Preprocessing requirements

Before running this module, the following requirements must be met to ensure the job processes successfully and produces accurate results:

• New imagery is orthorectified
  The new imagery you are adding must be orthorectified, either by running the Orthorectification module, or by other means.

• Mosaic exists
  A mosaic must exist already.

• Data is homogenous
  Typically, you create a mosaic by combining homogenous data. However, you can, if necessary, combine imagery from more than one sensor. If you do so, first consider whether the information is comparable. For example, achieving a suitable output mosaic may not be practical when the bands of the input imagery vary in wavelength.

• Reference image available
  A reference image is required to color balance the new scenes. Typically, the reference image is the low-resolution mosaic preview created by the mosaic-preparation process run on the existing mosaic. The low-resolution image must exist to run the mosaic-update-preparation process.

• Use of local vector masks
  If the input imagery contains features that can cause difficluties with color balancing, such as clouds, bright spots, and dark spots, it is recommended that you create local vector masks in the images to cover the areas of difficulty. Doing so can produce better color balancing.