These images was imported from the CDROMs to the 
computer hard disk, converting them to the .IMG 
format, using the IMPORT module of the software 
ERDAS Imagine release 8.2. The chart edition was 
made using a PC Hewlett Packard Vectra 500, 
160mhz, with 96 Mbytes RAM, and a total of 6 Gbytes 
in H.D. 
procesed, obtaining the ellipsoidics coordinates of the 
GCPs in the WGS’84 system. 
2.- Ellipsoid change: because the República 
Argentina reference ellipsoid is the Hayford 
International, an obtained coordinates conversion was 
realized using the Molodensky formula: 
In order to choose the G.C.P. that we needed to the 
rectification and georeferentiation, we printed the band 
#4 of all the images, in 1:250.000 scale. In this hard 
copies we choosed the zones of interest to localize 
control points, which make up the following 
conditions:(Romeo, Pineda y Arbiol 1995) 
• Viewables zones in the largest number of 
overlapping images. 
• Corners of images. 
• Proximity of communication ways to simplify the 
access of the land groups. 
• Natural or antropic forms with time sojourn. 
A<(>"= - 
-sen<(> cos^Auf 
-sen<|> senXAwj 
+ cos<)>A«3 
+ (aaNe 1 sen<|> cos<t>) 
► cosec Y'/(M + H) 
/ a + Aa 
A/(l-a) ' 
_+ jV(l-a) 
sen<j> cos<|> 
Ak”= 
- sen Mw, c 
+ cosÀA u\ 
cosec 1' 7(W + //)cos<t> 
Based of this advances we selected between 8 and 12 
zones per image with communication ways 
intersections between them or with rivers, in which we 
could localize the point quickly in the land. Defined 
these zones we printed them using bands 2, 3 y 4, in 
1:100.000, 1:50.000 and 1:25.000 scales, for a more 
exact location of the point in the land and its 
correspondece with the images pixels. 
AH = cos<)> cosXAuf + cos4> senXAw^ 
+ sen 4>Aw 3 c - aAa / jV + Aa (l -a )N sen 2 4> 
Where: 
Survey campaigns was realized to collect the GPS 
coordinates of the ground control points selected. To 
carry this out, two groups were formed, each one 
compossed of a profesional (profesor) and one student. 
Each goupe is traveling in a pick-up, and has a 
TOPCON GPS geodetic receptor, model Turbo Sll of 
double frecuency whose precision is bigger than the 
precision requirements (about pixel, 15 metres in this 
case). Because on this campaigns we spent several 
days and as any receptor can acumúlate only four 
hours of surveying data, each group also had a 
Notebook PC to be able to download the data and 
continue with the recepting process. This equipment 
was completed with a cellular telephone. 
Auf are the translation parameters between ellipsoids 
centers (DMA parameters were used); 
N is the normal radius of the terrestrial curvature whose 
value is for the international ellipsoid: 
N = 6389135.050 -10774.2275 cos4> 
27.2534cos 2 <j> - 0.0766cos 3 2<j> 
e is the first excentricity, whose value for the 
international ellipsoid is: 0,081991889979 
During these campaings we realized identifications and 
recognitions of the main feature patterns of land use, 
viewable in the images. This job was registred in colour 
prints hardcopies in 1:100.000 scale that we possesed 
to carry out this work. 
When the data was collected, the data process began 
which have three steps: 
M is the curvature radius of the meridian that for the 
international ellipsoid has the value: 
/ 
M = 6399936.608/ 
V 
1.00169061346 
+ 0.00168918679 cos 24» 
-0.00000142427 cos 2 24» 
+ 0.0000000240COS 3 24» 
V 
y 
1- G.C.P. coordinates calculation: with GCP 
equipments software the land observations was 
H is the geometric height to the physic surface of the 
earth.