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Preliminary Evaluation of Multibeam Backscatter Consistency through Comparison of Intermediate Processing Results

Authors:
Mashkoor Malik at University of New Hampshire
Mashkoor Malik
Giuseppe Masetti at University of New Hampshire
Giuseppe Masetti
Alexandre Carmelo Gregory Schimel at Norges geologiske undersøkelse
Alexandre Carmelo Gregory Schimel
Marc Roche at FPS Economy
Marc Roche
  • FPS Economy
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Abstract

BSWG meeting
Content uploaded by Giuseppe Masetti
Author content
All content in this area was uploaded by Giuseppe Masetti on May 27, 2019
Content may be subject to copyright.
5/11/2019
1
Project Facilitators:
Mashkoor Malik, NOAA, USA
Giuseppe Masetti, UNH CCOM/JHC, USA
Alexandre Schimel, NIWA, New Zealand
Marc Roche, ECONOMIE, Belgium
Margaret Dolan, NGU, Norway
Julian Le Deunf, SHOM, France
GeoHab 2019 – BSWG meeting
Saint-Petersburg, Russia
BSIP: Backscatter Software Intercomparison Project
Preliminary Evaluation of Multibeam Backscatter Consistency through Comparison of Intermediate Processing Results
Project Collaborators:
SonarScope, IFREMER
FMGT, QPS
HIPS & SIPS, Teledyne CARIS
MB Process, Curtin University, CMST
From observation to explanation
GeoHab 2013
Workshop Multibeam Backscatter
Birth of BSWG!
2013 2014 2015 2016 2017 2018 2019 2020
Significant differences in backscatter products
generated by different software
using the same dataset
Major limitation for users
•Quantitative analysis
•Combining multiple sources
•Time-monitoring of seafloor changes…
GeoHab 2019 - BSWG meeting
BSIP State of progress
5/11/2019
2
From observation to explanation
GeoHab 2013
Workshop Multibeam Backscatter
Birth of BSWG!
BSWG Report
GeoHab 2015
2013 2014 2015 2016 2017 2018 2019 2020
GeoHab 2019 - BSWG meeting
BSIP State of progress
GeoHab 2018 BSWG Meeting
Birth of BISP!
From observation to explanation
GeoHab 2013
Workshop Multibeam Backscatter
Birth of BSWG!
BSWG Report
GeoHab 2015
2013 2014 2015 2016 2017 2018 2019 2020
MGR
Project Facilitators
Mashkoor Malik, NOAA, USA
Giuseppe Masetti, UNH CCOM/JHC, USA
Alexandre Schimel, NIWA, New Zealand
Marc Roche, ECONOMIE, Belgium
Margaret Dolan, NGU, Norway
Julian Le Deunf, SHOM, France
Project Collaborators
SonarScope, IFREMER
FMGT, QPS
HIPS & SIPS, Teledyne CARIS
MB Process, Curtin University, CMST
GeoHab 2019 - BSWG meeting
BSIP State of progress
5/11/2019
3
US Hydro Conference 2019
Preliminary Evaluation of
Multibeam Backscatter
Consistency
through Comparison of
Intermediate Processing
Results
Shallow Survey 2018
A First Step Towards Consistency of
Multibeam Backscatter Estimation
Dedicated paper in progress
Mashkoor M first author
Submission end 2019
From observation to explanation
GeoHab 2013
Workshop Multibeam Backscatter
Birth of BSWG!
BSWG Report
GeoHab 2015
2013 2014 2015 2016 2017 2018 2019 2020
MGR
GeoHab 2018 BSWG Meeting
Birth of BISP!
