### Mixture Model

The Mixture Model is a component build as wizard interface and implements raster decomposition using the mixture model strategy. The spatial resolution of remote sensing satellites, in general, allows that a single pixel contains more than a target (for example vegetation + shadow + soil). The mixture model algorithms allow to decompose the raster into fraction images, where the value of the resultant pixels indicate the fraction of each target inside the pixel.

Input:

- One Raster

- A map of pure endmembers, which are pixel values where the user knows the exact proportion of a component.

- Sensor information for each band, if available

The available methods in Terralib are:

- Linear: It is calculated by the following equation:

- r i is the pixel value at band i,
- a ij is the known value of the component j at band i,
- x j is the proportion of component j,
- e i is the estimation error for band i.

- PCA: The component matrix is transformed using Principal Component Analysis, and the fraction of each component is obtained by using the proper number of eigenvectors.

It is accessible through:
Layer Explorer > Right Click over a Layer-name > Raster Processing > Mixture Model... (applies on selected layer)
Raster Processing > Mixture Model... (list of all layers will be available)
This wizard consists of the following steps:

#### Wizard Page 1 - Selection of the layer with the desired raster (Layer Search).

NOTE: This page will only appear if the user has accessed the mixture model operation from the menu "Raster Processing".

#### Wizard Page 2 - The mixture model interface.

To execute this operation is required the following steps:

1. Select the type of mixture model to be used and set specific parameters (the parameters will vary depending on the selected contrast type).
2. Optional parameters:

- Normalize output: indicate that output raster will be normalized, by default [0, 255].
- Create error images: indicate that output raster will include the error bands.

3. Select the input bands and the sensor information for each band.
4. List of acquired components.

The acquisition of components is achieved by selection of samples over the raster. The wand button will display the Raster Navigator Interface, enabling the acquisition of components.

#### Wizard Page 3 - Output information (Output Raster Information).

The result of this operation is shown in the figure below.

- Original Image

- Mixture Model result.

- Band 0 - Soil representation.

- Band 1 - Shadow representation.

- Band 2 - Vegetation representation.