Airborne Laser Scanning Software

RiMTA

for Automated Resolution of Range Ambiguities••automatic resolution of range
ambiguity in time-of-flight ranging

Acquiring data in airborne laser scanning with high measurement rates from high altitudes frequently results inrange ambiguities. Instruments with multiple-time-aroundcapability (MTA) like the LMS-Q680i provide data that canbe utilized to resolve these ambiguities in post-processing.
Instead of manually specifying the correct MTA zone forrange calculation, RiMTA will detect the correct MTA zone
for each measurement automatically.

••unlimited number of MTA zones••processes data acquired withRIEGL VQ-580 and RIEGL LMS-Q680
laser scanners

Correctly determining a measurement range in LIDAR instru-••smoothly integrated in theRIEGL data processing workflow

its causative emitted laser pulse. However, at high pulse repe-ments, based on time-of-flight measurements with short laser
pulses, requires the allocation of each received echo pulse totition rates (PRR) and large measurement ranges this definite
allocation becomes ambiguous due to a limiting factor whichmay not be tweaked by engineers‘ skills: the speed of light. Ata PRR of 400 kHz the range of unambiguity is already left at
ranges above only approximately 375 meters, a measurement
distance which is easily exceeded in airborne laser scanning(ALS).
The loss of unambiguity in ranging is known as“multiple-time-around” or “multiple-pulses-in-theair”. Up to now it was necessary to carefully avoid
the appearance of range ambiguities during flightplanning by choosing a height above groundfor data acquisition so that all measurements
stay within a single MTA zone, a task which becomes exceedingly difficult especially in complex terrain like, e.g., mountainous areas.

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Ri Software

Preliminary Datasheet

RiMTA - For Automated Range Ambiguity Resolution
A novel approach based on the application of a sophisticated modulation scheme to the train of emitted laser
pulses and on a dedicated data processing algorithm,
allows the correct resolution of range ambiguities without
any information about the expected measurement ranges
and does not require any user-interaction.
WithRIEGL’s

airborne

laserscannersVQ-580

andLMS-Q680i, which are easily capable to measure up toMTA zone 4, i.e., having up to 4 consecutive laser shots
and the corresponding multiple echo signals in the air at
the same time, this technique is a vast improvement when
Profile of scan data processed in
MTA zones 1 to 4

conducting airborne scanning surveys. It especially relaxes
the requirements in flight planning for mountainous regions, thusincreasing flight safety. The subsequent data processing with RiMTA
is smoothly integrated in RIEGL’s workflow for scan data processing
using RiPROCESS.

One scan stripe transitting
three MTA zones:yellow
MTA 1blue
MTA 2
purple MTA 3

Flight altitude above ground level descentfrom 1,000 m to 200 m
MTA 1

MTA 3
MTA 2

RIEGL Laser Measurement Systems GmbH, 3580 Horn, Austria
Tel.: +43-2982-4211, Fax: +43-2982-4210, E-mail: office@riegl.co.at
RIEGL USA Inc., Orlando, Florida 32819, USA
Tel.: +1-407-248-9927, Fax: +1-407-248-2636, E-mail: info@rieglusa.com
RIEGL Japan Ltd., Tokyo 1640013, Japan
Tel.: +81-3-3382-7340, Fax: +81-3-3382-5843, E-mail: info@riegl-japan.co.jp

www.riegl.com
Information contained herein is believed to be accurate and reliable. However, no responsibility
is assumed by RIEGL for its use. Technical data are subject to change without notice.

Preliminary data sheet, RiMTA, 26/09/2011