FAO/UNESCO SOIL MAP OF THE WORLD FLAT BINARY FILE (IDRISI) FILES


Flat raster or binary information (BIN) files do not have any  header and the data is recorded 
continuously and can be read by most GIS and image processing software.  When such files have 
*.IMG extension and an auxiliary information file called document file, which has *.DOC extension, 
then they can be read by IDRISI software (version 4.0). IDRISI is a GIS and Image Processing  
software for PCs developed Clark University, Worcester, MA, USA. Therefore we will refer to such 
files as  IDRISI files. 

There are several types of IDRISI *.IMG files. On this CD they are all binary integer files, where each 
cell is represented by two bytes. The *.DOC files are ASCII files which contain some  information 
about the *.IMG files. Printout of one, South America *.DOC file, is listed below:  

file title  : Soil Map of South America
data type   : integer
file type   : binary
columns     : 696
rows        : 834
ref. system : lat/long
ref. units  : deg
unit dist.  : 0.0833300
min. X      : -92.0000000
max. X      : -34.0000000
min. Y      : -56.5000000
max. Y      : 13.0000000
min. value  : 0
max. value  : 6998

(*.DOC files contain other items such as "legend categories", etc. For the files on this CD, their values 
should be ignored.)

As it can be seen from the *.DOC file listing above, which corresponds to the South America raster 
image data file (SAMSOIL.IMG) has  834 rows (West to East) and  696 columns (North to South).  
Coordinates of the NW corner of the NW cell of the South America file are : Longitude (min. X) -92.0 
deg (West), Latitude (max. Y) 13.0 deg (North). The coordinates of all the other cells can be calculated 
easily as the map is in Geographic (Latitude-Longitude) Projection.

For each cell, the composition of the soils, texture, slope etc. can be obtained from the CSAEXP.DAT 
file which is located on  the directory \RASTEXPN. Its format is described in the file 
\RASTEXPN\READEXPN.TXT. 

IDRISI files are provided for the land areas of the whole World (except part of the Pacific Islands and 
Antarctica).  The different files, number of rows, number of columns, longitude and latitude in deg. of 
the NW corner, and name of the corresponding Long Expansion file are listed in the following  table:
	
Main Region   File Name    Row Col. Long.  Lat.  Expansion file

North America NEWNAM.IMG   792 2016 -180 W  84 N NAEXP.DAT
Cent.America  CAMSOIL.IMG  312  708 -118 W  33 N CSAEXP.DAT
South America SAMSOIL.IMG  834  696  -92 W  13 N CSAEXP.DAT
Europe & W.   EURSOIL.IMG  468 1128  -25 W  73 N EUEXP.DAT
  of Urals
Africa        AFSOIL.IMG   912  876  -19 W  38 N AFLNGX93.DAT
S.E. Asia (1) SEAEAST.IMG  624 1056   92 E  29 N SASEXP.DAT
S.E. Asia (2) SEAWEST.IMG  166  120 -180 W -10 S SASEXP.DAT
Far East      FESSOIL.IMG  588 1044   60 E  54 N SASEXP.DAT
Near East     NESOIL.IMG   336  516   32 E  40 N SASEXP.DAT
Central Asia  CNTASOIL.IMG 252  504   46 E  56 N NASEXP.DAT
East of Urals SIB180.IMG   456 1536   52 E  80 N NASEXP.DAT
Australia     AUSSOIL.IMG  408  504  112 E -10 S AUNZEXP.DAT
N.Zealand(1)  NZEANEW.IMG  168  168  166 E -34 S AUNZEXP.DAT
N.Zealand(2)  NZWEST.IMG    47   47 -180 W -42 S AUNZEXP.DAT
 
