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RAMP AMM-1 SAR Image Mosaic of Antarctica:

README file for 25 m tiles


GENERAL INFORMATION AND DIRECTORY STRUCTURE
RAMS - 	Radarsat Antarctic Mapping System.  Software developed by the
	Vexcel Corporation to process the Radarsat image data.
Block- 	Blocks comprise ~150-200 frames that have been geocoded, terrain
	corrected, radiometrically balanced and mosaicked together. 
	See Block Processing Stage below for additional information.
Tile-  	Tiles are made up of Blocks that have undergone Block to Block 
	grand geometric and radiometric balancing. There are 93 tiles which
 	make up Antarctica.  See the section on TILE & SUB-TILE NAMING 
	CONVENTIONS for additional information.
Tile Products- are the Final RAMS Products that will be distributed to the
	community.  Final Tile Products can have a file size for 16-bit 
	image products up to 900Mb.  A final tile product contains 
	several layers of data:  
		SAR imagery,
		shadow/layover/incidence angle masks,
		digital elevation data, 
		imagery indices.  
	Some utility programs are also provided which may be useful 
	for interpreting the image data.  All of these things are 
	distributed in seven directories:
	ANGLES.DIR   - shadow / layover / incidence angle masks
	DEMINDEX.DIR - DEM index table and support files
	DEMS.DIR     - DEMs and DEM index values
	IMAGES.DIR   - SAR imagery indices
	IMGINDEX.DIR - SAR image index table and support files
	INDICES.DIR  - SAR imagery indices
	MASTER.TXT   - list of all sub-tiles in the tile
	PROGRAMS.DIR - utility programs
	README.TXT   - This document
Other data files:
	Tiles.nam    - Text file cross referencing database structure
		       with Tile Name ie: til_89  SP_20-20
					  til_90  SP_21-21
	tile_name.gif- Graphic showing tile distribution and tile names
	SS_00-00.gif - Graphic showing the image data contained in that
			specific tile.
SubTile-A subtile is a uniform raster binary image of a standard
	dimension (2048x2048 for 16-bit products) that make up a Tile.
	A tile could contain as many as 98 subtiles depending on the
	geometry/size of the Tile and the amount of data coverage contained
	in the tile. See the section on TILE & SUB-TILE NAMING CONVENTIONS
	for additional information
Final-	The term "Final" indicates that the SAR data are derived from
	blocks which have been individually processed then mosaicked 
	together in a step called the "Grand Adjustment". In general, 
	a block, which consists of a collection of contiguous frames, 
	is formed by the following processing steps:
PROCESSING STEPS
Block Processing Stage:
	SAR data ingest (level 1 products)
	Ground control points located
	Tie points collected between images
	Block adjustment (to correct relative and absolute errors in
		state vectors)
	Orthorectification (terrain distortion removal and, optionally,
		radiometric corrections for pixel size)
	Tie points collected between orthorectified images
	Radiometric balancing (for radiometric seam removal)
	Geometric warp (optional, for residual geometric seam removal)
	Block mosaic formation 
	Reset shadow / layover areas to no-data
	Mosaic fill-in with shadow / layover imagery
	Preliminary product formation (optional)
	Extraction of image chips around block boundaries for 
		block-to-block tie point computation in the Tile Processing
		Stage.
Tile Processing Stage:
	Grand Adjustment: done after all blocks in the mosaic have been
		processed.  The purpose of the adjustment is to remove
 		block-to-block geometric and radiometric seams. Seam 
		removal requires the computation of tie points from the 
		image chips extracted from each block. During this 
		process an optimal 16 to 8-bit look up table is also 
		computed if the final product is 8 bit.
	Final tiles are then produced from block data by applying the 
		seam removal and radiometric equations derived from the 
		block-to-block tie points.  If the output type is 8 bit, 
		the 16 to 8-bit look up table is also applied.

TILE & SUB-TILE NAMING CONVENTIONS
        For RAMS, each Tile roughly corresponds to an area delineated
by the boundaries of the International Map of the World 1:1,000,000 map
sheets for Antarctica.  The tile naming convention used is taken from
the same source.  (See also the Antarctic Digital Database documentation
from the British Antarctic Survey.)
        For other uses of this system, a tile is defined as any arbitrary
collection of sub-tiles in a given map projection and for a given area.
        The list of sub-tiles comprising a tile is given in the MASTER.TXT
file.  This file contains the list of sub-tile names and their minimum
and maximum corner x, y values in map coordinates (Polar Stereographic 
using a WGS84 ellipsoid).
        For all map products supported by this system, each sub-tile
follows the following naming convention:  Each sub-tile is the same size
(51.2 km on a side or 2048x2048 pixels) with four sub-tiles residing 
around the origin of the map projection.  The common corner is located 
at the South Pole (for RAMS) or (0,0).  From the origin to the right, 
the subtiles are named E001..., E002..., etc.  
>From the origin to the left, the subtiles are named W001..., W002..., etc.  
>From the origin to the top, the subtiles are named ...T001, ...T002, etc.  
>From the origin to the bottom, the subtiles are named ...B001, ...B002, etc.

