Analysis Products

Several geographic calculations and analysis are commonly used to answer questions posed during a wildfire incident.

Calculations should only be run on an Offline Copy. Never run any processes or tools on the entire National Incident Feature Service.

Instructions are included for calculating geometry, calculating area by ownership, and calculating line length(s) by type.

Calculate Geometry with Python

It may sometimes be necessary to use a Python expression to calculate feature geometry. Instructions and expression files are provided here.

Calculate Acres on unprojected Feature Classes with Python

These calculations will depend on the spatial reference of the feature class, not the data frame.

  1. Open the layer properties by right-clicking the map in the table of contents and selecting Properties.
  2. Check the layer Spatial Reference to be sure it has the WGS84 Geographic Coordinate System.
    Layer Properties: Event Polygon window. Source and Spatial Reference selected. Geographic coordinates system GCS WGS 1984 highlighted.
  3. Open the Event Polygon attribute table, right-click the Acres field, and select Calculate Field. Alternatively, click Calculate and select Acres as the field name in the Geoprocessing pane.
    Event Polygon attribute table with one row selected. Acres and Calculate Field highlighted.
  4. Enter !shape.geodesicArea​@acres! into the expression field and click Run.
    Geoprocessing pane with GISAcres = !shape.geodesicArea​@acres! entry highlighted.
  5. The Acres field will now be populated.
    Event Polygon attribute table with populated Acres field highlighted.

Calculate Line Lengths on unprojected Feature Classes with Python

These calculations will depend on the spatial reference of the feature class, not the data frame.

  1. Open the layer properties by right-clicking the map in the table of contents and selecting Properties.
  2. Check the layer Spatial Reference to be sure it has the WGS84 Geographic Coordinate System.
    Layer Properties: Event Line window. Source and Spatial Reference selected. Geographic coordinates system GCS WGS 1984 highlighted.
  3. Open the Event Line attribute table, right-click the LengthFeet field, and select Calculate Field. Alternatively, click Calculate and select LengthFeet as the field name in the Geoprocessing pane.
    Event Line attribute table with LengthFeet and Calculate Field highlighted.
  4. Enter !shape.geodesicLength​@feet! into the expression field and click Run.
    Geoprocessing pane with LenthFeet = !shape.geodesicLength​@feet! entry and Run button highlighted.
  5. The LengthFeet field will now be populated.
    Event Line attribute table with populated LengthFeet field highlighted.

Calculate Latitude and Longitude on unprojected Feature Classes with Python

Lat/Long Expression Files (.cal)

These calculations will depend on the spatial reference of the feature class, not the data frame.

  1. Open the layer properties by right clicking the map in the table of contents and selecting Properties.
  2. Check the layer Spatial Reference to be sure it has the WGS84 Geographic Coordinate System.
    Layer Properties: Event Point window. Source and Spatial Reference selected. Geographic coordinates system GCS WGS 1984 highlighted.
  3. Open the Event Point attribute table, right-click the Latitude field, and select Calculate Field. Alternatively, click Calculate and select Latitude as the field name in the Geoprocessing pane.
    Event Point attribute table with Lattitude and Calculate Field highlighted.
  4. In the Calculate Field pane, click the Import button below the Code Block box.
    Calculate Field Pane with Import button highlighted.
  5. Navigate to and select the WGS84_Lat.cal expression file (located in the tools folder).
    Import window open with Project, Folders and WGS84_Lat.cal and OK selected.
  6. This will populate the expression and code block with the necessary script to calculate Latitude in WGS84 DDM. Click Run.
    Geoprocessing pane showing imported Code in Code Block. Run button is highlighted.
  7. Repeat the same steps for the Longitude field but select the WGS84_Long.cal expression file instead.
  8. The Latitude and Longitude fields will now be populated.
    Attribute table showing calculated Latitude and Longitude coordinates.

Calculating Geometry on Projected Feature Classes with Python

An Offline Copy should already be in the local projected coordinate system. It will download in the same coordinate reference system as the data frame of the Edit Project. While this allows the use of non-geodesic (planar) calculations for length and area, the Latitude and Longitude values must still be in WGS84​, requiring a custom calculation. Use of the proper calculation file is critical. For projected data, this is the NotWGS84_ file.

When a feature class Spatial Reference specifies a Projected Coordinate System:

Layer Properties: Event Polygon window. Source and Spatial Reference selected. Projected Coordinate System NAD 1983 UTM Zone 13N highlighted.

