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ENVI

Load Rule Images and Preview

Load Rule Images and Preview

In Step 7 of the Target Detection Wizard, you load the rule images that ENVI created during target detection processing.

The first rule image listed in the Target and Method columns is automatically loaded into a display group with a Square Root stretch applied. Binary Preview mode is automatically enabled, and you should see detected target pixels highlighted in the color you specified in Step 3 (Select Target Spectra). The Target Pixel Count tells you how many pixels ENVI found that matched your target spectra.

Note: If you are viewing very large images, you may want to disable the Binary Preview check box.

To display other output, do the following. Any selections you make are automatically reflected in the display group.

  1. Select one Target from the column.
  2. Select one Method from the column.
  3. The new target and/or method are loaded into the display group. When you select MTMF and MTTCIMF results, a 2D Full Band Scatter Plot opens.

When viewing results that include a Full Band Scatter Plot, a good region to visualize is one defined by high detection scores and low infeasibility values.

Though similar to the 2D Scatter Plot, the Full Band 2D Scatter Plot view is constructed from the entire band, not just the data visible in the Image window view. When the view in the Image window changes, the view in the Full Band Scatter Plot does not. When you select different regions in the Full Band Scatter Plot, the highlighted pixels in the Image, Scroll, and Zoom windows update.

Dancing pixels, density slice, and menus are not available. Use the following mouse buttons in the 2D plot:

  • Draw polygons using the left mouse button. Left-click in the scatter plot to define the vertices of a new polygon that will select pixels. Right-click to close the polygon.

Note: Clicking the middle mouse button before you close the polygon erases it.

  • Resize the scatter plot using the middle mouse button. Click the middle mouse button, grab the corner of the window and drag to the desired size. To reset the plot to its default size, middle-click anywhere on the plot.

Note: Resizing the scatter plot causes any drawn polygon(s) to be reset.

  • Erase all drawn polygons by clicking the middle mouse button outside of the scatter plot.

To further refine the display, you can do the following:

  • To apply a different stretch to the display, select from the Default Stretch drop-down list. Square Root is typically a good stretch when the target pixels occupy a small population of the image.
  • For MF, CEM, ACE, SAM, OSP, and TCIMF: ENVI uses a default thresholding value. To apply a different Rule Threshold, move the slider or enter a new value. If the rule value is larger than the threshold, the pixel is highlighted in the display. Adjust the threshold to a higher value to select fewer pixels, and vice versa.

Note: Threshold settings behave in the opposite manner for SAM since lower values represent a high probability of being a target in the SAM rule image.

When you have finished loading and previewing the output images, click Next. The Target Filtering panel appears.



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