How to map and measure Pole and Tower Structures

 
Important: Pole structures such as power lines are difficult to model as they are very thin and tall structures. Besides, this kind of structures is often made of reflective materials, and therefore they often appear white in the images and very few keypoints can be detected on them.

 

There are 2 main possibilities to map pole and / or tower structures:

 

Images taken from above (nadir)

A very high overlap is required (more than 90%). 

If the structure is not fully reconstructed in the rayCloud, it is possible to digitize it by creating polylines and by refining the vertices of the polylines in the images.

 
Information: For more information about how to draw a polyline: 202560309.

Using a fisheye camera may help to capture the images because of the wide field of view of the lens.

 

(Recommended) Images taken from the side (oblique)

It is recommended to fly close to the structure and as flight plan, there are several possibilities:

  • Turning several times around it while changing the altitude, following a spiral.
  • Making several circles around the object at different altitudes.
  • Making several vertical length from the bottom to the top of the structure, at different positions around the object.

In all cases, it is needed to have a very good overlap between images (at least 85% frontal and side overlap).

The camera should have a 45 degree angle pointing to the ground. By pointing the camera to the ground, less sky content is visible on images which make them easier to match and it provides a better model. For more information:

 

Video Example

 

Video Tutorial

 

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