FILE CONTENTS AND THEIR USE
"CD.C"  - This file contains utility functions used by the programs
	listed above.
"CD.H"  - The header file for CD.C.
"README.TXT"  -  this file
"MASTER.TXT"  -  This file contains a list of all sub-tiles in
	the tile (including each sub-tile name and corner coordinates). The
	pixel spacings for imagery, shadow / layover / incidence angle masks,
	DEMs, and index tiles are given.  Map projection information is also
	provided.  To look up the full name of the projection, see the file
	"PJ_LIST.H" in the PROGRAMS.DIR/PROJ.DIR directory.
"ANGLES.DIR/.SLI"  -  These are the shadow/layover/incidence 
	angle sub-tiles.  These are 8-bit unsigned integer binary raster 
	images.  Each sub-tile is of dimension 512 x 512 (100 meter pixel 
	spacings).  The encoding is as follows:
	0	: shadow region
	1..253	: incidence angle = 90 - < 8-BIT DATA NUMBER >
	254	: layover region
	255	: no-data
"DEMS.DIR/.DEM" - These are the DEM sub-tiles.  They are
	headerless, 16-bit unsigned integer binary raster images.  For 
	RAMS, each sub-tile is 256 x 256. -9999 signifies no-data values 
	for the 16-bit product.
"DEMINDEX.DIR/.DIN" - This directory contains text files 
	indexing the data source contributing to the construction of the
	DEM  ie: 0 = "ADD Contours & Elevation Points, ERS_1 Altimeter Ice Mode 
		     & Ocean Mode"
"IMAGES.DIR/.IMG"  -  These are the image sub-tiles.  
	They are headerless, 16-bit unsigned integer binary
	raster images.  For RAMS, each sub-tile is 2048 x 2048.  To convert 
	each DN value back to sigma0, use the program GETSIG0.C in the 		
	PROGRAMS.DIR directory. -9999 signifies no-data values for the 
	16-bit product.
"IMGINDEX.DIR" - This directory contains files documenting the
	processing history of the images.  The following files are included:
   "BLOCKS.KEY" contains a list of blocks contributing to the tile and 
  	the associated coefficients used to radiometrically  and geometrically
  	adjust the blocks. 
   "FRAMES.KEY" contains a list of frames contributing to the tile and
  	for each the associated GCP's, Ephemiris and  radiometric balancing 
  	coefficients.
   "INDEX.TBL"  -  This is the index table for the entire tile.  The 
	index table contains rows of entries.  The first column contains the
	index value.  The second column contains the Orbit and Frame numbers.

"INDICES.DIR/.IDX"  - These are the index sub-tiles.  They are 
	stored as 8-bit raster images of dimension 512 x 512 (100 meter pixel 
	spacings).  Each DN value corresponds to an entry in the index table
	found in the IMGINDEX.DIR/INDEX.TBL.
"PROGRAMS.DIR": The following C programs are provided for final tile products.
	All programs contain documentation on compiling and linking in their 
	headers. A Makefile is also provided to help users build and link the 
	programs properly.
    "GEO2MAP.C"  - This program converts latitude and longitude to
	x, y map coordinates.  The projection name and ellipsoid are read
	from the MASTER.TXT file.
	GEO2MAP -h
        GEO2MAP: To convert (lat,lon) to map (x,y)
        Usage:  GEO2MAP [,] 
        [-h]              - (help) print usage
        [-db]             - (debug) print detailed info
	example:GEO2MAP -67.56622 -68.11323
		-2289977.407354, 919950.84983  
        This program can be converted to a function.  Instructions for doing
	so are provided within the header comments.
    "MAP2GEO.C"  - This program converts x, y map coordinates to
	latitude, longitude.  The projection name and ellipsoid are read
	from the MASTER.TXT file.
        MAP2GEO -h
        MAP2GEO: To convert map (x,y) to (lat,lon)
        Usage:  MAP2GEO [,] 
        [-h]              - (help) print usage
        [-db]             - (debug) print detailed info
	example:MAP2GEO -2289977, 919950
			-67.56622, -68.11324
        This program can be converted to a function.  Instructions for doing
	so are provided within the header comments.
   "TILE2MAP.C"  - This program converts RAMS tile name, line (col), & sample 
	(row) to RAMS map x,y coordinates
	TILE2MAP -h
	usage: TILE2MAP 
          [-h]                    - (help) print usage
          [-db]                   - (debug) print detailed info
          [-l]              - default: 1st line in subtile
          [-s]            - default: 1st pixel in line
          [-p]  - default: 25 meters square
          [-t]  - default: 51200 meters square
	ie:	TILE2MAP W045T018 -l 50 -s 150
		map (x, y) = (-2300275.000000, 920375.000000)
    "MAP2TILE.C" - This programs gives the Subtile name, and column and
	row which a specified map x,y coordinate is contained.
	MAP2TILE -h
	
