Raster Analysis: Local Functions Overview

What is the primary focus of local functions in raster analysis?

Which operation is NOT categorized under local functions in raster analysis?

What does binary masking in reclassification assign to represent presence or absence?

Which mathematical operation could convert elevation data from feet to meters?

In logical statements, what is the result of a Boolean AND operation when one condition is false?

What type of analysis calculates the straight-line distance of each cell to the nearest source cell?

Which category consolidates multiple attribute types into fewer classes?

What is the distinction between local functions and more advanced raster analyses?

Raster Operators for Analysis: Local Functions

Raster data model represents continuous data using grid cells, contrasting to object-based vector data model
Raster analysis focuses on local, focal, zonal, and global functions, this lecture focuses on local functions
Local functions analyze data on a cell-by-cell basis

Categories of Local Functions

1. Reclassification

Binary Masking: assigns values (0 or 1) for absence/presence or suitability, often an intermediate step
Classification Reduction: consolidates multiple attribute types into fewer classes, e.g., merging forests
Classification Ranking: assigns ranks/weights for further analysis, like least-cost path analysis

2. Arithmetic Operations

Includes addition, subtraction, multiplication, and division applied to corresponding cells across layers
Example: converting elevation data from feet to meters by multiplying by 0.305

3. Logical Statements

Boolean AND: both conditions must be true for a value of 1; otherwise, the output is 0
Boolean OR: if either condition is true, the value is 1
Logical queries and map algebra can be performed using raster calculators

4. Proximity Analysis

Euclidean Distance: calculates the straight-line distance of each cell to the nearest source cell; useful for analyses like buffering

Key Takeaways

Raster and vector operations are different due to data models
Local functions focus on individual cells or corresponding cells across layers
Local level serves as a foundation for advanced raster analysis (focal, zonal, global)

This quiz explores local functions in raster analysis within the raster data model, focusing on methods like reclassification, arithmetic operations, and logical statements. Understand how these functions operate on a cell-by-cell basis to analyze continuous data effectively.