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

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(x,y), where x refers to the distance along the horizontal axis and y refers to the distance along the vertical axis. The origin is defined as (0,0). For example, in Figure 2.19, the notation (4, 3) gives a point that is four units over in x and three units up in y from the origin. Figure 2.19: 2D Cartesian coordinate system. [26]. 3D Cartesian coordinate system is a coordinate system that uses also a z value to measure elevation above or below sea level. The notation (2, 3, 4) in Figure 2.20 records a point that is two units over in x and three units in y from the origin and whose elevation is 4 units above the Earth’s surface such as 4 meters above sea level. Figure 2.20: 3D Cartesian coordinate system [26]. Since the Earth is spherical, a challenge faced by cartographers is how to represent the real world using a flat coordinate system. The process of flattening the Earth is called projection, hence the term map projection is resulted. Examples of various methods for map projection are illustrated in Figure 2.21. Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles and areas across the two dimensions. However, all map projections representing the Earth’s surface create distortions in some aspect of distance, area, shape, scale or direction (Figure 2.22). Depend on user application, many map projections are designed for specific purposes. One map projection might be used for preserving shape while another might be used for preserving the area. These properties of the map projection are important parameters in the definition of the coordinate system for each GIS dataset and each map. With these properties, the geographic locations of dataset elements can be reprojected and transformed into an appropriate coordinate system. As a result, it’s possible to integrate and combine information from multiple GIS layers. This is a fundamental GIS capability as accurate location forms the basis for almost all GIS operations. 15
2.6 GIS Applications 2.6.1 Crime Mapping Figure 2.21: Different methods for map projection [26]. Figure 2.22: Distorsion in map projection [26]. Crime mapping is an application used by analysts in law enforcement agencies to map, visualize and analyse crime incident. Using Geographic Information Systems, crime analysts can overlay different datasets (such as census demographics, locations of pawn shops, schools and etc.) to identify crime hot spots, to better understand the underlying causes of crime and thus to devise strategies dealing with the problem, along with other trends and patterns [18]. 2.6.2 GIS and Hydrogeology Nowadays, with increasing demand on surface water resources and 98% of the world’s available fresh water is groundwater, it implies that the demand for groundwater will also increase. In fact, in some places, this resource has already been seriously exploited and even mismanaged (Figure 2.24). Hence, more knowledge about its disposition is quickly required. Hydrogeology, a subset of hydrology, is concerned with the way in which groundwater is stored and its availability for use. Not as apparent as surface water flows, the description of groundwater is a more complex task than that of surface water. Groundwater is water located under the Earth’s surface. Groundwater moves much more slowly than surface water and is 3-dimensional flow (2-dimensional in the case of surface water flow). Groundwater flow is a function of geology and head. That means it flows from higher head to lower head and its flow path can be predicted by geology. Head values, geology and groundwater flow direction are the features which may be presented in GIS. Then hydrogeology is especially suited to GIS because groundwater can be characterized spatially in GIS and analyzed by scientists. For example, in a simple application of GIS, the effect of a new feature can be studied on the groundwater. The results of such study then can be used by decision makers to determine whether or not to proceed with drilling. 16
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: measures of latitude. Longitude mea
Page 27 and 28: 2.6.3 Traditional Knowledge GIS Tra
Page 29 and 30: These additional functionalities ma
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(
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• gvSIG plugin • MapServer thro
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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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