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Statistics

  • Produce graphic or numeric frequency histograms of images or signature files.
  • Extract summary statistics including minimum, maximum, total, sum, average, range, population and sample standard deviation for pixel groups.
  • Evaluate relative richness, diversity (entropy), dominance index, fragmentation index, number of different classes, center versus neighbors and binary comparison matrix pattern measures.
  • Calculate a relative frequency image of non-zero values over multiple images.
  • Perform simple linear regression, multiple linear regression, and logistic regression analysis between two images or attribute values files.
  • Calculate the best fit using up to a 9th order trend surface to a set of irregular cell control points by least-squares procedures.
  • Compute Moran's I first lag autocorrelation statistic for an image, along with confidence test.
  • Compute the density, variance and variance-mean ratio of quadrat cell counts.
  • Compute mean center (weighted or not) of a point distribution and standard radius.
  • Compute the compactness ratio of polygons given corresponding area and perimeter images.
  • Determine all unique combinations of values in two qualitative images. Crosstabulate, crosscorrelate and calculate similarity statistics for image pairs.
  • Compute statistics for measuring the similarity between two qualitative images, including specialized Kappa measures that discriminate between errors of quantity and errors of location.
  • Measure the correspondence between a quantitative modeled image showing the likelihood that a particular class exists and a Boolean image of that class as it actually occurs.
  • Create systematic, random and stratified random point sampling schemes.
  • Create random images according to rectilinear, normal or log-normal models.
  • Convert an image to standard scores.
 
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IDRISI provides statistical tools for spatial analysis of raster images, including simple regression, autocorrelation analysis, pattern analysis, trend analysis, logistical regression, and many more. Here a multiple regression analysis was performed to relate crop use intensity in Zimbabwe to elevation, cost-distance to markets, rainfall and variation in rainfall. The prediction and residual images are shown Prediction and residual images

 

 
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IDRISI supports import and export to SPLUS. Working in SPLUS, users can import and export directly to IDRISI raster and values files using a command window interface in SPLUS. Results of a fire danger study are shown in the small image at the lower left. To make the image more dramatic and interpretable, an elevation model was used to calculate a hillshaded relief image for the area (upper left image). This was enhanced and merged with the classified image to produce the final relief-shaded fire danger image. SPLUS Import

 

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