Sunday, 27 October 2024

Practising with the Forestry Pro 2

 After completing the tree measuring exercise for the Forestry Commission Felling Licence I thought it would be sensible to double check some of the tree hright measurements. I took the Nikon Forestry Pro 2 to the orchard with a spreadsheet printout of the Ash trees.  Most of the leaves have now fallen so I can more easily see the tops of the trees from the limited confines of the orchard.


The Forestry Pro 2 works by measuring the time it takes for a brief pulse of near-infrared laser light to bounce back from the target object. In that respect, it is a bit like a radar.It can measure distance with an accurance of a cm or two over a distance of 100 metres, its full range is about 1500 metres depending on conditions. There is also an in-built clinometer which measures the angle you are tilting the device at the time the reading is taken.By performing trigonometry on the readings the device can calculate:

  • Distance of object
  • Angle of the object, from horizontal
  • The horizontal distance
  • The height of the top of the object.
For height measurement you have to trigger the tool whilst sighting on the bottom and then on the top of the object, such as a tree. This is called the two point mode.  There's a three point mode where you first measure the horizontal distance, then aim it at where the top is and then at the base of the object (tree); this works even if you can't see the top/bottom of the tree. The caclulation is completed in less than a second and displayed on an LED screen inside and outside of the Pro 2.

With the sample I checked, my earlier height estimates were reasonably accurate compared to the readings I obtained.

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