Raster Data Model Quiz

Raster Data Model

• Represents the world as a continuous field, unlike vectors which use discrete objects
• Useful for phenomena that vary continuously (e.g., temperature, elevation, land cover)

Key Features

• Grid-based representation: divides space into square grid cells (or lattice)
  • Each cell stores an attribute/value for that location
  • Different from vector models that use points, lines, or polygons
• Spatial Resolution: Size of grid cells (measured in ground distance)
  • Finer resolutions (smaller cells) capture more detail but require more storage
  • Spatial extent is the total area covered by the raster
• Attribute Storage: Each layer stores one variable only
  • Qualitative data: Categorical (e.g., land use types)
  • Quantitative data: Numerical (e.g., elevation, temperature)
• Geo-referencing: Cells positioned using the X,Y coordinate of the top-left cell
  • The spatial position of other cells is calculated based on cell size, rows, columns, and order

Types of Raster Data

• Binary: Two values (e.g., 0 for absence, 1 for presence)
• Integer: Whole numbers (representing categories or rounded quantitative data)
• Floating-point: Decimal precision (e.g., rainfall, temperature)
• Character: (less common) strings or letters for qualitative data

Raster Data Structure

• Header: Contains info like number of rows/columns, cell size, and starting coordinates
• Cell Order/Storage: Attributes stored row by row, left-to-right, starting from the top-left corner (order can vary depending on the format)
• Storage Efficiency: Stores only one coordinate for the entire layer (Unlike vectors), making reconstruction faster and more efficient

Important Takeaways

• Ideal for continuous phenomena, with separate layers for each attribute
• Spatial resolution determines detail, and extent refers to the total area
• Computationally efficient due to simple structure (store one coordinate efficiently)
• The type of raster data influences its uses (e.g., from simple presence/absence maps to detailed quantitative analyses)

Test your knowledge on the Raster Data Model and its key features. This quiz covers concepts such as grid-based representation, spatial resolution, attribute storage, and geo-referencing. Ideal for students and professionals in geography and environmental sciences.