Polygonize Raster to Vector | How to Polygonize Rasters using QGIS | Raster to Vector Conversion

Описание: In Geographic Information Systems (GIS), "polygonize" refers to the process of converting raster data or other vector data types into polygons. This operation is commonly used when you want to represent continuous or categorical information as polygon features with distinct boundaries.
Raster to Polygon Conversion: When you polygonize a raster, you take a raster dataset (which consists of cells or pixels with different values) and create polygons that enclose areas of contiguous cells with the same value. Each polygon represents a distinct category or class from the original raster.
In the context of raster data, especially in remote sensing and digital image processing, "DN" stands for "Digital Number." Digital Number refers to the discrete numeric values that represent the pixel intensity or radiometric value of each cell or pixel in a raster image.
The DNs in a raster image are used to represent various types of information, depending on the type of sensor and the specific application. For example, in a multispectral satellite image, DNs can represent the reflectance values of different spectral bands, allowing you to distinguish between land cover types, monitor vegetation health, or perform other types of image analysis.
Common use cases for polygonization in GIS include:
Land Cover Classification: Converting a land cover raster into polygon features representing different land cover classes (e.g., forests, urban areas, water bodies).
Watershed Delineation: Creating polygons that represent watershed boundaries from a raster representing elevation or flow accumulation.
Parcelization: Converting a raster of cadastral or land parcel information into vector polygons representing individual land parcels.
Thematic Mapping: Transforming continuous raster data (e.g., temperature, elevation) into thematic maps with distinct polygon features representing categorized ranges of values.
Feature Extraction: Converting satellite or aerial imagery into vector polygons to represent specific features, such as buildings, roads, or vegetation.