vil_nitf2_image_subheader.h

Go to the documentation of this file.

// vil_nitf2: Written by Rob Radtke (rob@) and Harry Voorhees (hlv@) of
// Stellar Science Ltd. Co. (stellarscience.com) for
// Air Force Research Laboratory, 2005.
#ifndef VIL_NITF2_IMAGE_SUBHEADER_H
#define VIL_NITF2_IMAGE_SUBHEADER_H
//:
// \file

#include <vcl_vector.h>

#include "vil_nitf2_field_sequence.h"
#include "vil_nitf2_classification.h"
#include "vil_nitf2.h"

class vil_stream;
class vil_nitf2_data_mask_table;
//:
// This class is responsible for parsing a NITF 2.1 image header.
// It is used by vil_nitf_image for this purpose.  You can access
// any of the information in the header via the appropriate
// get_property() function.  There are also some shortcut
// functions for getting commonly needed data like nplanes()
// etc.
class vil_nitf2_image_subheader
{
 public:
  vil_nitf2_image_subheader( vil_nitf2_classification::file_version version );
  virtual ~vil_nitf2_image_subheader();

  //: Read the image header starting at stream's current position.
  // \returns false if failed
  virtual bool read( vil_stream* stream );
  //virtual bool write( vil_stream* stream );

  //: Sets \a out_value to the value of field specified by tag.
  // \returns 0 if such a field is not found or is of the wrong type.
  template< class T >
  bool get_property(vcl_string tag, T& out_value) const
  {
    return m_field_sequence.get_value( tag, out_value );
  }

  //: Sets out_value to the value of vcl_vector field element specified by tag and index.
  // \returns 0 if such a field is not found or is of the wrong type.
  template< class T >
  bool get_property(vcl_string tag, int i, T& out_value) const
  {
    return m_field_sequence.get_value( tag, i, out_value );
  }

  unsigned int nplanes() const;
  unsigned int get_pixels_per_block_x() const;
  unsigned int get_pixels_per_block_y() const;
  unsigned int get_num_blocks_x() const;
  unsigned int get_num_blocks_y() const;
  bool has_data_mask_table() const { return data_mask_table() != 0; }
  const vil_nitf2_data_mask_table* data_mask_table() const { return m_data_mask_table; }

  //:
  // Returns true if the ith image band in this image subheader has LUT info
  // and false otherwise.  If it returns true, then all the out parameters
  // will be populated from the header data.
  // \param n_luts: number of luts for this image band (NITF spec says
  //                it's in the range [1-4] (if luts present)
  // \param ne_lut: number of elements in each lut
  // \param lut_d: the LUT data indexed first by lut, then lut element
  //               ie, the last element would be lut_d[n_luts-1][ne_lut-1]
  //
  // See the NITF spec for exactly how this data is to be interpretted.  Here's
  // a summary:
  // LUTS always contain 8 bit unsigned data.  If n_luts is 1, then this band
  // is to be transformed into an 8-bit image plane.  Each pixel value in the
  // original image can be used as an index into lut_d.  (ie. lut_d[0][pixelVal])
  // If n_luts is 2, then the output image plate will be 16 bits.  The MSBs of
  // each of the output pixels will be obtained from lut_d[0] and the LSBs will
  // be obtained from lut_d[1].
  // If n_luts is 3, then this plane will be transformed into 3 planes: R, G and B.
  // lut_d[0] shall map to Red, lut_d[1] shall map to Green, and lut_d[2] shall map
  // to Blue.
  bool get_lut_info( unsigned int band, int& n_luts, int& ne_lut,
                     vcl_vector< vcl_vector< unsigned char > >& lut_d ) const;

  // I allocate the return value, but you own it after I return it to you
  // so you need to delete it.
  virtual vil_nitf2_field::field_tree* get_tree( int i = 0 ) const;

  //
  //: Get RPC parameters, if present. User provides rpc_data array.
  // The parameters describe a camera projection based on the 
  // ratio of cubic polynomials in (lon, lat, ele). All variables
  // are normalized to the range [-1, 1] using scale and offset parameters.
  // For further definition of parameters see 
  // http://www.ismc.nima.mil/ntb/superceded/vimas/vimas.pdf 
  // The returned rpc_data vector is encoded as:
  //  rpc_data[0]-rpc_data[19]         Line Numerator Cubic Coefficients
  //  rpc_data[20]-rpc_data[39]        Line Denominator Cubic Coefficients
  //  rpc_data[40]-rpc_data[59]        Sample Numerator Cubic Coefficients
  //  rpc_data[60]-rpc_data[79]        Sample Denominator Cubic Coefficients
  //  rpc_data[80] Line Offset         rpc_data[81] Sample Offset     
  //  rpc_data[82] Latitude Offset     rpc_data[83] Longitude Offset     
  //  rpc_data[84] Elevation Offset    rpc_data[85] Line Scale
  //  rpc_data[86] Sample Scale        rpc_data[87] Latitude Scale
  //  rpc_data[88] Longitude Scale     rpc_data[89] Elevation Scale     
  //
  //  The ordering of coefficients can vary as indicated by rpc_type
  //  Defined extensions are RPC00A and RPC00B.
  bool get_rpc_params( vcl_string& rpc_type, vcl_string& image_id, 
                       vcl_string& image_corner_geo_locations,
                       double* rpc_data );

 protected:
  vil_nitf2_field_sequence m_field_sequence;
  vil_nitf2_data_mask_table* m_data_mask_table;

  vil_nitf2_classification::file_version m_version;

  static const vil_nitf2_field_definitions* get_field_definitions_21();
  static const vil_nitf2_field_definitions* get_field_definitions_20();

 private:
  static void add_shared_field_defs_1( vil_nitf2_field_definitions* defs );
  static void add_shared_field_defs_2( vil_nitf2_field_definitions* defs );
  static void add_geo_field_defs( vil_nitf2_field_definitions* defs, const vil_nitf2_classification::file_version& version );
  static void add_shared_field_defs_3( vil_nitf2_field_definitions* defs );
  static void add_rpc_definitions();
  static vil_nitf2_field_definitions* s_field_definitions_21;
  static vil_nitf2_field_definitions* s_field_definitions_20;
  // so these static members can be cleaned up when the program is done
  // using nitf files
  friend void vil_nitf2::cleanup_static_members();
};

#endif // VIL_NITF2_IMAGE_SUBHEADER_H

---