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PolarDB:Basic concepts

Last Updated:Oct 09, 2026

This topic introduces the basic concepts related to Raster SQL.

TermDescription
raster objectThe raster that is short for a raster object. It is regular grids into which space is divided. Each grid is called a cell. Each cell is assigned an attribute value to represent a data model of an entity. A raster object can be a satellite image, digital elevation model (DEM), or picture.
cell/pixelThe raster cell. It is also called a pixel. This indicates that a cell is a grid in a raster object. Each cell can have different data types, such as Byte, Short, Int, Double.
bandThe raster band. A band is a single matrix of cell values in a raster object. A raster object can have multiple bands.
chunkThe raster chunk. You can customize the size of a chunk, such as 256 × 256 × 3.
pyramidThe raster pyramid. The downsampled version of a source raster object. A pyramid can contain multiple downsampled layers. Consecutive pyramid layers are downsampled at a scale of 2:1. Layer 0 stores the raw data.
pyramid levelThe layer of a raster pyramid.
mosaicThe operation to integrate multiple raster objects into an existing raster dataset.
interleavingThe interleaving method of pixels in a raster. The interleaving methods are band sequential (BSQ), band interleaved by pixel (BIP), and band interleaved by line (BIL).
world spaceThe world coordinate space. It indicates the geographic coordinate space of a raster object.
raster spaceThe coordinate space of a raster. It indicates the pixel coordinate space of a raster object. The upper-left corner of the raster is used as the starting point.
metadataThe metadata of a raster, including the spatial range, projection type, and pixel type. The metadata of the remote sensing platform is excluded.