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

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Chapter 3 Why PostGIS Raster ? ORACLE GEORaster is a component that supports continuous fields in ORACLE. Nevertheless, it sounds complex and cumbersome for inexperienced users. PostGIS Raster is thus designed to overcome these limitations. This fact will be demonstrated through PostGIS Raster goals and how Oracle GeoRaster and PostGIS Raster are different in architecture, physical storage, indexing and overlapping, along with some principal operations when working with raster data. 3.1 Goals PostGIS Raster, an extension of PostGIS, implements a new raster data type that adapts to diversity of applications by achieving four objectives [6]: 3.1.1 Simplicity and Complementarity Seen a raster type is designed to adapt to diversity of applications, then the first objective of PostGIS Raster is to provide a simple loader to import rasters into database. The loader allows users to load a single raster or a set of rasters once. This new data type complements the existing PostGIS vector type in the sense that it works in the same way as the one of vector type, but instead of association with geometric elements, raster relates to a matricial data structure. 3.1.2 Transparent Integration with Vector PostGIS Raster provides a set of similar operators and functions with those available for vector type to support raster. In this way, users can use their knowledge about vector type to expect similar behaviors when using these operator and functions. Thus it enhances user’s interaction with geospatial applications. About developers, a single SQL paradigm for both raster and vector types will help them write better GIS applications. Developers will build a unique graphical user interface for both raster and vector data. 3.1.3 Storage Flexibility In addition to traditional storage (in-database storage), PostGIS Raster allows user to simply register only metadata of raster images stored in the filesystem (out-database storage). When retrieving these out-database rasters from database, they are accessed directly from the filesystem. 3.1.4 Interoperability PostGIS Raster uses Geospatial Data Abstraction Library (GDAL) [25] to load rasters into the database and to work with out-database rasters. With GDAL, PostGIS Raster can work with nearly a hundred file formats 1 ). 1 http://www.gdal.org/formats_list.html. 19
These additional functionalities make PostGIS Raster more than just a new raster format but also a necessary complement to PostGIS. 3.2 PostGIS Raster Versus ORACLE GEORaster 3.2.1 Architecture General Architecture In general, tools supporting raster data include five components [3]: Characteristics Oracle GeoRASTER PostGIS Raster SQL API Standard SQL A single set of SQL functions for vector and raster data Accessing to Java, Oracle Call Interface (OCI), Oracle C++ Call PostGIS SQL API raster data Interface (OCCI), and GeoRaster SQL API Viewing tools Oracle Fusion Middleware MapViewer, Open- QGIS and gvGIS Import/Export data JUMP Extract, transform and load (ETL) GDAL allows loading a single raster or a set of Data formats Six standard image formats: GeoTIFF, DEM, PNG, BMP, GIF, and JPEG Data Architecture rasters As many image formats as GDAL does [21] In Oracle GeoRASTER, each image is stored as a single object of type SDO_GEORASTER. A GeoRaster table is a table which has at least one data column of type SDO_GEORASTER. SDO_GEORASTER objects include metadata and information about how to retrieve GeoRaster data which is stored in another table, called a Raster Data Table (RDT). GeoRaster data is an object of type SDO_RASTER which includes a Binary Larger Object (BLOB) column called RASTERBLOCK storing the raster blocks (The core of raster data can be partioned into small blocks for optimal storage and retrieval). A block is also called a tile [3]. Figure 3.1: GeoRaster data architecture [3]. Other information associated with the GeoRaster objects can be stored in separate columns or tables, such as a Value Attribute Table (VAT). More simply, PostGIS Raster uses only one type raster to store a raster image. Like the geometry type, the raster type is a complex type, embedding information about raster itself with its georeference. In PostGIS Raster, there is no table for storing the raster data (like Oracle Spatial SDO_RASTER) and another table for storing the georeference and the metadata (like Oracle Spatial SDO_GEORASTER). 20
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: 2.6.3 Traditional Knowledge GIS Tra
Page 31 and 32: Figure 3.3: Physical storage of Geo
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
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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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PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

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