Biological Systems Engineering

CS Suite

Polygon Attribute Table

The following tables show a portion of a polygon attribute table that was used in a GIS project.

This table was produced by an Arc/Info overlay operation in which a map of soils and a map of weather locations were overlayed to produce a combined simulation map with this respective table. The Arc/Info IDENTITY command was use to produce a combined simulation map.

Polygon attribute tables always have at least four attributes or table column labels.

  • AREA and PERIMETER are computed by the GIS software. These are not currently used by the Coöperator or Watershed simulations.

  • There will be an attribute having the same name as the coverage with an underscore "_" concatenated. (For example if the name of the coverage is SOIL, the attribute will be named SOIL_). The unique numbers in this column enumerate each polygon. This number is assigned as polygons are identified by the GIS software.

  • There will be an attribute having the same name as the coverage with an underscore "_ID" concatenated. This number is assigned either by the user or by a GIS command that generated the map coverage. This number is not unique. In this example, in the soil map the number is used to identify the type of the soil found in the polygon not necessarily a unique identifier of the polygon. However, in the COMBSIM coverage which is generated by the IDENTITY command, the COMBSIM_ID will be unique. This column will be used by the Coöperator and Watershed simulations to organize simulations and output files generated by the simulations. (You can also use COMBSIM_, but we recommend using the COMBSIM_ID field for consistancy).

In addition to these four attributes which are always present in the table, there will very likely be other attributes containing user supplied information. The user can add any number of such attributes. In this example the soil map has the field SOIL and the weather region map has the field LOCATION. These fields correspond in this example to codes used to identify CropSyst parameter files associated with the respective polygons. You will need to add such attributes to your coverages and assign the respective code/filename to each polygon.

For polygons which are not intended for simulation, any code/filename for which there is no corresponding CropSyst parameter file will cause the Coöperator or Watershed simulation to omit the polygon from the simulation (this is not an error condition, but such polygons will be noted in the simulation log). In this example, the codes UNKNOWN, URBAN, INDUSTRIAL are used in the soil map to identify polygons with no soil data. No soil files are created having these file names, so any polygons thusly named with be omitted from the simulation. Blank entries will also be excluded.

The parameters files used in the GIS and Watershed project simulations are normal CropSyst parameter files.

You will need to have all the parameter files that may be specified in the combined simulation map polygon attribute table. Any parameter file that is missing will cause the Coöperator or Watershed simulator to skip the run and tally of that polygon since the simulation will assume the polygon to be an "offsite" area.

Note that there will be a polygon (Usually the first entry in the table) with a negative area. This is the rectangular polygon bounding the extent of the coverage. This polygon should usually be assigned an UNKNOWN code.

 

Combined simulation map (COMBSIM) polygon attribute table (extract).
AREA PERIMETER COMBSIM_ COMBSIM_ID REGION_ID LOCATION SOIL_ID SOIL
-1576586000.000000 224853.900000 1 0 0 0 UNKNOWN
269391500.000000 245091.500000 2 1 1 paderna 0 UNKNOWN
765547.400000 6171.758000 3 2 1 paderna 1 URBAN
46941.510000 1028.909000 4 3 1 paderna 2 CAS1
517171.300000 4276.688000 5 4 1 paderna 3 CAS1
9337191.000000 13752.080000 6 5 1 paderna 4 CAS1
1454818.000000 11556.710000 7 6 1 paderna 5 INDUSTRIAL
: : : : : : : :
151128800.000000 206153.800000 68 67 2 modena 0 UNKNOWN
5603472.000000 11995.560000 69 68 2 modena 64 RSD1
2689567.000000 9137.461000 70 69 2 modena 65 CAS1
6940745.000000 21426.680000 71 70 2 modena 66 SMB2
: : : : : : : :
This is only a portion of an actual table which had may hundered polygons. There will also be columns SOIL_ and REGION_ carried from the overlay operation which are not used by the Coöperator or Watershed simulations.

 

Soil map (SOIL) polygon attribute table.
AREA PERIMETER SOIL_ SOIL_ID SOIL
-1576586000.000000 224853.900000 1 0 UNKNOWN
3529891500.000000 245091.500000 2 0 UNKNOWN
543447.400000 6171.758000 3 1 URBAN
64441.510000 1028.909000 4 2 CAS1
134171.300000 4276.688000 5 3 CAS1
3457191.000000 13752.080000 6 4 CAS1
5464818.000000 11556.710000 7 5 INDUSTRIAL
: : : : :
346128800.000000 206153.800000 40 0 UNKNOWN
1243472.000000 11995.560000 41 64 RSD1
1234567.000000 9137.461000 42 65 CAS1
3452745.000000 21426.680000 43 66 SMB2
: : : : :

 

Weather region (REGION) map polygon attribute table.
AREA PERIMETER REGION_ REGION_ID LOCATION
-1576586000.000000 234224853.900000 1 0
5245824900.000000 435245091.500000 2 1 paderna
634568-908.000000 656406153.800000 3 2 modena

 

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Development by:

Dr. Claudio O. Stöckle

Roger Nelson

 

Contributors:

Corina Fernandez

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