Classify LAS Building (3D Analyst)

Summary

Classifies buildings in LAS format point cloud data.

Illustration

Usage

• Points with class code values of 0, 1, and 6 will be evaluated to determine if they fit the characteristics of building rooftops. Existing building classified points that do not satisfy the detection criteria will be reassigned to 1 unless the option to reuse existing building classified points has been set.

• This tool was designed with an emphasis on aerial lidar, which usually captures building rooftops. Points representing walls, vertical facades, and small rooftop features—such as dormers and chimneys—may not be included in the building classification. If such points are necessary, consider running the tool with the options for classifying points that are above and below the roof.

• Classify ground points before running this tool. If ground points have not been classified, use the Classify LAS Ground tool. If ground points are classified but they use a class code value other than 2, use the Change LAS Class Codes tool to reassign them accordingly.

• The Method parameter is not used when the Is photogrammetric data parameter is checked.

Parameters

Dialog

Label	Explanation	Data Type
Input LAS Dataset	The LAS dataset that will be classified.	LAS Dataset Layer
Minimum Rooftop Height (Optional)	The height from the ground that defines the lowest point from which rooftop points will be identified.	Linear Unit
Minimum Area	The smallest area of the building rooftop.	Areal Unit
Compute statistics (Optional)	Specifies whether statistics will be computed for the .las files referenced by the LAS dataset. Computing statistics provides a spatial index for each .las file, which improves analysis and display performance. Statistics also enhance the filtering and symbology experience by limiting the display of LAS attributes, such as classification codes and return information, to values that are present in the .las file. Checked—Statistics will be computed. This is the default. Unchecked—Statistics will not be computed.	Boolean
Processing Extent (Optional)	The extent of the data that will be evaluated. Current Display Extent —The extent will be based on the active map or scene. Draw Extent —The extent will be based on a rectangle drawn on the map or scene. Extent of a Layer —The extent will be based on an active map layer. Choose an available layer or use the Extent of data in all layers option. Each map layer has the following options: All Features —The extent of all features. Selected Features —The extent of the selected features. Visible Features —The extent of visible features. Browse —The extent will be based on a dataset. Intersection of Inputs —The extent will be the intersecting extent of all inputs. Union of Inputs —The extent will be the combined extent of all inputs. Clipboard —The extent can be copied to and from the clipboard. Copy Extent —Copies the extent and coordinate system to the clipboard. Paste Extent —Pastes the extent and coordinate system from the clipboard. If the clipboard does not include a coordinate system, the extent will use the map’s coordinate system. Reset Extent —The extent will be reset to the default value. When coordinates are manually provided, the coordinates must be numeric values and in the active map's coordinate system. The map may use different display units than the provided coordinates. Use a negative value sign for south and west coordinates.	Extent
Processing Boundary	The polygon feature or features that will define the area to be processed.	Feature Layer
Process entire LAS files that intersect extent (Optional)	Specifies how the area of interest will be used in determining how .las files will be processed. The area of interest is defined by the Processing Extent parameter value, the Processing Boundary parameter value, or a combination of both. Unchecked—Only LAS points that intersect the area of interest will be processed. This is the default. Checked—If any portion of a .las file intersects the area of interest, all the points in that file, including those outside the area of interest, will be processed.	Boolean
Average Point Spacing	The average spacing of LAS points. This parameter is no longer used.	Linear Unit
Reuse existing building classified points (Optional)	Specifies whether the existing building classified points will be reused or reevaluated. Unchecked—Existing building classified points will be reevaluated to fit the criteria for plane detection, and points that do not fit the specified area and height will be assigned a value of 1. This is the default. Checked—Existing building classified points will contribute to the plane detection process but will not be reclassified in the event they do not meet the criteria specified by the tool. Use this option if the existing classification is necessary.	Boolean
Is photogrammetric data (Optional)	Specifies whether the points in the .las file were derived using a photogrammetric technique. Unchecked—The points in the .las file were obtained from a lidar survey, not from a photogrammetric technique for producing point clouds. This is the default. Checked—The points in the .las file were obtained using a photogrammetric technique for producing point clouds from overlapping imagery.	Boolean
Classification Method (Optional)	Specifies the classification method that will be used. Aggressive—Points that fit the planar rooftop characteristics with a relatively high tolerance for outliers will be detected. Use this method if the points are not well calibrated. Standard—Points that fit the planar rooftop characteristics with a relatively moderate tolerance for irregular points will be detected. This is the default Conservative—Points that fit the planar rooftop characteristics with a relatively low tolerance for irregular points will be detected. Use this method if the building points are co-planar with points from objects that are not buildings.	String
Classify points above the roof (Optional)	Specifies whether points above the planes detected for the roof will be classified. Unchecked—Points detected above the planes will not be classified. This is the default. Checked—Points detected above the planes will be classified.	Boolean
Maximum Height Above Roof (Optional)	The maximum height of the points above the building rooftop that will be classified using the Above Roof Class Code parameter value.	Linear Unit
Above Roof Class Code (Optional)	The class code that will be assigned to points above the roof.	Long
Classify points below the roof (Optional)	Specifies whether points between the roof and the ground will be classified. Unchecked—Points between the roof and the ground will not be classified. This is the default. Checked—Points between the roof and the ground will be classified.	Boolean
Below Roof Class Code (Optional)	The class code that will be assigned to points between the ground and the roof.	Long
Update pyramid (Optional)	Specifies whether the LAS dataset pyramid will be updated after the class codes are modified. Checked—The LAS dataset pyramid will be updated. This is the default. Unchecked—The LAS dataset pyramid will not be updated.	Boolean

