Hue Index

Color index representing the dominant wavelength in visible spectrum. Used for color analysis and classification of materials based on their spectral hue characteristics. Urban and built-up indices distinguish impervious surfaces from natural land cover by leveraging the unique spectral properties of construction materials like concrete, asphalt, and metal roofing. H is particularly suited for color analysis, material classification, urban mapping. The general formula is arctan((2 * Red - Green - Blue) / (30.5 * (Green - Blue))), which requires Red and Green and Blue spectral bands.

H is supported by 23 satellite sensors in our database, including BJ3A, BJ3N, Dragonette-1, Dragonette-2/3, Gaofen-1 and 18 more. Each sensor uses different band designations — for example, BJ3A uses the formula arctan((2 * Red - Green - Blue) / (30.5 * (Green - Blue))), while BJ3N uses arctan((2 * Red - Green - Blue) / (30.5 * (Green - Blue))). Select a sensor above to see its specific band mapping.

H requires Red (630-690 nm), Green (530-590 nm), Blue (450-515 nm). These wavelength regions target the specific spectral features that this index is designed to measure.

Both Python and R code samples are provided above. In Python, use rasterio to load individual band GeoTIFF files and numpy for the arithmetic. In R, the terra package handles raster operations efficiently. The key is to load bands as floating-point arrays to avoid integer division, and to handle division-by-zero cases where the denominator equals zero. For production use, consider applying a valid data mask to exclude no-data pixels before calculation.