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The primary reason is to get an indication of how airflow within a clamp may change over a storage period. If a clamp decreases in size, it could come from one (or both) of two places – the beet fraction, or the air fraction. If it is the air fraction, then bulk porosity and thus permeability would decrease. If it is the beet fraction that has decreased in size, then it is likely that the bulk porosity won’t change much, but that the permeability will still decrease with a decrease in pore size.

3D image of sugar beet clamps built using drone images


Drones (RGB camera) + appropriate software. Flying over the same clamps at different periods will capture the necessary data. Processing the images is of just now a little less certain, but not a barrier. The options that are known include:

  • SOLVI – we will have this software, but it doesn’t explicitly measure volume. What it can do is measure distances and heights. So with a well marked out clamp and one or two assumption about clamp shape, we can measure volume.
  • DJI Terra – this does measure volume, but it is uncertain if we will have access. If we do have access, this is the option we will take as it is very easy to use.

In terms of sampling, I could see something like:

  • no less than 2 clamps. (maybe a student could take two, NBR two)
  • sample a 20m length per clamp, marked every 1m to allow for accurate image processing.
  • sample using the same mission every time. I think Pix4DCapture will be suitable for this.
  • sample on day of construction, one week after, and just prior to delivery. It will also be important to sample before and after any changes in covering to capture the change in surface smoothness. So, it is likely sampling will be needed at least twice between the “one week after construction” and “delivery” sampling points.

This procedure results in a total of five samples per clamp, on four clamps = 20 samples = 20 images to process = a bit of work. Only having two clamps would make this an easy side project.


Mid to late November through to late January/ early Feb. This should be manageable during the 2021 campaign.


Setup at each clamp will take a couple of hours, with each subsequent flight being 30 minutes work, plus travel. Drones are owned, as too the software. If the clamps are in walking distance around Alnarp and Borgeby, then the cost will be nothing but time. If the clamps are part of a ventilation trial, then travel will be necessary (probably only around 4 mil per flight). External funding might be nice to pay for the better DJI Terra software, if it’s not available through SLU (ca. 12 000 SEK).


NBR wants it, so it will happen. Whether a student joins or not is the question.


This would be a great student project, and one we could probably do without external funding.

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