• TerrAvion TerrAvion
    • Jul 30
    • 9 min read

    Aerial imagery for agriculture: learning the basics

    Aerial imagery is a powerful tool that can transform any modern agronomy program into a more profitable system. However, many growers are not familiar enough with what imagery has to offer to consider it as part of an agronomy solution. Let's break down the basics of aerial imagery for agriculture.

    Image resolution

    satellite resolution comparison To start, let's talk about an important component of all imagery data; resolution. Image resolution is the detail an image holds. Resolution refers to the number of pixels in an image, and a pixel is the smallest element of a digital image. Each image is made up of many tiny pixels. Higher resolution means smaller pixels, and more of them, resulting in more image detail. The amount of resolution you need depends on what you're trying to do. If you are using an aerial image to map out driving directions, a low-resolution satellite image will do the trick. If you are using imagery for agricultural purposes, to monitor your crops and guide management decisions, a high-resolution image is required. For instance, a high-resolution image may clearly reveal signs of crop stress that are not observed in lower resolution imagery. Any modern agronomy program is only as good as the quality of data that powers it, and high-resolution imagery is an essential piece of data for any successful agronomy program.

    Various image layers

    TerrAvion Natural ColorNatural Color

    When you hear the term aerial imagery, you are probably thinking of what you would see if you were flying in a plane, which is a natural color or RGB (Red Green Blue) image. This is the type of image that your regular camera captures and what you see with your own eyes. Natural color imagery is not the most important layer for making management decisions, but it still provides excellent value for a variety of use cases. In particular, natural color imagery is an excellent tool to identify storm damage and soil issues. Other yield-robbing problems can also be identified in natural color images, but natural color imagery is mostly used as a contextual reference layer to support some of the next image types we will discuss.

    website infrared-1

    Infrared or Color InfraRed (CIR)
    Infrared imagery has been used for decades in agriculture as a plant health indicator. Infrared data measures the red light reflection of a plant which corresponds to plant biomass. Plants with dense biomass will reflect more light and appear more red in an infrared image. Infrared imagery is still a valuable tool for indicating plant health, but nowadays, another type of data as the most widely used image type for assessing crop health.

     

    website ndvi-1Normalized Difference Vegetation Index or NDVI

    NDVI is the crop health image that growers use to identify crop stress. NDVI imagery is a vegetation index that measures plant biomass along with photosynthetic activity or the presence of chlorophyll. NDVI is a combination of infrared data and the red (R) band of color in RGB imagery, which has shown to correlate to photosynthetic activity or chlorophyll levels. Each NDVI pixel gets assigned a value from 0 to 1, with 0 representing dirt with no vegetation growth and 1 representing vegetation of the highest possible vigor. These pixels are then colorized, creating a crop health image such as the green image shown to the left. High-resolution NDVI imagery can reveal stress in plants that is not evident even when you are on the ground level, looking directly at the plant. Because of this, NDVI imagery has great value in identifying yield-robbing issues well before they become evident to the naked eye.

    website thermal-2Thermal

    Thermal imagery is data that illustrates thermography information for a field and is only available through crewed aircraft or drones, not from satellites. Because thermal imagery is being captured from the sky, a thermal image is not an exact measurement of ground temperature. It will, however, tell you ground temperature within a few degrees, but more importantly, it will reveal any slight variation in temperature in a field, which is very valuable information when it comes to managing irrigation, drainage, and any other moisture-related issues. Thermal imagery can also add context to issues revealed in the other image layer such as NDVI, natural color, or infrared. Thermal data often has a lower resolution than the other three image types.

    New image types

    pan synThe above-mentioned image layers are the core four imagery products available to growers today through TerrAvion. TerrAvion provides all of these layers for every subscription at one flat rate. For 2019, TerrAvion has added another two products to our core product line; the Pansharpened Thermal image, and the Synthetic Color image. The TerrAvion pansharpened data layer is a combination of our current thermal image and the higher resolution infrared data. This combined product allows you to see field characteristics such as crop rows or other plant signatures that are clearly visible in infrared imagery but are not visible in our standard thermal product. Similarly, the TerrAvion Synthetic Color imagery is a combination of our natural color product and infrared product, offering better definition and detail in images where factors such as poor lighting can result in natural color imagery that lacks contrast and appears dull in color.

    Service types: subscription vs. one-shots vs. historical images

    One-shots

    Aerial imagery services can generally be separated into two categories; single image or one-shot services, or subscription services. A one-shot service is a service where only one image is delivered. If a grower believes they are only going to use imagery for one specific case and don't require multiple images, one-shots are a good option. One-shot services are common with drone imagery providers because drone imagery is expensive, and achieving ROI with drone subscription services is not easily achieved due to the higher cost.

    Subscription Service

    Subscription services provide multiple images throughout a growing season. The number of image deliveries for subscription services varies, as do the flight schedules. Some providers offer a few flights with a more flexible schedule, while others, such as TerrAvion, offer various subscription services that adhere to a fixed flight schedule. Following a set flight schedule for subscription services allows imagery providers to streamline their operations, operate at a higher efficiency, and offer lower prices. Satellite providers offer subscription services because their satellites are always capturing imagery, so there isn't much difference in overhead cost for providing one image compared to many images. Satellite image deliveries are offered on a very fixed schedule as they only get one chance to capture an image as they rotate the earth. This can lead to problems when weather, clouds, and other environmental factors lead to poor image capture conditions. TerrAvion offers various subscription offerings based on region and crop type. Unlike satellites, however, TerrAvion pilots will work around the weather. TerrAvion pilots operate within one to two-week cycles, so while we try to deliver imagery at consistent intervals, it leaves some room to work around the weather

    Historical imagery.

