Why are there often black grids superimposed on 2-D scatterplots in ENVI? 6/9/1998 Note: This help article applies only to Classic ENVI, and not to the new interface that was introduced with ENVI 5. Many ENVI users have noticed that when they display a 2-D Scatterplot in ENVI...Read More >
Tips for georeferencing AVHRR images in ENVI 6/9/1998 ENVI offers a utility that georeferences AVHRR level 1b images using the geo-location data embedded in the Level 1b data file. There are a number of issues that should be considered when using...Read More >
How does ENVI's Pixel Purity Index Work? 6/9/1998 ENVI includes a tool called the Pixel Purity Index, which can be used to locate the purest pixels in a multispectral image. This tool was designed by one of the ENVI developers, and is unique to...Read More >
Why is constrained unmixing usually a bad idea? 6/9/1998 The equations used for spectral unmixing (also known as spectral mixture analysis) can include constraints that the pixel fractions calculated for all endmembers be between zero and one (i.e.,...Read More >
What are the algorithms that ENVI uses for RST and first degree polynomial warping? 6/9/1998 When performing any type of image warping in ENVI, one can choose an RST, Polynomial, or Triangulation warping algorithm. Many ENVI users wonder what the difference is between an RST warp and a...Read More >