Changes between Version 39 and Version 40 of WKTRaster/Documentation01

Timestamp:

Dec 10, 2009, 9:18:19 AM (15 years ago)

Author:

pracine

Comment:

—

WKTRaster/Documentation01

@@ -299 +299 @@
 This regular tiling (or regular blocking) is expected from arrangements c) d) and e) in figure 1. PostGIS WKT Raster provides this mechanism because raster applications are often optimized to deal with these arrangements. There is, however, no mechanism to enforce (constrain) these criteria and, as mentioned above, adding, modifying or deleting a row from the table might break this regular blocking, and the regular_blocking attribute will not be automatically updated.
 
+Structure of the "raster" Type
+
+Like the geometry type, the raster type is a complex PostgreSQL type composed of many attributes accessible using various functions. A raster attribute may be composed of many bands sharing a common size, pixel size and georeference. Each band has a pixel type and may have a nodata value.
+
+Table 2 summarizes the composition of a raster type.
+
+
+'''''Table 2 - Structure of a raster type'''''
+
+|| '''Attribute''' || '''Description''' || '''Storage''' || '''Accessible with function...''' ||
+|| '''version''' || WKB format version (now 0). || unsigned 16 bit integer || Not accessible. ||
+|| '''number of bands''' || Number of raster bands stored in the raster. || unsigned 16 bit integer || ST_NumBands() ||
+|| '''width''' || Width of the raster. || unsigned 16 bit integer || ST_Width() ||
+|| '''height''' || Height of the raster. || unsigned 16 bit integer || ST_Height() ||
+|| '''Georeference information''' ||
+|| '''pixelsizex''' || Pixel size in the x-direction in the same map units as the coordinate system. Same as parameter A in a world file. || 64 bit double || ST_PixelSizeX() ||
+|| '''pixelsizey''' || Pixel size in the y-direction in the same map units as the coordinate system. Same as parameter E in a world file. || 64 bit double || ST_PixelSizeY() ||
+|| '''upperleftx''' || X-coordinate of the center of the upper left pixel. Same as parameter C in a world file. || 64 bit double || ST_UpperLeftX() ||
+|| '''upperlefty''' || Y-coordinate of the center of the upper left pixel. Same as parameter F in a world file. || 64 bit double || ST_UpperLeftY() ||
+|| '''rotationx''' || Rotation about x-axis. Same as parameter B in a world file. || 64 bit double || ST_RotationX() ||
+|| '''rotationy''' || Rotation about y-axis. Same as parameter D in a world file. || 64 bit double || ST_RotationY() ||
+|| '''srid''' || Spatial reference id. || 32 bit integer || ST_SRID() ||
+|| '''Band information''' (one set per band) ||
+|| '''isoffline''' || Flag specifying if the band data is stored in the database or as a file in the file system. || 1 bit || If ST_BandPath() return an empty string, the data is stored in the database. ||
+|| '''hasnodatavalue''' || Flag specifying if the stored nodatavalue is significant or not. || 1 bit || ST_BandHasNoDataValue() ||
+|| '''pixeltype''' || Pixel type for this band. || 4 bits || ST_BandPixelType() ||
+|| '''nodatavalue''' || Nodata value for the band. || Depend on band pixel type. || ST_BandNodataValue() ||
+|| '''Band data''' (one set per band) for '''in-db''' raster ||
+|| '''values[]''' || Value of each pixel. || Depends on band pixel type. || ST_ Value() ||
+|| '''Band data''' (one set per band) for '''out-db''' raster ||
+|| '''bandnumber''' || Number of the out-db band. || unsigned 8 bit integer || Not accessible yet. ||
+|| '''path''' || Path to the out-db raster file. || string || ST_BandPath() ||
+
+
+
 
 == '''3.2 - Integration with PostGIS''' ==