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Raster datasets and raster catalogs in a geodatabase stored in Oracle

Raster datasets and raster catalogs in a geodatabase stored in Oracle

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Raster data is spatial data represented in an array of equally sized cells arranged in rows and columns. Raster data can be made up of one or more raster bands. For a complete explanantion of raster data and its attributes, see the "Understanding raster data" book in this help. You can start with What is raster data?

Rasters in ArcCatalog

In ArcGIS, raster data can be stored in a single raster dataset or a raster catalog. A raster catalog is a group of raster datasets. For a description of these two types of storage, see Raster data organization.

In the ArcCatalog tree, individual raster datasets look like the following:

Raster dataset in ArcCatalog

If you expand the raster dataset, you will see the raster bands of which it is comprised.

Raster dataset showing bands

A raster catalog in the ArcCatalog tree would appear as follows:

Raster catalog in ArcCatalog

Raster tables in an Oracle DBMS

ArcSDE geodatabases in an Oracle DBMS store raster data in either LONG RAW, BLOB, or GeoRaster storage types.

For rasters stored in Oracle, a raster column is added to a business table, and each cell of the raster column contains a reference to a raster stored in a separate raster table. Therefore, each row of a business table references an entire raster.

When you import a raster into an ArcSDE geodatabase in Oracle, a raster column is added to the business table of your choice. You may name the raster column whatever you like, so long as it conforms to Oracle's column naming convention. ArcSDE restricts one raster column per business table.

A raster dataset stored in LONG RAW or BLOB is made up of seven tables in the geodatabase: the business table, feature table, spatial index table, auxiliary, block, band, and raster attribute tables. The following are the business and raster tables for a raster dataset called WORLD_TIF.

NOTE: Beginning with Oracle 11g, LONG RAW data types are no longer supported. Therefore, ESRI recommends you do not create new raster datasets using LONG RAW storage.

Rasters in an XML document

The following is a small portion of the content of an XML document for the World raster dataset. The first section is the header; subsequent lines define the dataset.

<esri:Workspace xmlns:esri="http://www.esri.com/schemas/ArcGIS/9.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <WorkspaceDefinition xsi:type="esri:WorkspaceDefinition">
   <WorkspaceType>esriRemoteDatabaseWorkspace</WorkspaceType> 
   <Version>sde.DEFAULT</Version> 
   <Domains xsi:type="esri:ArrayOfDomain" /> 
   <DatasetDefinitions xsi:type="esri:ArrayOfDataElement">
     <DataElement xsi:type="esri:DERasterDataset">
       <CatalogPath>/V=sde.DEFAULT/RD=GDB.world_TIF</CatalogPath> 
       <Name>GDB.world_TIF</Name> 
       <Children xsi:type="esri:ArrayOfDataElement">
          <DataElement xsi:type="esri:DERasterBand">
            <CatalogPath>/V=sde.DEFAULT/RD=GDB.world_TIF/RB=Band_1</CatalogPath> 
            <Name>Band_1</Name> 
            <DatasetType>esriDTRasterBand</DatasetType> 
            <DSID>-1</DSID> 
            <Versioned>false</Versioned> 
            <CanVersion>false</CanVersion> 
            <HasOID>true</HasOID> 
            <OIDFieldName>ObjectID</OIDFieldName> 
            <Fields xsi:type="esri:Fields">
              <FieldArray xsi:type="esri:ArrayOfField">
                <Field xsi:type="esri:Field">
                    <Name>ObjectID</Name> 
                    <Type>esriFieldTypeOID</Type> 
                    <IsNullable>false</IsNullable> 
                    <Length>4</Length> 
                    <Precision>0</Precision> 
                    <Scale>0</Scale> 
                    <Required>true</Required> 
                    <Editable>false</Editable> 
                </Field>
                <Field xsi:type="esri:Field">
                    <Name>Value</Name> 
                    <Type>esriFieldTypeInteger</Type> 
                    <IsNullable>true</IsNullable> 
                    <Length>0</Length> 
                    <Precision>0</Precision> 
                    <Scale>0</Scale> 
               </Field>
               <Field xsi:type="esri:Field">
                    <Name>Count</Name> 
                    <Type>esriFieldTypeInteger</Type> 
                    <IsNullable>true</IsNullable> 
                    <Length>0</Length> 
                    <Precision>0</Precision> 
                    <Scale>0</Scale> 
               </Field>
             </FieldArray>
         </Fields>
         <Indexes xsi:type="esri:Indexes">
           <IndexArray xsi:type="esri:ArrayOfIndex" /> 
         </Indexes>
         <IsInteger>true</IsInteger> 
         <MeanCellHeight>0.175996089009095</MeanCellHeight> 
         <MeanCellWidth>0.176000337991447</MeanCellWidth> 
         <Height>1024</Height> 
         <Width>2048</Width> 
         <PixelType>U8</PixelType> 
         <PrimaryField>1</PrimaryField> 
         <TableType>esriRasterTableValue</TableType> 
         <Extent xsi:type="esri:EnvelopeN">
            <XMin>-179.906382261841</XMin> 
            <YMin>-90.1303147686327</YMin> 
            <XMax>180.542309944643</XMax> 
            <YMax>90.089680376681</YMax> 
            <SpatialReference xsi:type="esri:GeographicCoordinateSystem">
   <WKT>GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]</WKT> 
          <XOrigin>-400</XOrigin> 
          <YOrigin>-400</YOrigin> 
          <XYScale>11258999068426.2</XYScale> 
          <ZOrigin>0</ZOrigin> 
          <ZScale>1</ZScale> 
          <MOrigin>0</MOrigin> 
          <MScale>1</MScale> 
          <XYTolerance>8.98315284119521E-09</XYTolerance> 
          <ZTolerance>2</ZTolerance> 
          <MTolerance>2</MTolerance> 
          <HighPrecision>true</HighPrecision> 
          <LeftLongitude>-180</LeftLongitude> 
         </SpatialReference>
        </Extent>
      </Data>
    </DatasetData>
   </WorkspaceData>
</esri:Workspace>