Hi, dear grass-users
The new dimensions (principle components) are formed from the eigen vector (1,
2, 3), not of the factor loadings (W). Therefore there is an error in the
GRASS-wiki - Principal Components Analysis, the line of code error is copied
below:
## Factor loadings (W=385.6992, -364.5920,37.4824,636.0665, etc..) ###
###########################################################
Using the W vector, new maps can be created :
r.mapcalc 'pc.1 = 385.6992*map.1 +636.0665*map.2 + 474.2358*map.3' r.mapcalc
'pc.2 = -364.5920*map.1 + 41.8027*map.2 + 240.4573*map.3' r.mapcalc 'pc.3 =
37.4824*map.1 - 74.7964*map.2 + 69.8356*map.3'
###########################################################
Correct me if i'm wrong?
Thanks in advance
REFERENCES
1. Baronti, S., R. Carla, S. Sigismondi & L. Alparone. 1994. Principal
component analysis for change detection on polarimetric multitemporal SAR data,
Pp: 2152-2154 vol.2154, In: Geoscience and Remote Sensing Symposium, 1994.
IGARSS '94. Surface and Atmospheric Remote Sensing: Technologies, Data Analysis
and Interpretation, International.
2.Fung, T. & E. LeDrew. 1987. Application of Principal Components Analysis to
Change Detection. Photogrammetric Engineering & Remote Sensing. 53(12):
1649-1658.
3. Singh, A. & A. Harrison. 1985. Standardized principal components.
International Journal of Remote Sensing. 6(6): 883-896.
------------------------------
Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902
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