Spectra Projector displays spectra as points on a 2D plane or in a 3D space. A combination of two principal components, which make up the 2D projection plane, can be selected in the tab control. If you are viewing PCA results using the 3D projection mode, you can select a combination of the three associated principal components.

If you click, for example, the 2D projection tab captioned “2-5”, the spectra will be projected onto the plane of the 2nd and 5th principal components. The number of tabs is determined by the number of principal components that have been selected in the Spectra Classifier module. Spectra Projector displays a tab for every possible combination of the selected principal components. For example, if you have generated Spectra Projector with 3 principal components, 3 tabs will be available (1-2, 2-3, and 1-3). For the 5 (default) principal components, 10 tabs will be available (1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, 3-4, 3-5, and 4-5). The same principle applies to the 3D projection mode. Please note that in the 3D mode the number of combinations of principal components for more than five components is significantly higher in comparison to 2D. Therefore, if you want to analyze your spectra in the 3D mode, you should not use more than five principal components. The number of principal components can be set in the Spectra Classifier window prior to the PCA calculation.

The status bar in a Spectra Projector window is divided into three parts. The left part informs you which principal components have been selected. The middle part displays the type of spectra transformation that has been utilized for classification. The right part shows how many spectra have been classified (the total number of spectra from all groups).

Spectra Projector allows you to enlarge any region of the projection plane independently, for each combination of principal components, by using the LEFT mouse button. To get the original scale, simply click the Zoom Out button, which will appear in the top left corner of the projection plane after any change of scale. In the 3D mode it is not possible to enlarge the projection.