Program Mosaicking
•Initial project focus on acreage indications not mosaic
•Six – fifteen categorized full base Landsat scenes per state
•Radiometric & systematic correction only
lEach unique scene date (Analysis District) produces unique sets of signatures/categories
lProject repeated each year
l
lNeed to create mosaicked state-wide image
•NASS started producing mosaicked images of the CDL Program in 1997 using Erdas Imagine.  The process is human resource intensive as each scene needs to be geo-registered, and each separate analysis district has to be recoded to a master crop list, before they are stitched together.  Since the CDL program grew by about two states a year since 1997, and is re-created each year, an automated solution was investigated.
•EarthSat Inc. GeoCover Program provides ortho-rectified base scenes that the CDL uses as a basis for registration.  Each scene is co-registered to EarthSat's GeoCover LC imagery (50 meters RMS), and then stitched together using the priorities previously assigned from the scene observation dates/analysis districts map.
•A priority scheme is built into the system to allow for scenes/analysis districts with better quality observation dates to be assigned a higher priority when stitching the images together.
•Scenes can be cut/stitched by county or scene edge.
•Clouds are assigned a null value on all scenes, and scenes of lower priority that are cloud free, take precedence over clouded higher priority images.
•Once cloud cover is established throughout the mosaic, the clouds are assigned a digital value.