On Wednesday 04 of December 2013 16:22:51 Nikos Alexandris wrote: > Nikos Alexandris wrote: > > > The i.pca module in G7 offers a "forward/filtering/backward" PCA. I > > > have > > > an issue first with filtering and second with rescaling. > > > > > > 1) I can't see any differences in the derived Principal Components > > okay, to clarify: I mean the resulting images which, initially are Principal > Components (synthetic images) and, after applying filtering & backward PCA, > the resulting images approach the original data -- still they are modified.
Example (using i.pca in G7, though r.info below executed from G64): <http://nikosalexandris.net/owncloud/public.php?service=files&t=e87b1223bf6402786ef7478690099602> and details for P=90) r.info -rh PC90N.1 min=171.596979136065 max=1107.42672094831 Data Source: Data Description: generated by i.pca Comments: Eigen values, (vectors), and [percent importance]: PC1 2.78 ( 0.4947, 0.5922, 0.5743, 0.2735) [69.53%] PC2 1.08 ( 0.5196, 0.0517,-0.0974,-0.8473) [26.99%] PC3 0.11 ( 0.4210, 0.2486,-0.7926, 0.3644) [ 2.86%] PC4 0.03 (-0.5551, 0.7647,-0.1805,-0.2729) [ 0.63%] i.pca -n -f input="Blue_DNs,Green_DNs,Red_DNs,NIR_DNs" output_prefix\ ="PC90N" rescale=0,0 percent=90 P=70) r.info -rh PC70N.1 min=171.596979136065 max=1107.42672094831 Data Source: Data Description: generated by i.pca Comments: Eigen values, (vectors), and [percent importance]: PC1 2.78 ( 0.4947, 0.5922, 0.5743, 0.2735) [69.53%] PC2 1.08 ( 0.5196, 0.0517,-0.0974,-0.8473) [26.99%] PC3 0.11 ( 0.4210, 0.2486,-0.7926, 0.3644) [ 2.86%] PC4 0.03 (-0.5551, 0.7647,-0.1805,-0.2729) [ 0.63%] i.pca -n -f input="Blue_DNs,Green_DNs,Red_DNs,NIR_DNs" output_prefix\ ="PC70N" rescale=0,0 percent=70 Nikos _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
