Tool Intersection Density
Estimates the intersection density of roads within a given search radius for any pixel in the output raster. Intersections are defined as any point where three or more roads meet and density is calculated using kernel density, where closer intersections are weighted higher than further intersections.
The kernel density operation uses the Planar option for calculations. For accurate results, the analysis should to be performed at a local scale with a projection that accurately maintains the correct distance and area.
To be edited.
ID (Road_feature, {Merge_divided_roads}, {Merge_field}, Merge_distance, Output_Coordinate_System, Density_raster_cell_size, Density_raster_search_radius, Density_raster_area_units, Output_raster, {Select_options})
| Parameter | Explanation | Data Type |
|---|---|---|
| Road_feature | The vector line dataset representing roads or other linear features to be measured. | Feature Layer |
| Merge_divided_roads (Optional) | Specifies whether to merge matched pairs of divided roads into single-line road features before calculating intersection points. Matched pairs of roads are merged if they are the same road class, trend generally parallel to one another, and are within the merge distance apart.
|
Boolean |
| Merge_field (Optional) | The field that contains road classification information. Only parallel, proximate roads of equal classification will be merged. A value of 0 (zero) locks a feature to prevent it from participating in merging. This parameter may be left blank. If blank, all parallel roads within the specified distance will be merged. |
|
| Merge_distance | The minimum distance apart, in the specified units, for equal-class, relatively parallel road features to be merged. This distance must be greater than zero. | Linear Unit |
| Output_Coordinate_System | The coordinate system used for the output data. Its linear units are used to define the distance units in Merge distance, Density raster cell size, and Density raster search radius parameters. |
Coordinate System |
| Density_raster_cell_size | The cell size of the output raster that will be created. Units use the linear unit of the Output Coordinate System. |
Double |
| Density_raster_search_radius | The search radius within which to calculate density. Units are based on the linear unit of the projection of the output spatial reference. For example, if the units are meters—to include all features within a one-mile neighborhood—set the search radius equal to 1609.344 (1 mile = 1609.344 meters). The default search radius is computed specifically for the input dataset using a spatial variant of Silverman's Rule of Thumb (Silverman, 1986) that is robust enough for spatial outliers (points that are far away from the rest of the points). See the usage tips for a description of the algorithm. |
Double |
| Density_raster_area_units | The area units of the output density values. | String |
| Output_raster | The output intersection density raster. It is always a floating point raster. |
Raster Dataset |
| Select_options (Optional) | One tool option is available to provide additional information:
|
Multiple Value |
-
id_[Road_feature]_Prj_# -
-
id_[Road_feature]_SglPrt_# -
-
id_[Road_feature]_Merged_# -
-
id_[Road_feature]_UnSplit_# -
-
id_[Road_feature]_Intersections_# -
Intersection Density example 1 (Python window)
This example returns a raster with an estimate of the number of road intersections per square kilometer for every cell in the output raster. The option to merge roads of the same class in close proximity to each other was not selected. The option to retain the intermediate calculation products was selected.
import arcpy
arcpy.ImportToolbox(r"D:\Destination Folder\ATtILA v2.tbx")
Road_feature = r"D:\pyexamples\data.gdb\Roads"
Merge_divided_roads = False
Merge_field = None
Merge_distance = None
Output_Coordinate_System = 'PROJCS["Albers_Conical_Equal_Area",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Albers"],PARAMETER["false_easting",0.0],PARAMETER["false_northing",0.0],PARAMETER["central_meridian",-96.0],PARAMETER["standard_parallel_1",29.5],PARAMETER["standard_parallel_2",45.5],PARAMETER["latitude_of_origin",23.0],UNIT["Meter",1.0]]'
Density_raster_cell_size = 10
Density_raster_search_radius = 750
Density_raster_area_units = "SQUARE KILOMETERS"
Output_raster = r"D:\pyexamples\results.gdb\Road_Intersection_Hotspots2"
Select_options = "'INTERMEDIATES - Retain Intermediate Layers Generated During Metric Calculation'"
arcpy.ATtILA.ID(Road_feature,
Merge_divided_roads,
Merge_field,
Merge_distance,
Output_Coordinate_System,
Density_raster_cell_size,
Density_raster_search_radius,
Density_raster_area_units,
Output_raster,
Select_options)Intersection Density example 2 (Tool Details Messages)
This is a sample capture of the geoprocessing messages generated during a typical tool run. It is provided here to assist in the understanding of the tool's processing steps.
Start Time: Day, Month dd, yyyy hh:mm:ss AM/PM
Started: yyyy-mm-dd hh:mm:ss Setting up environment variables
Using Roads's extent for geoprocessing steps.
Time: yyyy-mm-dd hh:mm:ss Projecting Roads to Albers_Conical_Equal_Area. Intermediate: id_Roads_Prj_0
Time: yyyy-mm-dd hh:mm:ss Converting Multipart features to Singlepart. Intermediary output: id_Roads_SglPrt_0
Time: yyyy-mm-dd hh:mm:ss Merging divided road features. Intermediary output: id_Roads_Merged_0
Time: yyyy-mm-dd hh:mm:ss Unsplitting id_Roads_Merged_0. Intermediate: id_Roads_UnSplit_0
Time: yyyy-mm-dd hh:mm:ss Finding intersections. Intermediate: id_Roads_Intersections_0.
Time: yyyy-mm-dd hh:mm:ss Deleting identical intersections...
Time: yyyy-mm-dd hh:mm:ss Performing kernel density: Result saved as Road_Intersection_Hotspots2.
Adding output raster to Map view
Cleaning up intermediate datasets
Succeeded at Day, Month dd, yyyy hh:mm:ss AM/PM (Elapsed Time: ##.## units)
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