This model combines the first three pre-processing steps in the raster dasymetric mapping routine. First, it converts a polygon feature class to an integer raster using the ObjectID of the feature class for the value of the output raster. Next, it combines the population raster and an ancillary raster and creates a standalone table for dasymetric calculations. Last, it creates a standalone table that can contain preset density values for all the unique classes in the ancillary dataset. After the table is created, it will need to be manually populated with preset density values, and classes that should not be preset should be removed from the table.

Usage Tips

We tried allowing the user to designate a field that would become the raster cell values, but found that ArcGIS handled this field differently depending on the formats of the input file and the output raster. Always using the field ArcGIS recognizes as the ObjectID field eliminated this inconsistency. A user may specify their own population key field, and this field will be included in the output population raster and population working table, but it will be included only for the convenience of the user, not for any functional part of the script.

In this script the ancillary raster is used only to determine the spatial reference and cell size of the output population raster so that the two rasters are aligned when they are combined in the next script. In most cases the ancillary raster is a land-use or land-cover dataset. The cell assignment type is likely only relevant if the cell size is large relative to the population areal units, and any choice other than the default (Cell_Center) significantly adds to processing time.

We have tested ESRI GRIDs and File Geodatabase Rasters most thoroughly as output formats, though other standalone raster formats should work as well. Problems tend to arise (if at all) when the attribute tables start to reach format limits. Please let us know if you experience problems.

The output table will contain ancillary class values, the count of the number of pixels in that class, and a new column with floating-point type called PRESETDENS, which represents estimated people per pixel. It is most common for this function to be used to specify zero population for certain classes (it's often a safe assumption that water or snowfield areas have zero population). Setting such classes to zero helps refine density estimates in the intelligent dasymetric mapping. You may finish preparing this table in at least two ways:

The first way to populate this table is to add it to ArcMap, start an edit session with the table as the target, and type density values into the PRESETDENS column, then save and stop the edit session.

If you choose a standalone .dbf file as the output for this tool, you may also use Microsoft Excel as an editor for the table. If you choose this option, please be sure to only edit the one column, and save the document as dbf again.

You should remove rows from the table corresponding to those classes for which you do not wish to provide estimates (you would prefer their densities to be calculated via intelligent dasymetric mapping).

Command line syntax

Model <Population_Features> <Population_Count_Field> {Population_Key_Field} <Population_Raster> <Population_Working_Table> {CELL_CENTER | MAXIMUM_AREA | MAXIMUM_COMBINED_AREA} <Ancillary_Raster> <Ancillary_Preset_Table> <Dasymetric_Raster> <Dasymetric_Working_Table>

Parameters

Expression	Explanation
<Population_Features>	The population input polygon featureclass to be converted to a raster.
<Population_Count_Field>	Specify the field in the population dataset that contains count data.
{Population_Key_Field}	Since the tool will always use the system-recognized ObjectID field for the output raster Values, this is for your reference only and is not used by the tool. It can be helpful to have another key field (commonly census FIPS code) for joining the outuput raster to other tables.
<Population_Raster>	The output population raster dataset that will be created, inlcuding the full path. When you're not saving to a geodatabase, specify .tif for a TIFF file format, .img for an ERDAS IMAGINE file format, or no extension for a GRID file format.
<Population_Working_Table>	The tool will create a standalone table for performing calcluations. Please enter a name and path for the output table.
{CELL_CENTER \| MAXIMUM_AREA \| MAXIMUM_COMBINED_AREA}	The method to determine how the cell will be assigned a value when more than one feature falls within a cell. CELL_CENTER—The polygon in which the center of the cell yields the attribute to assign to the cell. MAXIMUM_AREA—The single feature with the largest area within the cell yields the attribute to assign to the cell. MAXIMUM_COMBINED_AREA—Features with common attributes are combined to produce a single area within the cell in question for consideration when determining the largest area.
<Ancillary_Raster>	The ancillary raster dataset to be used to redistribute population. The output raster from this tool will be snapped to the ancillary raster and have matching spatial reference and cell size. Land-use or land-cover are the most frequently used ancillary datasets, but any dataset that has classes of relatively homogenous population density could be used here.
<Ancillary_Preset_Table>	The output standalone table with full path that will be created. If your workspace is a geodatabase, no file extension is necessary, otherwise, please be sure to include a .dbf extension.
<Dasymetric_Raster>	Enter a name and full path for the output dasymetric raster. A common choice is dasyraster. This raster will have a single value for each unique combination of population units and ancillary classes. When you're not saving to a geodatabase, specify .tif for a TIFF file format, .img for an ERDAS IMAGINE file format, or no extension for a GRID file format.
<Dasymetric_Working_Table>	Enter a name and full path for the output dasymetric working table A common choice is dasyworktable. Performing calculations on a standalone table is more predictable than trying to perform calculations on a raster value attribute table. If your workspace is a geodatabase, no file extension is necessary, otherwise, please be sure to include a .dbf extension.

