How to to create Targeted Spraying Prescription Maps | [PIX4Dfields/QGIS] Tutorials

In this video tutorial we demonstrate how you can use a vegetation index processed in PIX4Dfields to create a targeted spraying prescription map in QGIS. Those maps can be used to selectively apply for example herbicides only to areas with weeds. You can use the map for boom sprayers as well as for spray drones.

You can download a written description of the workflow.

Let us know what you think and comment if you would like to see a QGIS model simplifying the complete workflow with just a few clicks.

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I’m a little late and this is probably obsolete with the release of V2.4, but thankyou for this.

Related, is there a workflow to import GPX waypoints to a prescription generation? I’d like to mark weed areas with a handheld GPS throughout the season so I can come back to them with a drone at the right time. I can easily get the GPX data from the GPS and it provides a painless and economical way for staff to also tag problems whenever they see them.

Cheers,
Pete

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Hi Peter,

your use case is still valid and with the current release of 2.4 Targeted Operations you could solve it. But it needs some preprocessing of your GPX data before you can import them. For that I would recommend you the free and open-source software QGIS:

Here are the steps:

  1. Importing the GPX file:

    • Open QGIS.
    • Go to Layer → Add Layer → Add Vector Layer.
    • In the “Source” panel, click on “Browse”.
    • Navigate to your GPX file, select it, and click “Open”.
    • Click “Add” in the “Data Source Manager” window.
    • Close the “Data Source Manager” window. Your GPX waypoints should now be visible on the map.
  2. Converting waypoints to a multipolygon shapefile using the buffer tool:

    • Go to Vector → Geoprocessing Tools → Buffer.
    • In the “Buffer” window, select the name of your GPX layer in the “Input layer” dropdown.
    • Set your desired buffer distance in the “Distance” field. The unit of the distance depends on the coordinate system of your data. If your map is in a geographic coordinate system (latitude/longitude), the distance will be in degrees. If your map is in a projected coordinate system (like UTM), the distance will be in meters.
    • Click “Run”. This will create a new layer with your buffered waypoints.
  3. Merging the buffered areas into a single multipolygon:

    • Go to Vector → Geoprocessing Tools → Dissolve.
    • In the “Dissolve” window, select the name of your buffered layer in the “Input layer” dropdown.
    • Click “Run”. This will create a new layer with your buffered waypoints merged into a single multipolygon.
  4. Exporting the result as a shapefile:

    • Right-click on the name of your multipolygon layer in the “Layers” panel.
    • Click “Export” → “Save Features As…”.
    • In the “Save Vector Layer As” window, select “ESRI Shapefile” in the “Format” dropdown.
    • Click “Browse” next to the “File name” field, navigate to your desired save location, enter a name for your shapefile, and click “Save”.
    • Click “OK”. Your multipolygon shapefile should now be saved to your chosen location.
  5. Import the shapefile as annotations in PIX4Dfields:

  • Select a layer where you want to import your shapefile like an orthomosaic or index
  • On the right sidebar “Annotations” select “Import geometry or images” to import your shapefile as annotations
  1. Use your imported annotations for Targeted Operations

I hope that helps!

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I’ll have a go with your steps tonight. At first glance that looks fantastic for what I’m trying to achieve.

Thankyou

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G’day Julius, I followed your detailed steps and imported shapefiles successfully, thankyou.

After loading the missions to a T40, I have some thoughts that I hadn’t considered initially;

Care needs to be taken to generate individual spots that are large enough for the spray platform to process. In my case the T40 won’t accept shapes that are ~1M in diameter. I realise the T40 can’t physically spray within such a small target, but the T40 mission planner simply won’t recognise the shapes at all. I haven’t experimented yet to see what the actual minimum size is.

More importantly though, the shapefiles import as a separate mission for each shapefile. This is completely unworkable as I’m expecting dozens of 2 square meter targets in a field. The goal is for the T40 to treat the mission as an orchard mission where the drone calculates the most efficient route to spray just the targets. Flying AB lines across the entire field when there is less than 2% actual target is a massive waste of time and defeats the purpose.

Regards,
Pete

Currently as a 3rd Party we are limited to the AB line application style, as DJI did not open the path planning for their Agricultural drones yet. So what we can solve is to save inputs but not necessarily flying time of the drone.

Could you send us a screenshot of your project, maybe we can think about a smarter way together :slightly_smiling_face:

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G’day Julius,

I’m waiting for hardware to come back to me so I can investigate further. Hoping to get back onto this in the next couple of weeks.

Regards,
Pete

Buenas tardes. Instale la versión 3.16.16 del QGIS y en los complementos no me aparece la opción de agregar “ZONAL STATISTIC FOR MULTIBAND RASTERS”, por lo que no puedo avanzar mas con el proyecto.

Hola,

En nuestra proxima version PIX4Dfields 2.5, podrá realizar todo el trabajo con la nueva herramienta de zonificación.

Este atento
José