As harvest begins to ramp up throughout Iowa, many individuals shall be evaluating their crop scouting actions from 2021 and beginning to make plans for 2022. In a (*3*), we outlined choices for capturing imagery of your fields to assist in scouting and making administration choices. Fall is usually a nice time to seize imagery to grasp crop dry down, late season weed stress and crop lodging. As you think about remaining imagery wants for 2021 and make plans for 2022, there are three traits of images it’s best to perceive:
- Picture Decision
- Picture Timing
- Picture Kind or Spectral Bands Captures
1. Picture Decision
Picture decision is the measure of the land space represented in a single pixel of your picture. A picture for a low-altitude UAV flight is likely to be round 1 sq. inch per pixel, whereas a satellite tv for pc picture could also be 6 sq. toes per pixel. With each UAVs and manned plane, decision relies upon on the digicam used and the flight altitude. Flying decrease will improve decision, however will even improve flight time and require a lot of passes throughout the sector to finish a map.
The extent of decision you want relies upon on your supposed use for the imagery. To easily doc drainage points and ponding, satellite tv for pc imagery could also be appropriate. Nonetheless, when you’re seeking to conduct plant stand counts or assess emergence points, larger decision pictures (possible from a UAV) shall be needed.
2. Picture Timing
Timing your imagery seize with the climate is essential to getting top quality pictures. Nonetheless, it’s simply as essential to think about the expansion stage of your crop when deciding when to conduct a flight. Flying too early within the season when not a lot plant development has been established above the soil may end up in a picture that reveals largely soil. Flying too late can typically hinder your skill to determine points with planting, emergence and early season improvement. Figures 2, 3, 4, and 5 present aerial pictures taken of the identical discipline a number of weeks aside. Notice: These pictures are from 2019, which got here with a moist spring and delayed planting on this discipline. The quantity of soil seen in these pictures shouldn’t be more likely to be seen in June in a mean yr.
3. Picture Kind or Spectral Bands Captures
A preferred picture sort for assessing fields is a NDVI (normalized distinction vegetative index). NDVI makes use of an NIR (close to infrared) picture to generate the NDVI map. Time pictures proven in Determine 6 show the uncooked NIR picture on prime and the ensuing NDVI picture on the underside. The near-infrared mild bands can typically show completely different traits than conventional RGB shade pictures. The NDVI map highlights these variations by displaying them with various colours.
Different indexes are additionally obtainable and require completely different inputs when it comes to mild wavelength recorded by the digicam. A VARI (seen atmospherically resistant index) will typically look just like NDVI, however makes use of an RGB photograph enter and emphasizes completely different crop traits.
These indexes typically look and are seen equally to a mix yield map. It’s essential to grasp the colour variations and the way they had been assigned to indicate variations in crop vigor. Indexes are a approach to categorize and differentiate information factors to make variations simpler to determine. These indexes typically might show areas of decrease or larger yield, however perceived poorer areas of a discipline in a picture should still yield in addition to different areas. The picture doesn’t all the time predict a yield distinction.
When deciding to incorporate aerial imagery as a part of your administration plan, it’s essential to grasp not solely the method of capturing pictures, however the choices and changes that may have an effect on the standard of your picture. Take time to guage your crop scouting wants and take these traits into consideration earlier than heading to the sector or scheduling a flight.
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