Charles
Image resolution has a major impact on range calculation. For an image with fine resolution, spatial modeling implies resolving details at that spatial scale. Take topograpy as an example, DEM resolution at the scale of grain might resolve variability at that scale. DEM resolution at the scale of clod might resolve variability at that scale. These is some sort of heirarcy associated with spatial scale where each scale is nested in the next spatial scale. In the case of topography, as one move from small scale to larger one, variogram modeling will correspond to higher range calculation.
Thanks Abedini On Mon, 20 Feb 2006, Charles Serele wrote:
Dear list members, Does anyone can help me understanding variogram range interpretation or send me some specific references. I am currently analyzing variograms computed over the same site of a remote sensing image. The first variogram was derived from the original image and the second one was derived from the transformed image (using a mathematical model). All the variograms were fitted with an exponential model. The range value I got from the transformed image is higher than the one from the original image. I would like to know: 1. For ranges of 4 pixels (original image) and 9 pixels (transformed image), does this difference can impact significantly on a ground sampling for instance ? What should be the acceptable range difference ? 2. In terms of spatial correlation, can we say that a high range value is associated with a less spatial correlation between data points (pixels)? On other hands, the spatial information content was reduced by the transformation ? 3. Can we say that data with small variogram range is more heterogeneous than data with high variogram range ? Regards, Charles
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