Case 1 : Monitoring Farmlands, Nebraska
Project and the Challenge
The USDA’s National Agriculture Imagery Programme (NAIP) monitors US farmlands through aerial imagery. NAIP hires contractors to fly over and photograph farmlands within the 26 states it oversees.
They then process and map the collected imagery and determine factors including crop locations, size, quality and crop management. NAIP was looking for two results it wasn’t getting from traditional film methods: quicker turnaround time/product delivery and the simultaneous delivery of colour and colour infrared imagery. In July 2003, NAIP decided to obtain its imagery in a new way- digitally.
NAIP leaders believed digital sensors could deliver the results and chose to test the new technology in Nebraska. This was no small task- they needed aerial imagery of approximately 90,000 square miles or 5900 digital ortho quarter quads (DOQQs) of agricultural land. NAIP contracted North West Group, EarthData International and Horizons, Inc. for the task. The companies had a 90-day deadline: 60 days for acquisition, 30 days for processing.
The magnitude of this project made it the largest digital ortho project ever attempted to date. The digital sensor charged with successfully carrying out the project was the Leica ADS40 Airborne Digital Sensor from Leica Geosystems GIS & Mapping.
Within three weeks, the contractors obtained imagery of all 90,000 square miles of Nebraska farmlands. The state was split into 120 flight lines and required about 90 hours of flying time. The flight crews mounted two ADS40 sensors into two Cessna 441 Conquest propjets. The field crews processed their ADS40 data in the field immediately after flight missions, allowing them to verify successful capture and coverage while still in the field.
Because the ADS40 captures imagery strips seamlessly, the amount of image mosaicking the teams needed to carry out was drastically reduced when creating their client’s radiometrically balanced final product. Furthermore, the ISTAR and GPro processing infrastructures allowed for repetition and automation of steps like rectification and automatic point measurement and allowed for parallel processing.
The contractors acquired and processed all of the aerial imagery within the 90-day timeframe. With digital imagery, the teams were able to invest time in data processing to ensure the high quality of the end product. The success of such a large project opens the door for other states to use digital imagery for their ortho-imagery-related needs including GIS database update, emergency planning, growth planning and more. North West has fielded several requests from other state government organizations interested in using the ADS40 for imagery acquisition.
Nebraska was a pilot project for NAIP to determine if a digital sensor was able to deliver higher-quality results in a shorter period of time. The ADS40 proved it was capable of successfully handling large-scale projects. Moving forward, sensors will compete equally with film cameras for NAIP contracts starting in 2004.