NR 322: Attributes Jim Graham Fall 2010 Chapter 2

Cartography DEM -> “Elevation” Legend –Should only have “Elevation” –Consitent capitalization and plurals Contract with background –Typically background will be light (pastels) and other content will be dark –Dark background implies other content must be light (pastels) Watch gaps!

Attributes Table attached to each layer Each row tied to a feature –Point –Polyline(s) –Polygon(s) Each column represents a different attribute

Attributes Vector Attributes (very common) Raster Attributes (when available) Examples of attributes: –Name –Population/Census numbers –Vegetation characteristics –Dates –Coordinates –Ownership –Park Type

Vector Attributes Used For: –Labels: Direct Results of “expressions” –Symbology –Selection –Sub-setting

Data Types Qualitative –Nominal: No order, types Quantitative –Ordinal: Ordered set of classifications –Interval: Values along arbitrary scale –Ratio: Values along non-arbitrary scale –Cyclic: Values repeat

Data Types Qualitative –Nominal: Land Cover Type Quantitative –Ordinal: Fire danger low, medium, high –Interval: Temperature –Ratio: DBH (floating point) –Cyclic: Directions (0 to 360 degrees)

Data Types Date: mm/dd/yyyy hh:mm:ss Integers: –Short: 16-bit (2-bytes): to –Long: 32-bit (4-bytes): -2 billion to 2 billion Floating point (real numbers): –Float: 7 significant digits –Double: 15 significant digits Text: –Up to 255 characters

Examples of Attributes Names Taxonomic Identification: –Scientific Names, common names, codes (NRCS codes) Organism characteristics Population values Distance, Area Dates Collector’s names Coordinates

Coordinate Attributes It is common to see Lat/Lon or Easting/Northing in attribute tables for point layers These are not the values used to render the spatial data! These values are not updated when you project, edit, or transform the spatial data! To update these columns…

Attribute Files *.shp – Spatial data *.dbf – dBase file can be opened in Excel *.xml – Metadata should describe the attributes

Finding Data Searched on: Colorado oil well data Shapefile Searched on: Deer Shapefile – S/disclaim.htmhttp://dwrcdc.nr.utah.gov/ucdc/DownloadGI S/disclaim.htm – /181/group214.htmlhttp://data.geocomm.com/catalog/US/61047 /181/group214.html Searched on: Fort Collins Shapefile

Lab Import points from X,Y file Add polygon, polygon Label based on attributes –One calculation Add Raster data –Classify based on attributes What is the value of a raster pixel at a point?