GeoHab 2019 - BSWG meeting
BSIP State of progress
BSIP → Processing Steps
BL
0
Level “as read from
datagram”
BL
3
Level after all corrections
applied before mosaicking
BSIP requested intermediate levels
(provided by software developers)
Currently produced
results
5/11/2019
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BSIP dataset
Backscatter results provided by different vendors
Software SonarScope FMGT CARIS Curtin
Time stamp Time Ping Time Timestamp Ping Time
Ping # Ping
first ping = 0
Ping Number
First ping = 1
Ping Ping Number
Beam # Beam
first beam = 1
Beam Number Beam Beam Number
Beam location (Lat / Long) Latitude/Longitude Latitude /Longitude Longitude /Latitude Longitude / Latitude
Beam location (E / N) GeoX / GeoY Easting / Northing Easting / Northing Easting / Northing
Beam depth BathyRT Depth Depth
Incidence angle IncidenceAngles True Angle IncidentAngle Incidence Angle
BL
0
BS as read from data files
ReflecKM Backscatter Value BL0 Backscatter value
BL
3
BS after all corrections applied
before mosaicking
ReflecSSc Corr Backscatter Value BL3 Corr Backscatter Value
5/11/2019
5
EM2040 Backscatter
SSc BL
0
SSc BL
3
FMGT BL
0
FMGT BL
3
CARIS BL
0
CARIS BL
3
median
-11.5 dB
-14.9 dB
-17.1 dB
Kwinte reference area
EM710 Backscatter
Carré Renard area
SSc BL
0
SSc BL
3
FMGT BL
0
FMGT BL
3
CARIS BL
0
CARIS BL
3
median
-10.3 dB
-14.6 dB
-19.2 dB
5/11/2019
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EM302 Backscatter
Johnston Atoll
SSc BL
0
SSc BL
3
FMGT BL
0
FMGT BL
3
CARIS BL
0
CARIS BL
3
median
-21.9 dB
-26.2 dB
-26.6 dB
Intermediate processing stages enable further insights
BL
3
- BL
0
(ping – beam geometry)
Different software :
•Provide different results
for both BL
0
and BL
3
•Apply different processing
corrections between BL
0
and BL
3
CARIS FMGT SonarScope
5/11/2019
7
Intermediate processing stages enable further insights
CARIS /
FMGT
FMGT/
Sonar Scope
CARIS /
Sonar Scope
(CARIS BL
3
- CARIS BL
0
) - (FMGT BL
3
- FMGT BL
0
)
(CARIS BL
0
- FMGT BL
0
)
(ping – beam geometry)
Which sources of differences is
most significant, BL
0
or BL
3
?
High significant part of
differences between software
is related to BL
0
Strong dominance of values
below 1 is observed
Absolute ratio
∆BL
3
– BL
0
/∆BL
0
for each software pair
Conclusions
●Intermediate processing stages provides insights into differences
between software outputs
○
Differences in level “as read in the datagrams” BL
0
a surprise
●A variety of processing approaches available
○
Improved tools needed to understand impact of one choice vs. another
●Next steps
○
Round 2 processing in progress to provide other intermediate stages (corrections)
●We need your help !!
○
Users: To demand that results processed by different software should agree with each other
○
Software developers: To work together to implement agreed best practices for backscatter
processing
○
BSWG: To provide a platform to facilitate these discussions
5/11/2019
8
BL0 extraction from snippets to beam average
= the most critical BS processing step
●
Importance of a critical scientific approach!
●
See: “Some Practical recommendations for averaging acoustic
backscatter strength”
GeoHab 2019 contribution
L. Fonseca, X. Lurton, R. Fezzani,
J.-M. Augustin &L. Berger
Green – Seafloor
Black - Seafloor + Noise
Red - Seafloor + Noise + Scatterers
Blue - Fitted-distribution
# of samples
amplitude
The idea is that the Fitted-distribution should, at least in
principle, reveal the Seafloor, and not the Noise neither the
Scatterers
The offset between the histogram
(blue line) and the fitted distribution
(red line) reflects the density of
scatterers.
About the backscatter:
●
Like spaghetti carbonara: everyone
knows what it is but everyone cooks it
in its own way.
●
Small cause, great effect. A few more
shells and the world changes.
5/11/2019
9
Questions ?
Alexandre C. G. Schimel (alexandre.schimel@niwa.co.nz)
Mashkoor Malik (mashkoor.malik@noaa.gov)
Marc Roche (Marc.Roche@economie.fgov.be)
Giuseppe Masetti (gmasetti@ccom.unh.edu)
Margaret Dolan (Margaret.Dolan@ngu.no)
Julian Le Deunf (julian.le.deunf@shom.fr)
Thanks to software developers
References
Fonseca L, Lurton X, Fezzani R, Augustin JM, Berger L 2019. Some Practical recommendations for averaging acoustic backscatter strength.
GeoHab 2019.
Kruss A, Madricardo F, Lorenzetti G, Amos C, Kassem H, Ferrarin C, De Pascalis F, Maicu F, Petrizzo A, Umgiesser G, Zaggia L. 2016. Multibeam
echosounder backscatter variability due to sediment resuspension and environmental dynamics in shallow waters. GeoHab 2016.
