Package com.luciad.format.raster

Class TLcdETOPOModelDecoder

java.lang.Object
com.luciad.format.raster.TLcdETOPOModelDecoder
All Implemented Interfaces:
ILcdInputStreamFactoryCapable, ILcdModelDecoder
@LcdService(service=ILcdModelDecoder.class, priority=20000) public class TLcdETOPOModelDecoder extends Object implements ILcdModelDecoder, ILcdInputStreamFactoryCapable
This model decoder decodes the raw ETOPO1, ETOPO2, ETOPO2v2, and ETOPO5 data sets. These data sets contain bathymetric and topographic rasters for the entire world, at 1-minute, 2-minute, and 5-minute resolutions, respectively. They can be downloaded from the National Geophysical Data Center (NGDC) at their Global Relief pages.

Input files

File Required Entry point Description
etopo1_ice_c_i2.bin
etopo1_bed_c_i2.bin		 x x Global Gridded 1-minute Database
ETOPO2v2c_i2_MSB.bin
ETOPO2v2_MSB.raw
ETOPO2.raw.bin		 x x Global Gridded 2-minute Database
ETOPO5.DAT x Global Gridded 5-minute Database

Supported file transfer protocols

  • This model decoder supports all transfer protocols that are supported by the inputStreamFactory of this decoder.

Model reference

The model reference is WGS84 with a EGM96 geoid datum.

Geoid support

The elevation values in the ETOPO data sets are measured as elevation above mean sea level (AMSL). This means that the elevations are offsets with respect to the geoid, the equipotential surface that coincides the mean ocean surface of the Earth.
By default, the TLcdETOPOModelDecoder decodes the data as AMSL, but it can be configured to not apply the geoid and instead interpret the data as above ellipsoid. This can be done for performance reasons since integrating geoid offsets can consume a considerable amount of memory and CPU time.
Geoid offsets can be supported in two ways:
  • Apply geoid datums: This setting will cause the decoder to return a model with the ellipsoid as vertical datum, but the returned data will have the geoid offsets incorporated. In other words, elevations are returned as above ellipsoid, but have been corrected with the geoid offset.
  • Support geoid datums: This setting will cause the decoder to return a model with the EGM-96 geoid model as vertical datum. If set to true, Elevation data is returned as above mean sea level.

Model structure

  • This model decoder creates a model per ETOPO file.
  • All models returned by this model decoder implement ILcd2DBoundsIndexedModel.

Model descriptor

  • All models returned by this model decoder have a TLcdETOPOModelDescriptor.
  • The type name of the model descriptor is the display name of this decoder.

Model elements

  • Each decoded model contains one object: an ALcdImage (and ILcdRaster) instance.
  • Decoded grid-centered data is always point-sampled. This is however only exposed via the ALcdImage interface. Legacy rasters are assumed to be area-sampled.

Useful settings

  • The property colorModel allows to override the default 16-bits index color that is attached to the decoded rasters, since ETOPO files don't contain any color information.

Sample code


 TLcdETOPOModelDecoder decoder    = new TLcdETOPOModelDecoder();
 ILcdColorModelFactory factory    = new TLcdDTEDColorModelFactory();
 ColorModel            colorModel = factory.createColorModel();

 decoder.setColorModel(colorModel);

 ILcdModel model = decoder.decode("etopo1_ice_c_i2.bin");

Performance tips

  • Since ETOPO rasters only provide a single level of detail, precomputing and storing multiple levels of detail may speed up visualization and some computations. For instance, the TLcdGeoTIFFModelEncoder can create compressed multilevel GeoTIFF files that can replace the original ETOPO files.

Thread safety

  • The decoding of models is thread-safe, as long as no properties are changed during the decoding.
  • The decoded models and elements are thread-safe for read access, on the condition that a thread-safe buffer is used.

Supported versions and specifications

  • [ETOPO1] Amante, C. and B. W. Eakins, ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and Analysis. NOAA Technical Memorandum NESDIS NGDC-24, 19 pp, March 2009.
  • [ETOPO2] ETOPO2v2 Global Gridded 2-minute Database, National Geophysical Data Center, National Oceanic and Atmospheric Administration, U.S. Dept. of Commerce, 2006.
  • [ETOPO5] ETOPO5 Global Gridded 5-minute Database, National Geophysical Data Center, National Oceanic and Atmospheric Administration, U.S. Dept. of Commerce, 1993-2005.

Known limitations

  • Only the big endian 2-byte integer (i2_MSB) databases are supported.
Since:
6.2

  • Field Details

    • DEFAULT_DISPLAY_NAME

      public static final String DEFAULT_DISPLAY_NAME
      The display name of this decoder.
      See Also:

    • ETOPO1_ICE_C_NAME

      public static final String ETOPO1_ICE_C_NAME
      The ETOPO1 cell-registered (with ice surface) file name.
      See Also:

    • ETOPO1_BED_C_NAME

      public static final String ETOPO1_BED_C_NAME
      The ETOPO1 cell-registered (with bedrock surface underneath ice) file name.
      See Also:

    • ETOPO1_ICE_G_NAME

      public static final String ETOPO1_ICE_G_NAME
      The ETOPO1 grid-registered (with ice surface) file name.
      See Also:

    • ETOPO1_BED_G_NAME

      public static final String ETOPO1_BED_G_NAME
      The ETOPO1 grid-registered (with bedrock surface underneath ice) file name.
      See Also:

    • ETOPO2v2c_NAME

      public static final String ETOPO2v2c_NAME
      The ETOPO2 version 2 (cell-registered, MSB) file name.
      See Also:

    • ETOPO2v2g_NAME

      public static final String ETOPO2v2g_NAME
      The ETOPO2 version 2 (grid-registered, MSB) file name.
      See Also:

    • ETOPO2v2_NAME

      public static final String ETOPO2v2_NAME
      The ETOPO2 version 2 (MSB) file name.
      See Also:

    • ETOPO2_NAME

      public static final String ETOPO2_NAME
      The ETOPO2 file name.
      See Also:

    • ETOPO5_NAME

      public static final String ETOPO5_NAME
      The ETOPO5 file name.
      See Also:

  • Constructor Details

    • TLcdETOPOModelDecoder

      public TLcdETOPOModelDecoder()
      Creates a new TLcdETOPOModelDecoder with a globally shared buffer for caching tiles.
      See Also:

    • TLcdETOPOModelDecoder

      public TLcdETOPOModelDecoder(ILcdBuffer aBuffer)
      Creates a new TLcdETOPOModelDecoder with the given shared buffer.