Derived Output

Label	Explanation	Data Type
Derived LAS Dataset	The LAS dataset that is classified for building rooftops.	LAS Dataset Layer

Python

arcpy.ddd.ClassifyLasBuilding(in_las_dataset, {min_height}, min_area, {compute_stats}, {extent}, boundary, {process_entire_files}, point_spacing, {reuse_building}, {photogrammetric_data}, {method}, {classify_above_roof}, {above_roof_height}, {above_roof_code}, {classify_below_roof}, {below_roof_code}, {update_pyramid})

Name	Explanation	Data Type
in_las_dataset	The LAS dataset that will be classified.	LAS Dataset Layer
min_height (Optional)	The height from the ground that defines the lowest point from which rooftop points will be identified.	Linear Unit
min_area	The smallest area of the building rooftop.	Areal Unit
compute_stats (Optional)	Specifies whether statistics will be computed for the .las files referenced by the LAS dataset. Computing statistics provides a spatial index for each .las file, which improves analysis and display performance. Statistics also enhance the filtering and symbology experience by limiting the display of LAS attributes, such as classification codes and return information, to values that are present in the .las file. COMPUTE_STATS—Statistics will be computed. This is the default. NO_COMPUTE_STATS—Statistics will not be computed.	Boolean
extent (Optional)	The extent of the data that will be evaluated. MAXOF—The maximum extent of all inputs will be used. MINOF—The minimum area common to all inputs will be used. DISPLAY—The extent is equal to the visible display. Layer name—The extent of the specified layer will be used. Extent object—The extent of the specified object will be used. Space delimited string of coordinates—The extent of the specified string will be used. Coordinates are expressed in the order of x-min, y-min, x-max, y-max.	Extent
boundary	The polygon feature or features that will define the area to be processed.	Feature Layer
process_entire_files (Optional)	Specifies how the processing extent will be applied. PROCESS_EXTENT—Only LAS points that intersect the area of interest will be processed. This is the default. PROCESS_ENTIRE_FILES—If any portion of a .las file intersects the area of interest, all the points in that file, including those outside the area of interest, will be processed.	Boolean
point_spacing	The average spacing of LAS points. This parameter is no longer used.	Linear Unit
reuse_building (Optional)	Specifies whether the existing building classified points will be reused or reevaluated. Specifies whether the existing building classified points will be reused or reevaluated. RECLASSIFY_BUILDING—Existing building classified points will be reevaluated to fit the criteria for plane detection, and points that do not fit the specified area and height will be assigned a value of 1. This is the default. REUSE_BUILDING—Existing building classified points will contribute to the plane detection process but will not be reclassified in the event they do not meet the criteria specified by the tool. Use this option if the existing classification is necessary.	Boolean
photogrammetric_data (Optional)	Specifies whether the points in the .las file were derived using a photogrammetric technique. Specifies whether the points in the .las file were derived using a photogrammetric technique. NOT_PHOTOGRAMMETRIC_DATA—The points in the .las file were obtained from a lidar survey, not from a photogrammetric technique for producing point clouds. This is the default. PHOTOGRAMMETRIC_DATA—The points in the .las file were obtained using a photogrammetric technique for producing point clouds from overlapping imagery.	Boolean
