PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

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Figure 3.2: PostGIS Raster data architecture. Everything is stored in a single attribute and raster attributes composing a table are not necessarily related to each other to form a significant coverage. PostGIS Raster uses in addition a raster_columns table to contain information about which tables have a raster column and the metadata (pixeltype, block size, nodata value and etc.) of the rasters in these columns. 3.2.2 Physical Storage GeoRaster data consists of a multidimensional matrix of cells and the GeoRaster metadata. The multidimensional matrix is blocked into small blocks. A block (or tile) is stored as a BLOB and a geometry object of type SDO\_GEOMETRY is used to define the spatial extent (footprint) of the block. Each block and information related to that block are stored in one row. Thus for storing an image having size greater than block size, at least two rows are necessary to be used in Oracle database table [3]. To do this, GeoRaster requires two types of object: • The SDO_GEORASTER type contains spatial extent geometry and metadata. • The SDO_RASTER contains a BOLB storing a block and the block information. Each SDO_GEOMETRY data has a pair of attributes (rasterDataTable, rasterID) that identify the RDT and the rows within the RDT that are used to store the raster data. For Example, Figure 3.3 shows the storage of GeoRaster object used for an image of Boston, Massachusetts, where: • Each row in the table of city images contains information about the image for a specific city (such as Boston), including an SDO_GEORASTER object. • The SDO_GEORASTER object includes the spatial extent geometry covering the entire area of the image, the metadata, the raster ID and the name of the raster data table associated with this image. • Each row in the raster data table contains information about a block (or tile) of the image, including the block’s minimum bounding rectangle (MBR) and image data (stored as a BLOB). A MBR is defined as a single rectangle that minimally encloses a geometry or a collection of geometries. In PostGIS Raster, the raster type is a complex type composed of many attributes like attribute, georeference information, band information and band data. Thus a single raster attribute can contain all information about raster itself (width, height, number of bands, pixel type for each band, nodata 21
Figure 3.3: Physical storage of GeoRaster data [3]. value and data values for each band) with its georeference (pixel type, upper left pixel center, rotation and spatial reference system identifier (SRID)). A single raster attribute may be composed of many bands having a common size, pixel size and georeference. The storage used for raster bands is band sequential (BSQ) in which each band has its pixel type and its nodata value. One table with a column of type raster is called raster coverage. One table row with a column of type raster is called tile. Thus there are no differences between rasters and tiles. A tile is a raster and a raster is a tile in which each tile has all that are necessary to do basic raster operations. Figure 3.4: Physical storage of PostGIS Raster data. Another important advantage of PostGIS Raster over Oracle GeoRaster is the georeferencing approach [14]. As Oracle GeoRaster uses a one-georeference-by-layer georeference schema instead of one-georeference-by-raster one, so non-continuous raster data cannot be stored in the same raster data table. That means that Oracle GeoRaster requires one raster data table for each raster file loaded when these raster files are from irregular raster coverage. In contrast, PostGIS Raster allows only one table for all kinds of raster coverages, regular or not. In addition to this traditional storing method (storing in-database raster), PostGIS Raster enables user to simply register basic metadata (path to the actual file, pixeltype, with, height, georeference) of images stored in the file system, without having to load their data values into the database. This is 22
Page 1 and 2: Faculté de Sciences Appliquées Se
Page 3 and 4: Abstract Nowadays, in many applicat
Page 5 and 6: 3.2.4 Overlapping Raster and Vector
Page 7 and 8: D.5 Geology, Geophysics and Geochem
Page 9 and 10: 4.9 Raster cell [16]. . . . . . . .
Page 11 and 12: Chapter 1 Introduction 1.1 Context
Page 13 and 14: Chapter 2 Geographic Information Sy
Page 15 and 16: 2.2.3 Imagery Figure 2.3: Polygon f
Page 17 and 18: Figure 2.8: Surface expressed by co
Page 19 and 20: 4-foot logo. The file size is the s
Page 21 and 22: 2.4.2 Data Theme Figure 2.14: Multi
Page 23 and 24: measures of latitude. Longitude mea
Page 25 and 26: 2.6 GIS Applications 2.6.1 Crime Ma
Page 27 and 28: 2.6.3 Traditional Knowledge GIS Tra
Page 29: These additional functionalities ma
Page 33 and 34: DROP INDEX spain_images_idx; CREATE
Page 35 and 36: In summary, the intersection is muc
Page 37 and 38: Attribute information Table 4.1: Po
Page 39 and 40: Figure 4.2: Information representat
Page 41 and 42: for discrete data while floating-po
Page 43 and 44: the matrix are parallel to the x-ax
Page 45 and 46: Lines Figure 4.15: Raster point rep
Page 47 and 48: Choosing an appropriate cell size i
Page 49 and 50: The multi-band conception is result
Page 51 and 52: "32BUI" = 32-bit unsigned integer "
Page 53 and 54: Figure 4.30: Pyramids at different
Page 55 and 56: ectangular because there might be s
Page 57 and 58: Figure 4.39: Vector to raster conve
Page 59 and 60: Figure 4.42: Web application with o
Page 61 and 62: In this example, the dummy_rast tab
Page 63 and 64: One approach to make this intersect
Page 65 and 66: 4.19 Intersection The fact that Pos
Page 67 and 68: Figure 4.51: Raster and raster inte
Page 69 and 70: ST_Present and ST_Passes predicates
Page 71 and 72: Chapter 5 User Guide Sometimes stor
Page 73 and 74: SELECT rast As origin, ST_Resample(
Page 75 and 76: • gvSIG plugin • MapServer thro
Page 77 and 78: SELECT ST_AsJPEG(rast) As rastjpg F
Page 79 and 80: FROM buff_temp GROUP BY id ORDER BY
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Chapter 6 Application Most of GIS a
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6.2 Tools Figure 6.3: PostGIS conne
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Figure 6.6: Band area. controlled b
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Figure 6.10: The loading map parall
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Figure 6.14: Maps representing worl
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Figure 6.17: Maps with a color lege
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their levels of awareness of geogra
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[15] Jorge Arevalo. PostGIS Raster
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Appendix A PostGIS Raster Utilisati
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eturn "Version 0.1" def qgisMinimum
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Appendix C Code Implementation C.1
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name="" # Setting table name and mo
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Figure D.1: Synthetic aperture rada
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D.4 Digital Image Processing D.4.1
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Figure D.4: Age of the sea floor. M
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Appendix F Continuous Surfaces One
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