Lamarche G, Lurton X. 2017. Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping
sonars. Mar. Geophys. Res. 39:5-22.
Lucieer V, Roche M, Degrendele K, Malik M, Dolan M, Lamarche G. 2017. User expectations for multibeam echo sounders backscatter strength
data-looking back into the future. Mar. Geophys. Res. 39:23-40.
Lurton X, Lamarche G. 2015. Backscatter measurements by seafloor-mapping sonars. Guidelines and recommendations. Retrieved 27th April 2018
from http://geohab.org/wp-content/uploads/2013/02/BWSG-REPORT-MAY2015.pdf.
Roche M, Degrendele K, De Mol L. 2013. Constrains and limitations of multibeam echosounders Backscatter Strength measurements for monitoring
the seabed. Surveyor and geologist point of view. GeoHab 2013.
Roche M, Degrendele K, Vrignaud C, Loyer S, Le Bas T, Augustin J-M, Lurton X. 2018. Control of the repeatability of high frequency multibeam
echosounder backscatter by using natural reference areas. Mar. Geophys. Res. 39: 89-104.
Schimel ACG, Beaudoin J, Parnum IM, Le Bas T, Schmidt V, Gordon K, Ierodiaconou D. 2018. Multibeam sonar backscatter data processing. Mar.
Geophys. Res. 39:121-137.
5/11/2019
10
BSIP → Workflow
Evaluation of Multibeam Backscatter Consistency
through Comparison of Intermediate
Processing Results
BSWG: Majority of users use
SonarScope, FMGT, CARIS SIPS and MB System
Software developers requested to provide processed data
Ref: Malik et al. (2018) Lucieer et al. (2018)
5/11/2019
11
BSIP →Rationale
Ref.: Lurton, X. and Lamarche, G., Backscatter measurements by seafloor
‐
mapping sonars. Guidelines and Recommendations, GeoHAB BSWG, 2015.
5/11/2019
12
BSIP → Original Goals
1.Identify processing stages and intermediate results
2.Identify discrepancies in the processing stages
3.Develop consensus about standard processing chain,
nomenclature and metadata
Diversity in processing approaches
Welcomed as long as end users are clear on what was done and why?
With Proprietary software - This transparency is not available
Effect of each adopted processing method is beyond scope of majority of BS
users
Hence need of a an easy to validate test bench
... As a consequence, a large discrepancy prevails in the results obtained by users working with different MBESs and software tools. This has been pointed out by the work of the GeoHab Backscatter Working Group (Lurton et al., 2015) and was the purpose of a dedicated comparison project (Malik et al., 2019). ...
... Determining these offset values is an important step in the process of comparing the results provided by various MBES systems or post-processing software tools possibly using different definitions for the averaging of backscatter level values. A key point addressed in this paper is that most of this variability, such as observed in Malik et al. (2019) could be explained by the different averaging procedures used by the various post-processing software suites. The main values of b for processing acoustic backscatter are b ¼ 2.0 (snippets with Rayleigh distribution), b ¼ 2.5 (beam-averaged backscatter with lognormal distribution), and b ¼ 3.6 (gridded/mosaicked backscatter with a Gausslike distribution). ...
A statistical approach for analyzing and modeling multibeam echosounder backscatter, including the influence of high-amplitude scatterers
Article
  • Jan 2021
The statistical analysis of acoustic backscatter samples recorded by multibeam echosounders can be a valuable tool for remote seafloor characterization and interpretation. The present paper aims at analyzing the statistics of backscatter data values, both in “raw” status and after various averaging operations, using field data. It is shown that the statistics of the data can be adequately described by a Weibull distribution parametrized by the incidence angle and the level of applied processing: the distribution of the averaged backscatter amplitude, processed according to various schemes, varies from a Rayleigh law for raw data to lognormal and finally to Gaussian distribution after successive averaging operations. Based on these results, some recommendations for the calculation of the mean backscatter strength are presented. Finally, the influence of high-amplitude scatterers in the backscatter probability density function is addressed; a scheme is suggested to separate the contributions of the substrate from the contributions of the scatterers on the statistical distribution of sonar data samples.
