Data types

1
Data types
2
Grids
x
Origin (x,y)
rows
y
Resolution (cell size)

• Measurement units
• Min x, Max x, Min y, Max y
• Data type

columns
3
Raster vs. Vector representation
Raster (grids)
Vector (shapefiles)

• Continuous surfaces
• Map algebra
• Neighborhood queries
• Images

• Precise boundary definition
• Administrative data (cities, counties), roads
• Network modeling
• Geoprocessing

4
Grid analysis
One-to-one relationship between layers
5
Images

• Aerial photographs, remotely sensed images
• Images are rasters
• Images and grids are handled differently
• Many formats, e.g. tif, bil, MrSid
• Need world file (e.g. tfw) or header to display
  properly