	Usage: MAP2TILE [,] 
          [-h]                    - (help) print usage
          [-db]                   - (debug) print additional info
          [-n]   - name convention to use
               default: T,B,E,W     (Top, Bottom, East, West)
          [-p]  - default: 25 meters square
          [-t]  - default: 51200 meters square
	MAP2TILE -1968800 -104000
	W039B003 line: 65, sample: 1121
    "MERGEMAP.C"  -This programs generates a mosaic of SAR image
	subtiles within an area specified by center point and size.  
	The mosaic includes entire subtiles so the output size may 
	be different from the size specified. The -hdr option will generate
	a header text file containing samples, lines (cols,rows) the upper 
	right and lower left x,y map coordinates. At this time only SAR 
	image subtiles can be merged using this routine. 
 Usage: MERGEMAP -l  -size  -path <...> -fout <...> -hdr [-h -db]
      Where:
          -l    - center point latitude and longitude
           -size    - dimensions of output image in meters
           -path <...>    - path to the base product directory
           -fout <...>    - path/name of the output image
           -h             - (help) print usage
           -hdr           - output header file (.h) for image
           -db            - debug info
    ie: MERGEMAP -l -67.5 -68.1 -size 150000 150000 -path ../ -fout FILE.OUT -hdr
     "GETSIG0.c"  - This program prints to standard out the "original"
	pixel value in power for a pixel at image location (x, y) in map 
	coordinates.  It inverts the geometric adjustment applied during block
	to block processing and	the radiometric balancing applied during both 
	block processing block to block processing and converts the 16-bit 
	value to power.  It does not invert any radiometric corrections made 
	during orthorectification due to terrain. There is also some
 	uncertainty in the inversion as the index tile used to determine 
	which pixels come from which images is provided at a lower 
	resolution than the imagery itself.  At this time sigma0 is calculated
	on a pixel by pixel basis.
 
	GETSIG0 -h
	GETSIG0: To obtain original sigma nought value at (x,y)
		 Usage: GETSIG0 [,] 
           	[-h]              - (help) print usage
           	[-db]             - (debug) print detailed info
	ie:  	GETSIG0 -2404300 1197000
		Sigma Nought (-2404300.000000, 1197000.000000): -21.211612
        This program can be converted to a function.  Instructions for doing
	so are provided within the header comments.
    "MAKEFILE"  - A Unix Makefile for the programs.  
	Make libproj first:  
	Go to the PROGRAMS.DIR/PROJ.DIR/ and type "make"
	Then build the individual programs:
	Go to the PROGRAMS.DIR/ and type "make -f MAKEFILE"
    "PROJ.DIR/*"  - This directory contains the map projection library
	source code used by RAMS.  The header file "PROJECTS.H" is included in
	"CD.H".  A "MAKEFILE" is provided to build the map projections library
	libproj.  The default compilation flags are -I. to indicate that 
	header files are stored locally.  If you wish to add any flags, set 
	the environment variable VX_DEFS to the desired additional flags.  If 
	you need to remove or modify any of the flags, modify the definition 
	of CFLAGS in the Makefile.  Note that the library must be linked with 
	the standard C math library (see LIBS in the Makefile).
GETTING STARTED:
1) The extracted Tile data from DVD will have the following directory
   structure:
        til_00/cd/ANGLES.DIR    (shadow/layover/incidence angle masks)
                  DEMINDEX.DIR  (DEM index table and support files)
                  DEMS.DIR      (DEMs and DEM index values)
                  IMAGES.DIR    (SAR imagery, 16-bit binary)
                  IMGINDEX.DIR  (SAR image index table and support files)
                  INDICES.DIR   (SAR imagery indices)
                  MASTER.TXT    (sub-tile name and corner coordinates)
                  PROGRAMS.DIR  (utility programs)
                  README.TXT
		  Tiles.nam    - Text file cross referencing database structure
		       		  with Tile Name ie: til_89  SP_20-20
					             til_90  SP_21-21
		  tile_name.gif- Graphic showing tile distribution and tile 
				 names.
		  SS_00-00.gif - Graphic showing the image data contained in
				 that specific tile.
**See Tiles.nam file to co-register the database til_00 with the actual
  tile name (ie: til_53 -> SR_13-14, til_54 -> SR_15-16, etc.)
**See tile_name.gif for the Tile name scheme distribution.
1) Go to til_00/cd/PROGRAMS.DIR/PROJ.DIR and type "make" to create 
   the projections library.
2) Go to til_00/cd/PROGRAMS.DIR and type "make -f MAKEFILE" to create
   all the utilities.