints with the model key class flag will be excluded.
  • OVERLAPPoints with the overlap class flag will be excluded.
  • SYNTHETICPoints with the synthetic class flag will be excluded.
  • WITHHELDPoints with the withheld class flag will be excluded.
String
excluded_returns
[excluded_returns,...]
(Optional)

The input LAS points with the specified returns will be excluded from the output LAS files.

  • SINGLEAll single return points will be excluded.
  • LASTAll single and last returns will be excluded.
  • FIRST_OF_MANYAll points that are the first of multiple returns will be excluded.
  • LAST_OF_MANYAll points that are the last of multiple returns will be excluded.
String
compression
(Optional)

Specify if the output LAS file will be compressed format or in the standard LAS format.

  • NO_COMPRESSIONThe output will be in the standard LAS format (*.las). This is the default.
  • ZLASOutput LAS files will be compressed in the zLAS format.
String
remove_vlr
(Optional)

Indicates whether variable length records stored with the input LAS points will be preserved or eliminated in the output LAS data.

  • REMOVE_VLRVariable length records will be maintained in the output LAS points. This is the default.
  • MAINTAIN_VLRVariable length records will be removed from the output LAS points.
Boolean
rearrange_points
(Optional)

Determines whether to rearrange points in the LAS files.

  • REARRANGE_POINTSThe order of the points in the LAS files will remain the same.
  • MAINTAIN_POINTSThe points in the LAS files will be rearranged. This is the default.
Boolean
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_STATSStatistics will be computed.
  • NO_COMPUTE_STATSStatistics will not be computed. This is the default.
Boolean

Code sample

ThinLas example 1 (Python window)

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

arcpy.env.workspace = 'C:/data'
arcpy.ddd.ThinLas('photogrammetric_cloud.lasd', 'thinned', '3D', 
                  '20 Centimeters', '15 Centimeters', 'Z_AVERAGE', 
                  excluded_flags='WITHHELD', rearrange_points='REARRANGE_POINTS')

Licensing information

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

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