  • Method Details

    • setInputStreamFactory

      public void setInputStreamFactory(ILcdInputStreamFactory aInputStreamFactory)
      Sets the input stream factory that will be used for creating input streams given source names.
      Specified by:
      setInputStreamFactory in interface ILcdInputStreamFactoryCapable
      Parameters:
      aInputStreamFactory - the input stream factory to be used.

    • getInputStreamFactory

      public ILcdInputStreamFactory getInputStreamFactory()
      Returns the input stream factory that is used for creating input streams given source names.
      Specified by:
      getInputStreamFactory in interface ILcdInputStreamFactoryCapable
      Returns:
      the input stream factory that is used.

    • setColorModel

      public void setColorModel(ColorModel aColorModel)
      Sets the color model that is attached to decoded rasters.
      Parameters:
      aColorModel - a 16-bit IndexColorModel.

    • getColorModel

      public ColorModel getColorModel()
      Returns the color model that is attached to decoded rasters.

    • setSupportGeoidDatums

      public void setSupportGeoidDatums(boolean aSupportGeoidDatums)
      Specifies whether the decoded geodetic datum of the geodetic reference should be a geoid datum (EGM96), instead of the default ellipsoid datum (WGS84). The geoid varies smoothly between -110m and +90m around the ellipsoid. The geoid datum is more accurate, but it requires more memory and more processing time when it is being used in transformation calculations.

      More information on elevation handling can be found in the geoid section of the class documentation.

    • isSupportGeoidDatums

      public boolean isSupportGeoidDatums()
      Determines if geoid datum is supported or not. The default value is true.
      Returns:
      true if geoid datum is supported; false otherwise
      See Also:

    • setApplyGeoidDatums

      public void setApplyGeoidDatums(boolean aApplyGeoidDatums)
      Specifies whether the geoid heights of the geodetic datum (EGM96) should be added to the elevation data right away while decoding. The geoid varies smoothly between -110m and +90m around the ellipsoid. The geodetic datum of the geodetic reference will then be be an ordinary ellipsoid datum (WGS84). Decoded rasters will be more accurate, but the operation requires more memory and more processing time while decoding the elevation data (which is still done lazily).

      This is an alternative to setSupportGeoidDatums(boolean). It has precedence if both options are set.

      Note that the 0m elevation (sea level) becomes the geoid height, which may be confusing when a raster is displayed with an elevation color model that assigns blue colors to negative elevations.

      More information on elevation handling can be found in the geoid section of the class documentation

    • isApplyGeoidDatums

      public boolean isApplyGeoidDatums()
      Determines if geoid datum correction is applied during decoding or not.
      Returns:
      true if geoid datum correction is applied during decoding; false otherwise
      See Also:

    • getDisplayName

      public String getDisplayName()
      Description copied from interface: ILcdModelDecoder
      Returns a short, displayable name for the format that is decoded by this ILcdModelDecoder.
      Specified by:
      getDisplayName in interface ILcdModelDecoder
      Returns:
      the displayable name of this ILcdModelDecoder.

    • canDecodeSource

      public boolean canDecodeSource(String aSourceName)
      Description copied from interface: ILcdModelDecoder
      Checks whether this model decoder can decode the specified data source. It is acceptable for this method to return true for a source name while decode throws an exception for that same source name.

      For performance reasons, we strongly recommend that this will only be a simple test. For example: check the file extension of a file, but not that the file exists or contains expected content.

      Specified by:
      canDecodeSource in interface ILcdModelDecoder
      Parameters:
      aSourceName - the data source to be verified; typically a file name or a URL.
      Returns:
      true if the given source name is "etopo1_ice_c_i2.bin", "etopo1_bed_c_i2.bin", "ETOPO2v2c_i2_MSB.bin", "ETOPO2v2_MSB.raw", "ETOPO2.raw.bin", or "ETOPO5.DAT".
      See Also:

    • decode

      public ILcdModel decode(String aSourceName) throws IOException
      Description copied from interface: ILcdModelDecoder
      Creates a new model from the given data source.
      Specified by:
      decode in interface ILcdModelDecoder
      Parameters:
      aSourceName - the data source to be decoded; typically a file name or a URL.
      Returns:
      A model containing the decoded data. While null is allowed, implementors are advised to throw an error instead.
      Throws:
      IOException - for any exceptions caused by IO problems or invalid data. Since decoding invalid data almost always results in RunTimeExceptions (NullPointerException, IndexOutOfBoundsException, IllegalArgumentException, ...) on unexpected places, implementations are advised to catch RuntimeExceptions in their decode() method, and wrap them into an IOException, as illustrated in the code snippet below. 
      
   public ILcdModel decode( String aSourceName ) throws IOException {
      try (InputStream input = fInputStreamFactory.createInputStream(aSourceName)) {
         // Perform decoding ...
      } catch (RuntimeException e) {
         throw new IOException(e);
      }
   }
      See Also: