AI-GEOSTATS: RE: pseudo cross variogram: h=0

2006-09-21 Thread Isobel Clark
PeijunI presume by the "pseudo" cross semi-variogram, you mean the 'non co-located' cross semi-variogram as opposed to the more traditional co-located cross semi-variogram?If so, the difference between the sill of your model and the nugget effect at zero is simply the classical covariance

AI-GEOSTATS: RE: pseudo cross variogram: h=0

2006-09-21 Thread Isobel Clark
PierreIf the relationship between your two variables is negative, the "pseudo" cross semi-variogram will start high and drop off, just like the co-located one. Difference is, the former doesn't go negative, the latter starts at zero and is all negative.One other feature of the "pseudo"

AI-GEOSTATS: RE: pseudo cross variogram: h=0

2006-09-21 Thread Peijun Li
Dear Dr. Clark, Thank you for reply. You know that any point (i.e. pixel) in an image has a value (graylevel value), which is different from sparsely sampling data in geosciences. We use the pseudo cross variogram to characterize the spatial cross correlation between two variables.

AI-GEOSTATS: Re: pseudo cross variogram: h=0

2006-09-21 Thread Isobel Clark
PeijunThat is interesting to hear. I wish you luck in its use. If you are writing any reports, you may wish to refer to our original paper "A novel approach to co-kriging" published in the 1980s and downloadable from my personal site at http://uk.geocities.com/drisobelclark/resume (follow