method (Optional)	Specifies the classification method that will be used. AGGRESSIVE—Points that fit the planar rooftop characteristics with a relatively high tolerance for outliers will be detected. Use this method if the points are not well calibrated. STANDARD—Points that fit the planar rooftop characteristics with a relatively moderate tolerance for irregular points will be detected. This is the default CONSERVATIVE—Points that fit the planar rooftop characteristics with a relatively low tolerance for irregular points will be detected. Use this method if the building points are co-planar with points from objects that are not buildings.	String
classify_above_roof (Optional)	Specifies whether points above the planes detected for the roof will be classified. NO_CLASSIFY_ABOVE_ROOF—Points detected above the planes will not be classified. This is the default.. CLASSIFY_ABOVE_ROOF—Points detected above the planes will be classified.	Boolean
above_roof_height (Optional)	The maximum height of the points above the building rooftop that will be classified using the above_roof_code parameter value.	Linear Unit
above_roof_code (Optional)	The class code that will be assigned to points above the roof.	Long
classify_below_roof (Optional)	Specifies whether points between the roof and the ground will be classified. NO_CLASSIFY_BELOW_ROOF—Points between the roof and the ground will not be classified. This is the default. CLASSIFY_BELOW_ROOF—Points between the roof and the ground will be classified.	Boolean
below_roof_code (Optional)	The class code that will be assigned to points between the ground and the roof.	Long
update_pyramid (Optional)	Specifies whether the LAS dataset pyramid will be updated after the class codes are modified. UPDATE_PYRAMID—The LAS dataset pyramid will be updated. This is the default. NO_UPDATE_PYRAMID—The LAS dataset pyramid will not be updated.	Boolean

Derived Output

Name	Explanation	Data Type
derived_las_dataset	The LAS dataset that is classified for building rooftops.	LAS Dataset Layer

Code sample

ClassifyLasBuilding example 1 (Python window)

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

arcpy.env.workspace = 'C:/data'

arcpy.ddd.ClassifyLasBuilding('Highland.lasd', minHeight='9 feet', 
                              minArea='30 Square Feet', compute_stats=True)

ClassifyLasBuilding example 2 (stand-alone script)

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

'''****************************************************************************
       Name: Tile & Classify LAS Files
Description: Creates & classifies tiled LAS files.
****************************************************************************'''
# Import system modules
import arcpy
import tempfile
import math

in_las = arcpy.GetParameterAsText(1) # The LAS files that need to be tiled
out_folder = arcpy.GetParameterAsText(2) # folder for LAS files
basename = arcpy.GetParameterAsText(3) # basename for output files
out_lasd = arcpy.GetParameterAsText(4) # output LAS dataset


try:
    # Create temp LAS dataset to reference LAS files that will be tiled
    temp_lasd = arcpy.CreateUniqueName('temp.lasd', tempfile.gettempdir())
    arcpy.management.CreateLasDataset(in_las, temp_lasd)
    arcpy.ddd.TileLas(temp_lasd, out_folder, basename, out_lasd, las_version=1.4, 
                      point_format=7, file_size=300)
    arcpy.management.Delete(temp_lasd)
    arcpy.ddd.ClassifyLasGround(out_lasd, method='AGGRESSIVE')
    arcpy.ddd.ClassifyLasBuilding(out_lasd, min_height='3 Meters', min_area='4 Meters')
    arcpy.ddd.ClassifyLasByHeight(out_lasd, height_classification=[(3, 6), (4,20), (5,70)],
                                  noise='All Noise', compute_stats='COMPUTE_STATS')

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

Environments

Extent, Parallel Processing Factor