Scripting syntax

Model (Population_Features, Population_Count_Field, Population_Key_Field, Population_Raster, Population_Working_Table, Cell_Assignment_Type, Ancillary_Raster, Ancillary_Preset_Table, Dasymetric_Raster, Dasymetric_Working_Table)

Parameters

Expression	Explanation
Population Features (Required)	The population input polygon featureclass to be converted to a raster.
Population Count Field (Required)	Specify the field in the population dataset that contains count data.
Population Key Field (Optional)	Since the tool will always use the system-recognized ObjectID field for the output raster Values, this is for your reference only and is not used by the tool. It can be helpful to have another key field (commonly census FIPS code) for joining the outuput raster to other tables.
Population Raster (Required)	The output population raster dataset that will be created, inlcuding the full path. When you're not saving to a geodatabase, specify .tif for a TIFF file format, .img for an ERDAS IMAGINE file format, or no extension for a GRID file format.
Population Working Table (Required)	The tool will create a standalone table for performing calcluations. Please enter a name and path for the output table.
Cell Assignment Type (Optional)	The method to determine how the cell will be assigned a value when more than one feature falls within a cell. CELL_CENTER—The polygon in which the center of the cell yields the attribute to assign to the cell. MAXIMUM_AREA—The single feature with the largest area within the cell yields the attribute to assign to the cell. MAXIMUM_COMBINED_AREA—Features with common attributes are combined to produce a single area within the cell in question for consideration when determining the largest area.
Ancillary Raster (Required)	The ancillary raster dataset to be used to redistribute population. The output raster from this tool will be snapped to the ancillary raster and have matching spatial reference and cell size. Land-use or land-cover are the most frequently used ancillary datasets, but any dataset that has classes of relatively homogenous population density could be used here.
Ancillary Preset Table (Required)	The output standalone table with full path that will be created. If your workspace is a geodatabase, no file extension is necessary, otherwise, please be sure to include a .dbf extension.
Dasymetric Raster (Required)	Enter a name and full path for the output dasymetric raster. A common choice is dasyraster. This raster will have a single value for each unique combination of population units and ancillary classes. When you're not saving to a geodatabase, specify .tif for a TIFF file format, .img for an ERDAS IMAGINE file format, or no extension for a GRID file format.
Dasymetric Working Table (Required)	Enter a name and full path for the output dasymetric working table A common choice is dasyworktable. Performing calculations on a standalone table is more predictable than trying to perform calculations on a raster value attribute table. If your workspace is a geodatabase, no file extension is necessary, otherwise, please be sure to include a .dbf extension.

Name	Explanation
Raster 1 - Population Features to Raster
Raster 2 - Combine Population and Ancillary Rasters
Raster 3 - Create Ancillary Class Preset Table

RasterScripts 1-3 - Prepare for Dasymetric Calc

Usage Tips

Command line syntax

Scripting syntax

Model