How to fill an AOI with a constant value?
The procedure for changing the pixel values inside an AOI has changed since the previous version. The Area Fill tool is opened by highlighting the image in the Contents panel and then selecting the Fill icon found in the Edit group under the Multispectral or Panchromatic or Thematic tab depending on what type of data you have displayed in the Viewer. The other “Area Fill” tool found under the Drawing tab is actually just a color chooser used for selecting the style to fill AOIs.
If using a Panchromatic or Multispectral image, a warning message will pop up saying "Since this function modifies the pixel values of the image, you may wish to recalculate the statistics and histogram for the layer before doing any other operation that depends on this data.” Click OK. Save your image. Remove your image from the 2D View and redisplay it.