  1. To calculate Acres, type !shape.area​@acres! into the expression field and click Run.
  2. To calculate LengthFeet, type !shape.length​@feet! into the expression field and click Run.
    Calculate Field pane with GISAcres = shape.area​@acres! highlighted. Calculate Field pane with LengthFeet = !shape.length​@feet! highlighted.
  3. To calculate Latitude and Longitude in WGS84 Degrees Decimal Minutes requires additional processing of the geometry. Coordinates calculated this way are potentially subject to shifting because of reprojection and transformations are selected automatically.
    • Follow the same instructions for WGS84 features but import the NotWGS84_Lat.cal and NotWGS84_Long.cal files instead.

Calculate Geometry

Acres

  1. From the Event Polygon attribute table, right-click and select Calculate Geometry.
    Event Polygon table with Acres selected and Calculate Geometry highlighted.
  2. The Calculate Geometry window will open.
    Select Area as the Property and Acres as the Area Unit.
    Select Event Polygon as the Coordinate System and it will update to GCS_WGS_1984.
    Calculate Geometry window with Acres and GCS_WGS_1984 populated.
  3. Click OK.
    OK button selected.

Length

  1. From the Event Line attribute table, right-click and select Calculate Geometry.
    Event Line table with LengthFeet selected and Calculate Geometry highlighted.
  2. The Calculate Geometry window will open.
    Select Length as the Property and Feet as the Length Unit.
    Select Event Line as the Coordinate System and it will update to GCS_WGS_1984.
    Calculate Geometry window with Feet (United States) and GCS_WGS_1984 populated.
  3. Click Run.
    Run button selected.

Lat/Long

  1. From the Event Point attribute table, right-click and select Calculate Geometry.
    Event Point table with Latitude WGS84 DDM selected and Calculate Geometry highlighted.
  2. The Calculate Geometry window will open.
    Both Latitude and Longitude can be calculated at once.
    Enter Degrees Decimal Minutes as the format.
    Calculate Geometry window open with Latitude, Longitude and DDM populated.
  3. Click OK.
    OK button selected.

Acreage Burned by Ownership

Prior to calculating the acreage by ownership, a polygon dataset of land ownership will need to be acquired. County level parcel data is often the most accurate; however, national datasets can be used as well. Most common is the “Surface Management Agency” data from the Bureau of Land Management (BLM) (https://navigator.blm.gov/home).

  1. With the ownership data added to the map, open the Geoprocessing pane, search for and open the Clip tool.
    Map with ownership data. Geoprocessing pane open with Clip tool highlighted.
  2. Enter the Ownership data as the Input Features, Event Polygon as the Clip Features, and save it to an appropriate location following GeoOps naming.
    Geoprocessing window with input as ownership, clip features and event polygon and output feature class populated.
  3. Open the resulting feature class’ attribute table and add a field.
    Ownership Clip attribute table with Add Field button highlighted.
  4. Name the field Acres and set the Data Type to Double. Click Save on the Ribbon.
    Fields view with Acres and Double highlighted.
  5. Calculate the Acres field.
    Attribute table with populated Acres column highlighted.

NOTE: If the ownership data has multiple polygons for the same owner, Summary Statistics or Dissolve can be used to combine them.

Line Distance by Feature Category

Calculate the amount of line in the field by type.

  1. After calculating the LengthFeet field, right-click Feature Category and select Summarize.
    Event Line attribute table with Feature Category selected and Summarize highlighted.
  2. The Summary Statistics window will open.
    Enter LengthFeet and Sum as the Field and Statistic Type. Set the output to the Other Incident Data gdb or an appropriate folder and name following GeoOps standards. Click OK.
    Summary Statistics window with Statistics Field, Statistics Type and Case field populated.
  3. The resulting table will return the total length in feet for each feature category present.
    Line Summary table by FC Line Type, Frequency and sum of length in feet.

Percent Containment

The percent containment of a fire is generally the percentage of fire edge that Ops has designated as Contained Line. Always check with the SITL before publishing or printing anything that displays Percent Containment.

There are many methods and custom tools to calculate containment. This example is one of the simplest ways to do so in Pro.

  1. On the Map tab of the ribbon, in the Inquiry section, select Measure Features from the Measure dropdown.
    Map ribbon. Measure selected and Measure Features highlighted.
  2. Set the Distance Units to Feet under the Options and click on the current Wildfire Daily Perimeter.
    Measure Features window showing Area and Perimeter.
  3. If there are multiple polygons, click each and the Sum portion will add them together.
  4. Take the total length of Contained Line from the Line Distance Summary operation described above and divide that by the total Perimeter from the measure tool. Eg. 529 / 1,045 = .506 or 51%.

 

Print This Page

 

Page Last Modified / Reviewed: 
2021-07-21