AcATaMa

Thematic maps are essential tools for understanding and managing land-cover and land-use change. However, their effectiveness depends on map accuracy, which is critical to environmental monitoring, resource management, and policy making. The accuracy assessment of raster thematic maps involves a rigorous process of sampling, response design, and analysis to ensure that maps accurately reflect true conditions on the ground.

AcATaMa is a QGIS plugin designed to provide comprehensive support for accuracy assessment and sample-based area estimation of raster thematic maps. The plugin enables users to comply with international standards and best practices in accuracy assessment, integrating three fundamental components: sampling design (supporting simple random, stratified random, and systematic sampling), response design (providing a multi-window interface for reference data interpretation), and analysis (generating error matrices, accuracy metrics, and area-adjusted estimates with uncertainty quantification).

The Three Components

The accuracy assessment of thematic maps consists of three key components: sampling design, response design, and analysis. AcATaMa integrates these components through a structured, sequential workflow.

1. Sampling Design

The sampling design determines how sample units are selected to ensure representativeness and statistical validity [Stehman and Czaplewski, 1998]. A well-structured sampling design is essential for producing unbiased accuracy estimates and reliable area estimates.

2. Response Design

The response design involves defining the procedures for obtaining and interpreting reference classifications, ensuring that the comparison between map and reference data is reliable [Olofsson et al., 2014]. It encompasses the protocols and methodologies used to determine the reference or “true” classification of sampled units.

3. Analysis

Analysis involves quantifying accuracy through error matrices and statistical metrics and estimating class areas with confidence intervals, ensuring scientifically rigorous conclusions [Stehman and Czaplewski, 1998, Olofsson et al., 2014].

Note

Each component is explained in detail in the following pages.

Modular Usage

Although AcATaMa is designed to follow a sequential three-step workflow for accuracy assessment, the sampling and response design modules can also be used independently for other purposes:

• Sampling design: Can be used alone to generate random samples for establishing field plots

• Response design: Can be used alone to assign reference labels to point layers using multi-source remote sensing and ancillary geospatial data