The Influence Of Surfaces On The Measurement; Wet Or Shiny Surfaces - Hilti PD-C Manual De Instrucciones Original

around a single, unchanged starting point. On the other hand, rotating the tool without using a measuring
extension or a tripod will often cause slight deviation from the exact reference position.
The measuring accuracy when using the 'Measure from picture' function depends on whether the tool is
positioned at an exact angle of 90° to the target (at both horizontal and vertical right angles) and on whether
the whole surface surveyed in the target picture is genuinely level, such as a façade or a ceiling. The following
table shows the typical deviations for measurements in photos when the photo was not taken from a 90° angle.
Errors caused by surveying from a position not at right angles to the wall
The following table presupposes that the vertical 90° angle against the wall is maintained using the inclination
indicator on the range meter.
The data on error percentages in the table estimates the deviation of the measurement in relation to the
corresponding real distance.
Limitations
• Individual adjustment of tools is not taken into account.
• Values apply to freehand measurements.
• If a tripod is used, the accuracy is increased by approximately 0.5%.
•/•
Deviation from the
horizontal 90° angle
against the wall
0°
maximum ±3°
3.12.1 'Measure from picture' for advanced users
If the procedure is carried out with due care, aiming the laser at a horizontal or vertical line at a 90° angle
allows advanced users to use the 'Measure from picture' function to determine a distance along the line.
This method must be used with caution, as all of the distances determined in the picture that do not lie along
a line surveyed at a 90° angle will be significantly less accurate.

3.12.2 The influence of surfaces on the measurement

The Hilti laser module, developed on the basis of PulsePower (millions of pulses per second), offers the best
conditions for reception of an ample number of distinct samples of reflected laser light, which are used to
calculate precise measurements.
However, there are situations in which the tool will not receive a sufficient amount of reflected light from
the target. Understanding this principle means that certain remedies are possible, such as the use of target
plates from Hilti, available as an accessory. Use of target plates allows a substantially larger amount of light
to be reflected from the target to the tool.
Examples of situations where an insufficient amount of light is reflected include missed targets (e.g. a laser
beam that misses the ceiling and is instead aimed at the sky), luminous, non-reflective surfaces, obstructions
such as mist, rain or dust between the tool and the target, non-reflective dark surfaces or surfaces with a
velvety structure, materials that absorb light, such as foam, or rough surfaces.
3.12.2.1 Rough surfaces
When measuring to rough surfaces, such as rough plaster, an average distance value is established with the
center of the laser spot weighted higher than the edges of the laser spot.
3.12.2.2 Curved or inclined surfaces
If the laser beam strikes the target surface at a very narrow angle, the light reflected may be inadequate.
Conversely, too much light may be reflected toward the tool in situations where the laser beam strikes the
target perpendicularly. We recommend use of a target plate (PDA 50, PDA 51 or PDA 52) in both of these
situations.

3.12.2.3 Wet or shiny surfaces

A still, calm pond reflects both the clouds and light from the sky. A shiny, wet surface reflects the laser light
in a similar way. If the targeted surface is wet and shiny, it is important that the measurement is taken at right
angles, as far as possible, as otherwise the light will be reflected in a different direction and too little light will
return to the tool to calculate a measurement.
Length of the line drawn on the screen in relation to the width of the
< 30%
±4.5%
±5.2%
screen (without zoom)
30% to 50%
±2.5%
±3.7%
> 50% to 100%
±2.2%
±4.9%
47