Sorghum in peanuts (Green on Green) - PIX4Dfields

PIX4Dfields supports green-on-green detection through high-resolution imagery and the Magic Tool. Follow this article to learn how to detect Sorghum alepense in Peanuts.

Introduction

Green-on-green detection in agriculture allows for identifying weeds among crops, which allows spot-spraying and minimizes blanket herbicide applications. By targeting only the affected areas, this method not only reduces herbicide costs but also minimizes environmental impact.

GSD Requirements

The provided data has 1.8 cm GSD. Orthomosaics with a GSD between 0.5 and 3 cm are ideal for detailed, plant-level weed detection. This ensures high-resolution detection of individual weeds within crop canopies.
If weeds occur in larger patches or zones, a lower resolution of GSD between 4 and 8 cm is generally acceptable.

Peanuts infested with Sorghum alepense

Orthomosaic size	3.2 GB
Average Ground Sampling Distance (GSD)	1.8 cm / 0.78 in.
Area covered	35 ha / 79 acres.
Image acquisition plan	1 flight, grid flight plan.
Drone and camera	DJI Mavic 3 Enterprise RGB camera
Reflectance panel/target	Not applicable
Fill out the form to receive the example orthomosaic

Download and import Orthomosaic to PIX4Dfields

Download the example layer "Sorghum&Peanuts.tif" and import it into PIX4Dfields:

1. On the dashboard, click + New Project or the + symbol at the bottom right corner of the window.
   
2. A new window with a background satellite image appears.
3. Click the pen symbol beside the default name of the project to rename the project.
4. Under Other map, click GeoTIFF.
   
5. Select the example file "Sorghum&Peanuts.tif" and click Open.
6. The Orthomosaic is imported successfully.

Detecting weeds with the Magic Tool

Create a boundary: 

1. Click theBoundaries layer on the left board above the layer list to enter the boundaries mode.
2. To draw a field boundary, click the Draw boundary icon in the left corner of the map.
3. Select Boundary. Note that obstacles can be created as well.

1. 1. Left-click to start drawing.
   2. For more information: Field boundaries and obstacles - PIX4Dfields.

Access the tool by clicking the Magic icon next to the Index icon.

1. Select the Layer and Boundary.
2. Set the Cell Size
   The GSD influences the minimum cell size. A very small cell can degrade selection performance. In this case, set it to 2 meters.
3. Add Sorghum and click next.
4. Labeling
   Manually identify areas of weeds and crops by clicking on them within the boundary:
   1. Weeds: Click Wanted and click on at least 6 cells representing weed areas. (blue)
   2. Crops: Click Not wanted and click on at least 6 cells representing crop areas. (yellow)
   3. Purpose: These sample points help the Magic Tool distinguish weeds from crops based on visual patterns and color differences
5. Clean up 
   In Step 5, clean up the selection manually and add or delete cells. Incorporate a buffer by selecting the + icon; this will help ensure that the surrounding areas of the weed nests are effectively treated during the spraying process.
   
6. Convert the results into an operation layer. This step completes the weed detection process, resulting in an operational layer that provides valuable insights for targeted herbicide applications or additional analysis.