What are targets and why are they important in a laser scanner survey?

November 6, 2022

A good one laser scanner survey cannot rely only on quality equipment. In fact, it is necessary to start from a strategic planning of all the phases of the survey, which also includes the positioning of laser scanner tools and targets.

What are targets in a laser scanner survey and what are they used for?

What are laser scanner targets?

THE laser scanner targets or markers They are accessories that support the survey instrumentation, which allow the scan to be recorded and carried out more efficiently, acting as reference points on the territory.

They are used in particular in laser scanner scans of external areas and ensure high precision, especially when it comes to merge the results of multiple scans.

The targets must be:

Highly visible from the laser scanner;
Easily adaptable to the characteristics of the terrain;
Easy to place and to remove.

There are two types of targets:

Naturals, or particular elements that are easily recognizable during scanning such as edges or doors;
Artificial, reflective accessories at the wavelength of the laser scanner. Artificial targets

There are different types of artificial laser scanner targets, let's see what they are.

1. Flat or paper targets

These are the Most used targets, typically square but also circular in shape, and are placed on the ground or fixed to a surface. They are made with two colors arranged in a checkerboard pattern to be visible to scanners and are the cheaper, especially paper ones that can be printed.

The important thing when printing paper targets is do not use an inkjet printer, otherwise there is a risk that the laser will not see the different colors and will make an inaccurate scan.

2. Spherical targets

Spherical laser scanner markers are the more practical to use, because their shape makes them easier to position and makes scanning more effective from any direction.

Generally they are painted with a specific reflective white paint and can be equipped with either a support or a magnetic base, which is more modern and practical.

3. Targets marked with ID

THE target with ID They can be either flat, paper-based or spherical and are equipped with different and unique numbers and matrices.

Having targets marked with an ID allows you to work more easily even in particular situations, as in the presence of several geometrically similar elements (columns, windows, etc.), or in narrow spaces.

In fact, IDs allow the point clouds obtained from different scans of hook up with each other to obtain a complete survey and point cloud of the necessary data.

How to use targets and markers for laser scanner surveying

Laser markers allow you to create points that are easily recognized by the laser scanner. Using them takes longer to scan, but simplifies data acquisition and allows for faster and more efficient registration work.

It is important though know how to use these accessories to perform correct scans.

First of all it is important to buy or make them in specific materials, neither shiny nor transparent, and above all position the targets correctly, which may otherwise lead to an incorrect scan of the territory.
Each area to be scanned also has specific characteristics and for this reason they must be use different techniques, the advice is therefore to have multiple types of laser scanner markers and targets available during a survey to be able to use the best ones in every situation.