Y rotation relative to the negative y axis X rotation relative to the positive x axis Rotation is measured in radians, counter-clockwise: Represents the rotation of a raster relative to the x and y axes.Ġ,0 means no rotation – the raster is aligned straight along both axes. Also known as cell size.įor georeferenced rasters, spacing is in ground units. Some formats store only one spacing value, requiring square cells. X and y coordinates, in ground units, of the upper left corner of the raster.įixed distance in the x and y dimensions between each cell in the raster. Total number of columns (x-axis) and rows (y-axis). X and y coordinates, in ground units, of the upper right corner of the raster. X and y coordinates, in ground units, of the lower left corner of the raster. These properties have a single value per raster, and describe the raster as a whole. If a raster is georeferenced, these corner x and y coordinates will reflect the units of the raster’s coordinate system (meters or degrees, for example). This differs from its geographical extents, which are described from the lower left to upper right corners. Raster PropertiesĪ raster’s origin with regards to its own columns and rows is the upper left corner. An RGBA (with alpha) with 16-bit bands (Red16, Green16, Blue16, Alpha16) is RGBA64. An RGB raster with 8-bit bands (Red8, Green8, Blue8) is RGB24. (See Band Interpretation Type below.)Ī single-band raster is described by the same interpretation type as that one band.Ī color raster is described as its color and alpha components, along with the sum of bit depths for all bands. Raster Interpretation TypesĪ raster’s interpretation type reflects its bands’ interpretation types. They will also have a series of attributes that are specific to their format, prefixed appropriately with strings such as geotiff_, pngraster_, cded_, ngrid_, and so on. In FME, rasters have these attributes and values: Some may be associated with a geographic feature and stored as an attribute, common with scanned documents and images. Some may be tied to a point on the earth (as is a photo with embedded GPS information) but the contents of the image are not georeferenced. Some, such as scanned maps, can be manually georeferenced. Some rasters are georeferenced, and know where they are positioned on the earth. The number of bands will vary – one for a digital elevation model (DEM) or simple numeric raster, three or four for most color image rasters (red, green, blue, and sometimes alpha), and even more for those produced with multiple sensors or representing measurements repeated over time. Images are commonly derived from satellite data or photography, while numeric data often represents elevations, temperatures, and other quantitative information. Rasters may represent image or numeric data. A band’s interpretation determines what range and type of values it can hold.Įach cell has one numeric value per band. A raster is a rectangular matrix of evenly-spaced cells (sometimes called pixels), arranged in columns and rows.Ī raster – and therefore its cells – has one or more bands (sometimes called channels or layers).
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