What is the correct resolution for my laser scanner?

Here, the principle is: Don’t scan as detailed as possible but as detailed as necessary!

The graticule

In order to make the correct choice, we want to explain the basic principles.
The laser scanner transmits a laser signal that is reflected by the object. Within the process, the room/object is scanned automatically and successively by the laser. Thus, a graticule is generated that is determined by the angular step size (horizontal and vertical circle) and the distance from the scanner to the object (intercept theorem). The lower the selected resolution, the bigger the angle between the single measured points of the laser scanner. Consequently, the distance between the single measured points is higher.

resolution settings laser scanner

resolution settings laser scanner

resolution settings

resolution settings laser scanner

resolution settings laser scanner

laser scanner resolution settings

Distance between measured points

In figure 1 and 2, we show how the distance between scanner and object affects the distance between the measured points.

The distance between two measured points increases with the distance to the measured object.

Steps for changing settings in FARO Focus 3D

Settings FARO Focus 3D

Settings FARO Focus 3D

Examples by reference to FARO Focus 3D

Resolution Quality Scan time in min No. of points in million Point distance in mm/10m distance
1/32 4x 2:03 0,7 49,087
1/20 4x 2:14 1,7 30,680
1/16 4x 2:23 2,7 24,544
1/10 4x 3:05 7,0 15,340
1/8 4x 3:44 10,9 12,272
1/5 4x 6:31 28,0 7,670
1/4 4x 9:06 43,7 6,136
1/2 4x 30:34 174,8 3,068
1/1 2x 30:34 699,1 1,534

The chart shows how the resolution affects time and point distance. That’s why it is very important to reflect about the optimum resolution for your project.

The following images of a scan cloud give you an idea of the various resolutions.

Overview of scan resolutions

Scan with 1/20 with quad quality in a distance of 7m

1_20_4x_1

Scan with 1/10 with quad quality in a distance of 7m

1_10_4x_1

Scan with 1/5 with quad quality in a distance of 7m

1_5_4x_1

Scan with 1/2 with quad quality in a distance of 7m

1_2_4x_1_0

Summary – Correct resolution for your laser scanner

In order to decide for the perfect scanner resolution, it is important to keep sight of the definition of task. Finally, laser scanning has to be economic. That is only guaranteed when the ideal parameters are chosen. You should pose the following questions:

Is it outdoors or indoors?
How big are the distances between scanner and object?
How many scans will I do in order to avoid shadowing?
Do I need colored point clouds or is a grey point cloud even more informative?
How do I process scan data and with which software can I do this?

The longer the distance to the object, the higher the resolution has to be. For a house facade with brick slip cladding without any decoration, for instance, a resolution of 1/4 and dual quality would suffice. But it is more important to avoid shadowing by using many laser scanner positions.

Please take notice of our article: True Laser Scanning /01 – How Do I Position a Laser Scanner to Scan a Façade?

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