GeoRaster Overview and Concepts

GeoRaster is a feature of Oracle Spatial that lets you store, index, query, analyze, and deliver raster image and gridded data and its associated metadata.

GeoRaster provides Oracle Spatial data types and an object-relational schema. You can use these data types and schema objects to store multidimensional grid layers and digital images that can be referenced to positions on the Earth’s surface or in a local coordinate system. If the data is georeferenced, you can find the location on Earth for a cell in an image; or given a location on Earth, you can find the cell in an image associated with that location.

GeoRaster can be used with data from any technology that captures or generates images, such as remote sensing, photogrammetry, and thematic mapping. It can be used in a wide variety of application areas, including location based services, geoimagery archiving, environmental monitoring and assessment, geological engineering and exploration, natural resource management, defense, emergency response, telecommunications, transportation, urban planning, and homeland security.

Note:

• To use GeoRaster, you must understand the main concepts, data types, techniques, operators, procedures, and functions of Oracle Spatial, which are documented in Oracle Spatial Developer’s Guide.

• You should also be familiar with raster and image concepts and terminology, techniques for capturing or creating raster data, and techniques for processing raster data.

• By default, the GeoRaster feature is disabled after Oracle Spatial is initially installed, and it must be enabled for each schema that will use GeoRaster. In order to enable GeoRaster, the schema must have the CREATE TRIGGER privilege. See Enabling GeoRaster at the Schema Level for information and instructions.

This chapter describes the core concepts and features of GeoRaster, including the GeoRaster data model and storage schema, georeferencing models, metadata support, resampling algorithms, pyramids, compression, parallel processing, loading and exporting capabilities, and the Java API. It contains the following major sections.

• Vector and Raster Data
  Geographic features can be represented in vector or raster format, or both.

• Raster Data Sources
  Raster data is collected and used by a variety of geographic information technologies, including remote sensing, airborne photogrammetry, cartography, and global positioning systems.

• GeoRaster Data Model
  Raster data can have some or all of the following elements.

• GeoRaster Physical Storage
  GeoRaster optimizes the physical storage of metadata and data.

• Bands, Layers, and Metadata
  In GeoRaster, band and layer are different concepts.

• Georeferencing
  The GeoRaster spatial reference system (SRS), a metadata component of the GeoRaster object, includes information related to georeferencing. Georeferencing establishes the relationship between cell coordinates of GeoRaster data and real-world ground coordinates (or some local coordinates). Georeferencing assigns ground coordinates to cell coordinates, and cell coordinates to ground coordinates.

• Resampling and Interpolation
  Many image and raster transformations and operations involve pixel or cell resampling and interpolation.

• Pyramids
  Pyramids are subobjects of a GeoRaster object that represent the raster image or raster data at differing sizes and degrees of resolution.

• Bitmap Masks
  A bitmap mask is a special one-bit deep rectangular raster grid with each pixel having either the value of 0 or 1. It is used to define an irregularly shaped region inside another image. The 1-bits define the interior of the region, and the 0-bits define the exterior of the region.

• NODATA Values and Value Ranges
  A NODATA value is used for cells whose values are either not known or meaningless.

• Compression and Decompression
  GeoRaster provides the following types of native compression to reduce storage space requirements for GeoRaster objects: JPEG (JPEG-F), JPEG 2000, and DEFLATE.

• GeoRaster and Database Management
  GeoRaster enables you to perform database management tasks.

• Parallel Processing in GeoRaster
  There are two types of parallel processing with GeoRaster.

• Reporting Operation Progress in GeoRaster
  For some resource-intensive operations, GeoRaster enables you to monitor and report their execution progress.

• Raster Tiles

• GeoRaster PL/SQL API
  GeoRaster provides the SDO_GEOR, SDO_GEOR_ADMIN, SDO_GEOR_AGGR, SDO_GEOR_RA, and SDO_GEOR_UTL PL/SQL packages, which contain subprograms (functions and procedures) to work with GeoRaster data and metadata.

• GeoRaster Java API
  The Oracle Spatial GeoRaster Java API consists of interfaces and classes that support features available with the GeoRaster feature of Oracle Spatial.

• GeoRaster REST API
  The GeoRaster REST API consists of a set of endpoints that enable users to access GeoRaster data and GeoRaster features through web clients.

• GeoRaster and Python
  You can work with GeoRaster database using the python-oracledb Python extension module.

• GeoRaster Spatial Web Services
  A web service enables developers of Oracle Spatial GeoRaster applications to provide raster data and metadata to their application users over the web. GeoRaster supports Open Geospatial Consortium (OGC) web services, specifically, Web Coverage Services (WCS) and Web Map Services (WMS).

• GeoRaster Support in Spatial Studio and Map Visualization Component
  You can work with GeoRaster data in both Oracle Spatial Studio and Spatial Map Visualization Component.

• GeoRaster Tools: Viewer, Loader, Exporter
  Oracle Spatial includes tools for viewing, loading, and exporting GeoRaster data.

• GeoRaster PL/SQL, Java, and Python Sample Files
  GeoRaster includes several PL/SQL, Java, and Python sample code files that show common operations.

• README File for Spatial and Related Features
  Oracle Spatial includes a README.txt file.