
FAO/UNESCO SOIL MAP OF THE WORLD, ERDAS GIS FORMAT

ERDAS image processing and analysis software developed by the
ERDAS, Inc., Atlanta, Georgia, USA supports several file
formats, e.g. LAN, GIS, DIG etc. All the files on this CD 
which has a *.GIS extension are in ERDAS version 7.5 GIS file
format, which will be referred to as ERDAS format (or files)
hereafter. Each *.GIS file has a companion *.TRL file, which
contains additional information about the data. Both *.GIS and
*.TRL files can be read only by ERDAS software and other
software which can import ERDAS 7.5 GIS files. ERDAS software
is also available for UNIX platforms. The newer versions of the
ERDAS software (e.g. version 8.0) on PC and UNIX platforms are
called ERDAS/IMAGINE and they can read the version 7.5 files on
the CD. 

The data are in Binary format (not ASCII). The word length is 
2 bytes per cell.

The first 128 bytes contain the ERDAS file header. The
remaining bytes contain the data written rowwise (NW cell to NE
cell, then next rows, ending with SE corner last cell). For
example, coordinates of the NW corner of the NW cell of the
South America GIS file is: Longitude  -92.0 deg. (West),
Latitude  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 by the file
\RASTEXPN\READEXPN.TXT.  

These ERDAS GIS files exist for 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 NAMSOIL.GIS  792 2016 -180 W  84 N NAEXP.DAT
Cent.America  CAMSOIL.GIS  312  708 -118 W  33 N CSAEXP.DAT
South America SAMSOIL.GIS  834  696  -92 W  13 N CSAEXP.DAT
Europe & W.   EURSOIL.GIS  468 1128  -25 W  73 N EUEXP.DAT
  of Urals
Africa        SOILFIL.GIS  912  876  -19 W  38 N AFLNGX93.DAT
S.E. Asia (1) NSEA180.GIS  624 1056   92 E  29 N SASEXP.DAT
S.E. Asia (2) SEAWEST.GIS  166  120 -180 W -10 S SASEXP.DAT
Far East      FESSOIL.GIS  588 1044   60 E  54 N SASEXP.DAT
Near East     NESOIL.GIS   336  516   32 E  40 N SASEXP.DAT
Central Asia  CNTASOIL.GIS 252  504   46 E  56 N NASEXP.DAT
East of Urals SIB180.GIS   456 1536   52 E  80 N NASEXP.DAT
Australia     AUSSOIL.GIS  408  504  112 E -10 S AUNZEXP.DAT
N.Zealand(1)  NZEANEW.GIS  168  168  166 E -34 S AUNZEXP.DAT
N.Zealand(2)  NZWEST.GIS    47   47 -180 W -42 S AUNZEXP.DAT
                 