    TerrAvion also offers a third imagery service: historical imagery. When TerrAvion planes are flying, they are always actively capturing imagery. The unprocessed imagery gets stored in our database and we can process it upon request. If your farm is near one of our other customers, chances are we have historical imagery of your fields and can provide it to you. Historical imagery is valuable information when it comes to build management plans for your field as it can tell you how your fields have performed in previous seasons in far greater detail than yield or soil data. Also in case of an adverse weather events, historical data can proof information for insurance purposes.

    Imagery can help improve every aspect of a growers operations throughout an entire season, but only if the imagery is provided during key agronomic events, for roughly the same cost as a single drone flight, TerrAvion has frequent imagery subscriptions that provide you with the data you need exactly when you need it. Click here to learn more about TerrAvion subscription offerings.

    Imagery turnover time

    Imagery turnover time, the time between image captured until it is delivered to the end user, is a critical component of agricultural imagery services. From the time an image is captured, conditions in that field change, and as they do, the imagery loses its value over time. That's because much of the value of aerial imagery is about indicating how your field is performing at a given time. If you are making management decisions based on imagery, you want to make those decisions based on what's happening in your field right now, not what was happening last month. Timing is crucial for specific imagery applications such as variable rate applications and making harvest timing decisions. TerrAvion has the fastest imagery turnover time in the industry, delivered next day at an average turnover time of 11.2 hours.

    Imagery providers

    Imagery for agriculture is generally going to be captured from an aerial perspective. There are three primary ways that aerial imagery is captured; by satellite, crewed aircraft, or drones.

    Satellite imagery is supplied by various satellites orbiting the earth. Satellite imagery is usually less expensive than imagery captured by drones or crewed aircraft because there is a much lower operational cost. Crewed aircraft and drones require pilots and operators; satellites do not. Satellites offer frequent image deliveries as they are constantly rotating the earth and capturing imagery, but because they are so far away from the earth's surface, the imagery has low-resolution. Satellite image resolution ranges from 50 meters to 1 meter per pixel. In addition, satellite providers do not offer thermal imagery, a key piece of data for farm management.

    Drones are widely used in agriculture and offer the highest resolution imagery out of the three types of providers. Drones are also the most expensive imagery option, significantly more expensive than satellite or crewed aircraft imagery. It takes a drone operator all day to fly the acres that a plane can topa0300-06bcover in less than a minute. After imagery is captured, it doesn't just get sent to the end user; it needs to be processed. Add in these processing costs and the total cost for drone imagery comes in around $5/acre for a single image, making it unrealistic as a weekly or even monthly crop monitoring tool.

    Crewed aircraft offers the high-resolution benefits of drones at a cost more comparable to satellite offerings. The $5 cost of a single drone flight will get you 15 aerial images from TerrAvion at 10-17 cm per pixel. For agriculture, crewed aircraft imagery offers the best deal; high-resolution imagery delivered weekly with the quick turnover time. For more information on how to choose a remote sensing provider, click here.

    How do I view my imagery?

    Most imagery providers will offer a web interface, a mobile interface, or both, where you can view and manage your imagery. Web apps often offer more features to help you manage and act on your imagery, while mobile apps let you take your data on the go while you are scouting your fields. In addition, imagery is available in many farm management platforms and scouting apps, such as those offered by John Deere and Climate. Other programs, while possibly not directly integrated, accept manual imagery imports. TerrAvion offers free highly functional mobile and desktop apps, as well as a long list of integrated partners whose platforms can display our imagery. Many of our integrated partners, like FluroSense and Farm Dog, offer additional features that work flawlessly with TerrAvion data. For more information on the TerrAvion apps, click here. For a list of TerrAvion integrated partners, click here. 

    What can imagery do for me?

    management zones-1Now that you are a little more familiar with the different types of imagery offerings out there let's talk about situations how imagery can help you make more money. Imagery can help you be more efficient in every part of your operations.

    • Imagery data, along with yield and soil data, is extremely valuable information when it comes to building seeding plans for your fields.
    • Imagery helps you identify and address soil moisture, compaction issues, and weed issues.
    • After emergence, monitor your imagery for crop stress related to soil, fertility, pest, disease, or other yield-robbing issues.
    • Real-time aerial imagery is the best indication of how a crop is performing at any given time. Use this information to make input decisions and make NDVI and thermal management zone maps to guide any in season applications. The timely and detailed imagery data ensures inputs are going to the exact places where they are going to be most effective.
    • One of the simplest ways growers can use imagery is to guide their scouting efforts. Traditional random scouting with TerrAvion aerial imageryscouting is inefficient and relies on a certain amount of luck to reveal yield-robbing issues. Monitor your most recent image deliveries to identify areas of stress and direct your scouting efforts to those areas. This guarantees that all of the problem areas in your field that require your attention are being seen while not wasting time scouting the healthy areas of your field that don't require your attention by in-field scouting.
    • NDVI imagery has shown to correlate to crop moisture levels during harvest season. Use imagery to help you harvest your driest fields first while allowing you higher moisture crops more time to dry down.
    • Subscription imagery provides growers with a visual diary of how your field performed throughout the season and how certain factors contributed to that performance. Use this information to assess input performance and to build a profitable management plan for the following year.

    For more information on how to implement an imagery program on your farm, click here.

    If you want to talk to someone to learn more about how TerrAvion image data can you help be more effective, fill in the form below: