Crop Scouting
Richard Douglass
Instructor of Agriculture Technology at Southeast Community College, Beatrice, Nebraska, USA
February 22, 2003
Southeast Community College Campus
For the last 4 years we have been teaching Ag Tech students how to use KAP as a tool for crop scouting. Traditionally crop scouting involves walking around in the field, sometimes using a random pattern, hoping to locate problems, confirm growth progress, and "scout" for moisture, insects, disease, plant population, etc that help a producer make management decision regarding irrigation, chemical application, or crop rotation for the next season. Sometimes this is a custom hire service, sometimes it is the producer that does the scouting.
At Southeast Community College we will have two sections of 15-20 students every 10 weeks. Normally, if weather cooperates, we will make about 3-4 KAP excursions per group and can gather from 22-35 photos per flight. After 4 years of using KAP we have an archive of over 2500 photos of College fields and rural structures. The school farms, with the students, 370 acres, some under irrigation, but mostly dry land. This is a Technical Agriculture program where hands-on experience makes our graduates a commodity in high demand.
We have invested about $1000 for the kite, string, camera, remote control and wireless viewfinder. There is little or no recurring expense, once equipped.
In general, this is a relatively safe and reliable technique. Personal safety is much improved when individuals remain on the ground when compared to attempting photography from an aircraft. Equipment safety, however can be compromised with poor quality knots, frayed line, and or gusty wind conditions. In 3 years we have experienced 3 line failures. The first did not result in any serious damage. However the last two mishaps resulted in approximately $1000 in broken equipment. Two cameras are now paper weights and the crystals from the radio control needed to be replaced.
The technique involves using a 15-60 sq ft kite, 300 lb test line, and a camera mounted in a remotely controlled cradle, total weight of about 2.5 lbs. Allowing the kite to fly at 500-1000 ft altitude requires about 2000 ft of line and a suitable winder.
Each photo will contain from 5-10 acres in a straight down shot, depending on altitude. If you move the winder, and do not have obstacles, there is only the limit of your energy and the number of photos per data card (a 64 Meg card will handle 36 photos with our FujiFilm 4700 camera) and you can purchase 128 or larger cards.
A large operation would be more likely to choose an airplane for their aerial photography. Here in Nebraska, 75-80% of the days are suitable for KAP. No wind (under 5-8 mph) or too much wind (over 25 mph) makes this less than fun but still possible in a pinch. If there are patchy clouds that cast shadows on the field, they cause problems. An overcast day or uniform cloud cover is not a problem. We have not had much success before 8 AM or after 6 PM in the summer. The pictures are fun to look at, but the detail is not there due to the long shadows.
I have taken photos by myself on a number of occasions and the equipment is designed to do this. Up to a dozen people can be used, splitting them into teams and assigning different tasks to each team. It is nice to have your crew scattered around the target field and then you can more accurately estimate the position of the camera. When you are alone and trying to move the winder around, you have difficulty estimating how far the camera is downwind. Sometimes you will be actually photographing the field across the road, instead of your target field.
We use 2 ft x 2 ft ceiling tiles as visible targets and gather GPS coordinates on those points. This allows us to overlay the pictures on our yield maps. There is always some distortion on the edges of any picture. We have actually spent most of our time gathering photos and not as much time pasting them onto the map. This is a routine activity for those who use FAS aerial slides and have them as backgrounds for their yield maps.
Other than Dr. Ferguson at Clay Center, NE., we do not know of any others who are using this low altitude Aerial Photography technique for crop scouting purposes. At Clay Center, they use a fixed wing airplane with a 6 ft wingspan and fly passes over the field. They have had some good success, but it takes a crew of 4 and the training level is considerable.
We have had excellent success with a FujiFilm 4700 zoom camera and a 64MB Smart Media card. It allows us 36 high resolution (4.3 Million Pixel file) photos, each take about 1700-1800KB of space. This is not a reflex camera. We have had limited success with a miniature video camera/transmitter ($350 US) but it only transmits a suitable image for about 300 feet. I have been told, that there is a resistor that can be clipped that will increase the range but have not followed up on that tip. We use the video camera as a wireless viewfinder, so we can see what we are taking with the digital camera. You could record the video image for reference purposes. We use Adobe Element's "Panoramic" feature to stitch together the photos and create a composite picture from a series of our images. This quickly gets too large for us to print, so we often project them on a screen.
All of the hardware for Kite Aerial Photography can be purchased from commercial sources. The radio controls from any major hobby outlet that caters to radio controlled airplane enthusiasts, Kites from IntoTheWind or another commercial kite store, line and winders from the same source. Cameras are readily available on the Internet. Currently I would recommend FujiFilm's 601 model. Assembly of the "rig" to carry and aim the camera will take about 8 hours of time in most basement shops where you have access to an assortment of plastic, screws and sprockets. The primary objective is light weight, rather than beauty, with a some emphasis on durability. We have found that a discarded VCR has many of the components needed.
The most recent mishaps have caused us to evaluate the use of two "recovery" features. One is a parachute normally sold for use in recovering model rockets, and the other is a audible signal used to locate downed model airplanes. The parachute would hopefully slow the decent of the camera rig should it become detached from the line, or in case of a line failure. The audible signal could be used to locate the camera rig during the first few hours after a crash. Another thing we learned the hard way should you have a mishap occur, was to lay down the winder, have everyone mark their positions and memorize the last sighting of the camera and kite. Then by using triangulation, you increase the odds of finding the downed components.
I have found of great interest the Colorado State University Climatology site on the Internet. If you do a search for Wind Tram and Mike Jensen you will find some research in Climatology. They fly their kite very high (11 miles up) and then "fly" a wind tram up and down the line gathering information. They leave the kite up for several days using this procedure.
We have had considerable success using KAP for crop scouting. The attractive cost and capabilities of this technique have attracted a high level of interest.
This is not Richard Douglass' first appearance on the Internet KAP scene. James Aber has a page about Richard Douglass' work that was first published in 1999.
[Click Here]
More of Richard's KAP can be seen at the following links;
- Richard's Home Page
- Another gallery of KAP images. - You must click on "guest viewer" then type Richard's email address -- rdouglas@southeast.edu
A short article can also be found on the Blue River News site about the college's crop scouting program.