Digital image processing

Digital image processing in remote sensing involves the manipulation of satellite or aerial images to extract useful information about the Earth's surface. Here are the basic steps involved:

1. Image Acquisition: Remote sensing devices, such as satellites and aerial cameras, capture images of the Earth's surface. These images are usually in digital format and consist of pixels, each representing a small portion of the Earth's surface.

2. Preprocessing: This step involves the initial cleaning and enhancement of the raw image data. It includes tasks like radiometric calibration to correct for sensor-related distortions and atmospheric correction to account for the effects of the Earth's atmosphere on the image.

3. Image Enhancement: Enhancement techniques like contrast adjustment, histogram equalization, and filtering are used to improve the visual quality of the image and make important features more discernible.

4. Image Registration: Multiple images from different sources or times may need to be aligned or registered to ensure accurate analysis. This step involves geometric correction to match images to a common coordinate system.

5. Image Transformation: Spatial and spectral transformations may be applied to the image data to enhance specific features or extract relevant information. This can include techniques like image fusion, pan-sharpening, and principal component analysis (PCA).

6. Feature Extraction: This step involves identifying and isolating specific objects or features within the image. Techniques such as edge detection, classification, and object recognition are used to extract information about land cover, vegetation, water bodies, and more.

7. Image Analysis: Once features are extracted, various analytical methods are applied to interpret the data. This can involve measuring land cover changes, monitoring environmental conditions, or identifying patterns and trends.

8. Post-processing: After analysis, additional steps like noise reduction, mosaicking (combining multiple images), and creating thematic maps may be performed to produce final output products.

9. Interpretation and Decision Making: Remote sensing experts interpret the processed images and extract meaningful information for various applications, such as agriculture, forestry, urban planning, disaster management, and environmental monitoring. The results help in informed decision-making.

10. Reporting and Visualization: The final processed data and analysis results are often presented through maps, reports, and visualizations, making it easier for stakeholders to understand and utilize the information.

Digital image processing plays a crucial role in remote sensing by enabling the extraction of valuable insights from satellite and aerial imagery, which can be used for a wide range of scientific, environmental, and practical applications.

Comments

History of GIS

1. 1832 - Early Spatial Analysis in Epidemiology: - Charles Picquet creates a map in Paris detailing cholera deaths per 1,000 inhabitants. - Utilizes halftone color gradients for visual representation. 2. 1854 - John Snow's Cholera Outbreak Analysis: - Epidemiologist John Snow identifies cholera outbreak source in London using spatial analysis. - Maps casualties' residences and nearby water sources to pinpoint the outbreak's origin. 3. Early 20th Century - Photozincography and Layered Mapping: - Photozincography development allows maps to be split into layers for vegetation, water, etc. - Introduction of layers, later a key feature in GIS, for separate printing plates. 4. Mid-20th Century - Computer Facilitation of Cartography: - Waldo Tobler's 1959 publication details using computers for cartography. - Computer hardware development, driven by nuclear weapon research, leads to broader mapping applications by early 1960s. 5. 1960 - Canada Geograph...

Accuracy Assessment

Accuracy assessment is the process of checking how correct your classified satellite image is . 👉 After supervised classification, the satellite image is divided into classes like: Water Forest Agriculture Built-up land Barren land But classification is done using computer algorithms, so some areas may be wrongly classified . 👉 Accuracy assessment helps to answer this question: ✔ "How much of my classified map is correct compared to real ground conditions?" Goal The main goal is to: Measure reliability of classified maps Identify classification errors Improve classification results Provide scientific validity to research 👉 Without accuracy assessment, a classified map is not considered scientifically reliable . Reference Data (Ground Truth Data) Reference data is real-world information used to check classification accuracy. It can be collected from: ✔ Field survey using GPS ✔ High-resolution satellite images (Google Earth etc.) ✔ Existing maps or survey reports 🧭 Exampl...

Supervised Classification

Image Classification in Remote Sensing Image classification in remote sensing involves categorizing pixels in an image into thematic classes to produce a map. This process is essential for land use and land cover mapping, environmental studies, and resource management. The two primary methods for classification are Supervised and Unsupervised Classification . Here's a breakdown of these methods and the key stages of image classification. 1. Types of Classification Supervised Classification In supervised classification, the analyst manually defines classes of interest (known as information classes ), such as "water," "urban," or "vegetation," and identifies training areas —sections of the image that are representative of these classes. Using these training areas, the algorithm learns the spectral characteristics of each class and applies them to classify the entire image. When to Use Supervised Classification: - You have prior knowledge about the c...

Development and scope of Environmental Geography and Recent concepts in environmental Geography

Environmental Geography studies the relationship between humans and nature in a spatial (place-based) way. It combines Physical Geography (natural processes) and Human Geography (human activities). A. Early Stage 🔹 Environmental Determinism Concept: Nature controls human life. Meaning: Climate, landforms, and soil decide how people live. Example: People in deserts (like Sahara Desert) live differently from people in fertile river valleys. 🔹 Possibilism Concept: Humans can modify nature. Meaning: Environment gives options, but humans make choices. Example: In dry areas like Rajasthan, people use irrigation to grow crops. 👉 In this stage, geography was mostly descriptive (explaining what exists). B. Evolution Stage (Mid-20th Century) Environmental problems increased due to: Industrialization Urbanization Deforestation Pollution Geographers started studying: Environmental degradation Resource management Human impact on ecosystems The field became analytical and problem-solving...

GIS: Real World and Representations - Modeling and Maps

Geographic Information Systems (GIS) serve as a bridge between the real world and digital representations of geographic phenomena. These representations allow users to store, analyze, and visualize spatial data for informed decision-making. Two key aspects of GIS in this context are modeling and maps , both of which are used to represent real-world geographic features and phenomena in a structured, analyzable format. Let's delve into these concepts, terminologies, and examples in detail. 1. Real World and Representations in GIS Concept: The real world comprises physical, tangible phenomena, such as landforms, rivers, cities, and infrastructure, as well as more abstract elements like weather patterns, population densities, and traffic flow. GIS allows us to represent these real-world phenomena digitally, enabling spatial analysis, decision-making, and visualization. The representation of the real world in GIS is achieved through various models and maps , which simplify...

Vineesh V, Geography

Search This Blog