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Quick Start

This guide walks you through your first land use/land cover change analysis in just a few steps.

Prerequisites

Before starting, ensure you have:

  • QGIS 3.28 or higher installed
  • The Spatiotemporal LULC Analysis plugin installed (Installation Guide)
  • Two or more categorical LULC rasters for different years

What are categorical rasters?

Categorical rasters contain integer values where each value represents a land use/land cover class (e.g., 1 = Forest, 2 = Agriculture, 3 = Urban). These are typically derived from satellite imagery classification.

Step 1: Open the Plugin

  1. In QGIS, go to Plugins > Spatiotemporal LULC Analysis
  2. A dock panel will appear on the right side of your screen

Step 2: Add Your Rasters

You can add rasters in two ways:

  1. Click the Add Files button
  2. Navigate to your raster files (.tif, .tiff, or .img)
  3. Select multiple files by holding Ctrl (or Cmd on macOS)
  4. Click Open
  1. First, load your rasters into QGIS
  2. Click the Add From Project button
  3. Select the layers you want to analyze
  4. Click OK

Automatic Year Detection

The plugin automatically extracts years from filenames containing patterns like 2010, 2015, 2020, etc. You can manually edit years in the table if needed.

Step 3: Configure Basic Settings

  1. Output Directory: Click Browse and select where to save results
  2. NoData Value: Choose how to handle NoData:
    • Use raster NoData - Uses the NoData value defined in each raster
    • Override - Enter a custom NoData value
  3. AOI (Optional): Select a polygon layer to limit analysis to a specific area

Step 4: Validate Inputs

Before running the analysis, validate your inputs:

  1. Click the Validate Inputs button
  2. Review the validation results in the Validation tab
  3. Address any FAIL items before proceeding

Common Validation Issues

  • CRS mismatch: All rasters must use the same coordinate reference system
  • Resolution mismatch: Pixel sizes must be identical
  • Extent mismatch: Rasters should cover the same area

Step 5: Run the Analysis

  1. Click the green Run Analysis button
  2. Monitor progress in the progress bar and log panel
  3. Wait for the "Analysis complete" message

Step 6: View Your Results

After analysis completes:

  • CSV files are saved to your output directory
  • Rasters (change frequency, hotspots) are automatically added to QGIS
  • Charts (if enabled) are in the charts/ subdirectory

Quick Output Overview

File Description
area_by_class.csv Area of each class per year
net_gross_change_*.csv Gain/loss per class for each interval
transition_matrix_*.csv Full from-to transition matrix
change_frequency.tif Count of changes per pixel
change_hotspot_*.tif Kernel density hotspot maps
charts/*.html Interactive visualizations

Example Workflow

graph LR
    A[Load Rasters] --> B[Set Output Dir]
    B --> C[Validate]
    C --> D{All Pass?}
    D -->|Yes| E[Run Analysis]
    D -->|No| F[Fix Issues]
    F --> C
    E --> G[View Results]

Next Steps