File Header (Unsigned Integers)
Bytes 0 – 80 (0x0 – 0x50)
The first 80 bytes of the FIN file is
file header information
in an array of
unsigned integers.
There are 20 unsigned integers in this array.
Each unsigned integer is 32-bits.
In C/C++, we declare the array:
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unsigned int uivecHeader[ 20 ];
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When writing this array to file,
since each variable in the array is multi-byte,
write one variable at a time
to ensure proper byte ordering of each 32-bit
variable:
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for ( i = 0; i < 20; i++ )
WriteUIntMSBFIRST( uivecHeader[ i ], pFile );
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When reading the multi-byte variables from file,
read one variable at a time:
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for ( i = 0; i < 20; i++ )
uivecHeader[ i ] = ReadUIntMSBFIRST( pFile );
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This array of variables defines the following file settings:
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uivecHeader[ 0 ] =
uivecHeader[ 1 ] =
uivecHeader[ 2 ] =
uivecHeader[ 3 ] =
uivecHeader[ 4 ] =
uivecHeader[ 5 ] =
uivecHeader[ 6 ] =
uivecHeader[ 7 ] =
uivecHeader[ 8 ] =
uivecHeader[ 9 ] =
uivecHeader[ 10 ] =
uivecHeader[ 11 ] =
uivecHeader[ 12 ] =
uivecHeader[ 13 ] =
uivecHeader[ 14 ] =
uivecHeader[ 15 ] =
uivecHeader[ 16 ] =
uivecHeader[ 17 ] =
uivecHeader[ 18 ] =
uivecHeader[ 19 ] =
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File Signature
File Version
File Size High
File Size
Grid Width
Grid Height
Tile Width
Tile Height
Number of Matrices
Byte Flags
Ptr to Tile Addresses
Ptr to Block Addresses
Ptr to Band Addresses
Reserved
Ptr to File Dynamic Range
Ptr to File Bias
Ptr to Copyright Notice
Ptr to Text Titles
Ptr to Text Comments
Ptr to Custom Data
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File Signature (Magic Number)
Must be 0x46494e00
File Version
Must be 1
File Size High
0 = Default
If the file size is 64 bits, then this is the high order
32 bits of the file size.
If the file size is 32 bits,
then this is zero.
File Size
Size of the file (number of bytes).
If the file size is 64 bits,
this is the low order 32 bits of the file size.
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Grid Width and Height
Size of grid, in floating point numbers or integers.
The grid width is the number of columns in the grid.
The grid height is the number of rows in the grid.
Both of these variables
(Grid Width and Height) can be zero if only blocks are
used (without bands), and if both variables (not just one
of these variables) are zero, in which case the two variables can
be ignored (or determined by examining the blocks).
For example, you can store a file of vector polylines
with each polyline as a block without specifying grid extents.
Tile Width and Tile Height
Size of each tile.
Tile width is the number of columns in the tile.
Tile Height is the number of rows in the tile.
Both can be set to zero if tiling
will not be used, or if the file will be
a single tile and blocks and bands are not used.
Number of Matrices
This is how many channels (planes) of data are stored.
For example, if the file stores a matrix of longitude values
and a matrix of latitude values, the Number of Matrices is 2.
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Byte Flags
Bytes settings that are accessed with shifting.
Byte settings that are not used must be 0x00.
The following byte settings are always used:
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Compression =
Type of Grid Node =
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uivecHeader[ 9 ] & 255
( uivecHeader[ 9 ] >> 8 ) & 255
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Compression
0x00 if compression is turned OFF for the file, or
0x01 if compression is turned ON for the file.
Type of Grid Node
0x00 = ANSI/IEEE Floating Point
0x01 = Integer
0x02 = FloatBin
Type of uncompressed grid node.
All grid nodes of the file will be of this type
before any compression/encoding.
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If the Type of Grid Node is 0x00 or 0x01, then the
Size of Grid Node
is stored as:
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Size of Grid Node = ( uivecHeader[ 9 ] >> 8 ) & 255
Specifies the size in bytes of an
uncompressed grid node:
0x04 or 0x08 if the Grid Node Type is 0x00
(ANSI/IEEE floating point numbers);
at least 0x01 if Grid Node Type is 0x01
(integers);
can be 0x00 if Grid Node Type is 0x00
(then 0x08 is assumed as the Grid Node Size).
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If the Type of Grid Node is 0x02, then
each uncompressed grid node is 18 bytes
(see the
FloatBin
specification)
and the Size of Grid Node should be zero.
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