How to map and measure Pole and Tower Structures - PIX4Dmapper

This article provides two possibilities to map and measure pole and tower structures, with oblique (recommended) and nadir images.

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

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

(Recommended) Images taken from the side (oblique)
Images taken from above (nadir)

(Recommended) Images taken from the side (oblique)

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

Turning several times around the object of interest while changing the altitude, following a spiral.
Making several circles around the object at different altitudes.
Making several vertical lengths 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 in images, which makes them easier to match and provides a better model. For more information:

Video Example
Video Tutorial

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: Please refer to this article on how to draw a polyline: How to draw a Polyline in the rayCloud.

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

Video Example

Video Tutorial