What kinds of problems do you learn to solve with Image Classification and Land Cover?
- How do you convert satellite images into reliable maps of land cover and land use?
- How do you automatically distinguish between vegetation, water, soil, and built-up areas?
- Which classification method is best suited for a specific type of satellite image and spatial problem?
- How do you select representative training data for reliable classification?
- How do you assess and validate the quality and accuracy of a classification result?
In this Blended Learning course, you’ll learn how to convert satellite images into usable land-cover information. You’ll learn to apply various classification methods, evaluate results, and translate classifications into reliable maps that can be used for nature conservation, agriculture, water management, urban development, and monitoring changes in the landscape, among other applications.
The Theory Behind Image Classification
A satellite image consists of pixels with measured values in different spectral bands. Different types of land cover each have their own spectral properties. For example, vegetation reflects radiation differently than water, bare soil, or buildings. These differences form the basis for the automatic classification of satellite images.
You’ll learn how pixels can be categorized into different classes based on their spectral properties. You’ll also be introduced to concepts such as features, classes, training data, decision rules, and classification models. You’ll also learn the difference between land cover and land use and why this distinction is important when interpreting classification results.
From Satellite Image to Land-Cover Classes
In image classification, you determine which category a pixel or group of pixels belongs to. You’ll learn how different spectral bands, band combinations, and derived information can be used to better distinguish between classes.
You’ll be introduced to supervised and unsupervised classification. In supervised classification, you use known examples to train a model to recognize which characteristics belong to a particular class. In unsupervised classification, pixels are automatically grouped based on similarities, after which you investigate what these groups represent in the landscape.
Above all, you’ll learn to assess which approach is best suited to the problem at hand, the available satellite data, and the desired land-cover map.
Training Data and Classification Methods
The quality of a classification is strongly determined by the quality of the data used. That is why you’ll learn how to select representative training areas and how to prevent classes from being too similar spectrally or from being underrepresented.
You’ll be introduced to various classification methods and learn to compare their results. In doing so, you’ll explore how the choice of spectral bands, training data, and classification method influences the final result.
For the analyses, you’ll work with open satellite data and open-source software. QGIS serves as the central working environment, and where relevant, specialized open-source algorithms—such as those from the Orfeo ToolBox—can be used. However, the software itself is not the starting point; the central focus is always on how to achieve a reliable classification.
Assessing and Validating Classifications
A land-cover map is only useful if you know how reliable the classification is. That is why you will learn to critically evaluate classification results and compare them with independent reference data.
You’ll be introduced to validation techniques such as confusion matrices and accuracy metrics for individual classes and for the classification as a whole. You’ll investigate where errors occur, which classes are often confused with one another, and how training data or the chosen method can be improved.
In this way, you’ll not only learn how to perform a classification but also how to substantiate the reliability of the results and determine for which applications the map is—or isn’t—suitable.
From Classification to Useful Land-Cover Information
During the Blended Learning course, you’ll work with realistic satellite images and open datasets. You’ll use image classification to reveal spatial patterns and derive land-cover information that can be used for analysis and decision-making.
You’ll work on assignments such as:
- Classify a satellite image into land-cover classes such as water, vegetation, soil, and built-up areas.
- Compile suitable training data and assess how it affects the quality of the classification.
- Compare different classification methods and determine which approach yields the best results.
- Identify which classes are difficult to distinguish from one another and explain why.
- Validate a classification using independent reference data and assess the accuracy of the results.
- Create a land-cover map and translate the results into conclusions for a spatial issue.
Upon completion, you will be able to independently classify satellite images and convert them into reliable land-cover information. You will be able to select an appropriate classification strategy, evaluate training data, validate results, and use land-cover maps to analyze spatial patterns and trends.