Ternary plot

Ternary plots are RGB maps of spectral band ratios, which take advantage of known absorption spectra to highlight mineral groups. The ternary plot takes three band ratios and assigns them to red, green, and blue so mineral species highlighted by ratio one will stand out in red, ratio two in green, and ratio three in blue.

Usage:

• Click Band algebra in the Processing toolbox, then click Mineral indices.
• Select the layer you want to derive mineral indices from in the Product dropdown menu.
• Choose three indices you'd like to highlight in your ternary plot.
• Enter text in the Output layer name field to name your ternary plot.
• Click the Calculate indices button to create your ternary plot.
• If your layer looks washed out, go to the Raster layers menu and click the settings icon ( | ) for your ternary plot.
• Assign each mineral group to the color you want using the Red, Green, and Blue dropdown menus.
• Click Calculate histograms to see the distribution of values in each band within the current viewport.
• Enter numbers in the Min and Max fields to ensure that the minimum and maximum values for each color fall within the following ranges: 1.9--2.2 for Red, 1.0--1.5 for Green, and 0.9--1.1 for Blue.
• Click the Apply button.

Tips:

• All band ratios have non-zero values. So even if your area of interest doesn't contain a particular mineral group, the ternary layer may give you the impression that it is present. This is where user knowledge of the site is important.