View
Multibeam sonar backscatter data processing
Article
Full-text available
  • Jun 2018
  • MAR GEOPHYS RES
Multibeam sonar systems now routinely record seafloor backscatter data, which are processed into backscatter mosaics and angular responses, both of which can assist in identifying seafloor types and morphology. Those data products are obtained from the multibeam sonar raw data files through a sequence of data processing stages that follows a basic plan, but the implementation of which varies greatly between sonar systems and software. In this article, we provide a comprehensive review of this backscatter data processing chain, with a focus on the variability in the possible implementation of each processing stage. Our objective for undertaking this task is twofold: (1) to provide an overview of backscatter data processing for the consideration of the general user and (2) to provide suggestions to multibeam sonar manufacturers, software providers and the operators of these systems and software for eventually reducing the lack of control, uncertainty and variability associated with current data processing implementations and the resulting backscatter data products. One such suggestion is the adoption of a nomenclature for increasingly refined levels of processing, akin to the nomenclature adopted for satellite remote-sensing data deliverables.
View
Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas
Article
Full-text available
  • Jun 2018
  • MAR GEOPHYS RES
The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition and processing parameters. If all these conditions are met, stability check and relative calibration of a system are possible by comparison with the averaged backscatter values for the area. Based on a common multibeam echosounder and sampling campaign completed by available bathymetric and backscatter time series, the suitability as a backscatter reference area of three different candidates was evaluated. Two among them, Carré Renard and Kwinte, prove to be excellent choices, while the third one, Western Solent, lacks sufficient data over time, but remains a valuable candidate. The case studies and the available backscatter data on these areas prove the applicability of this method. The expansion of the number of commonly used reference areas and the growth of the number of multibeam echosounder controlled thereon could greatly contribute to the further development of quantitative applications based on multibeam echosounder backscatter measurements.
View
User expectations for multibeam echo sounders backscatter strength data-looking back into the future
Article
Full-text available
  • Jun 2018
  • MAR GEOPHYS RES
With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing capabilities, navigation, and graphic display devices, have improved the resolution and particularly the dynamic range available to sonar and processing software manufacturers. Alongside these improvements the expectations of what the data can deliver has also grown. In this paper, we identify these user-expectations and explore how MBES backscatter is utilized by different communities involved in marine seabed research at present, and the aspirations that these communities have for the data in the future. The results presented here are based on a user survey conducted by the GeoHab (Marine Geological and Biological Habitat Mapping) association. This paper summarises the different processing procedures employed to extract useful information from MBES backscatter data and the various intentions for which the user community collect the data. We show how a range of backscatter output products are generated from the different processing procedures, and how these results are taken up by different scientific disciplines, and also identify common constraints in handling MBES BS data. Finally, we outline our expectations for the future of this unique and important data source for seafloor mapping and characterisation.
View
Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars
Article
Full-text available
  • Jun 2018
  • MAR GEOPHYS RES
Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group (Geohab.org) has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working group, and a synopsis of the BSWG Guidelines and Recommendations to date. The paper includes (1) an overview of the current status in sensors and techniques available in seafloor backscatter data from multibeam sonars; (2) the presentation of the BSWG structure and results; (3) recommendations to operators, end-users, sonar manufacturers, and software developers using sonar backscatter for seafloor-mapping applications, for best practice methods and approaches for data acquisition and processing; and (4) a discussion on the development needs for future systems and data processing. We propose for the first time a nomenclature of backscatter processing levels that affords a means to accurately and efficiently describe the data processing status, and to facilitate comparisons of final products from various origins.
View
View
Schimel (alexandre.schimel@niwa.co.nz) Mashkoor Malik (mashkoor.malik@noaa.gov)
  • C G Alexandre
Alexandre C. G. Schimel (alexandre.schimel@niwa.co.nz) Mashkoor Malik (mashkoor.malik@noaa.gov)
Some Practical recommendations for averaging acoustic backscatter strength
  • Jan 2019
  • L Fonseca
  • X Lurton
  • R Fezzani
  • J M Augustin
  • L Berger
Fonseca L, Lurton X, Fezzani R, Augustin JM, Berger L 2019. Some Practical recommendations for averaging acoustic backscatter strength. GeoHab 2019.
Multibeam echosounder backscatter variability due to sediment resuspension and environmental dynamics in shallow waters
  • Jan 2016
  • A Kruss
  • F Madricardo
  • G Lorenzetti
  • C Amos
  • H Kassem
  • C Ferrarin
  • De Pascalis
  • F Maicu
  • F Petrizzo
  • A Umgiesser
  • G Zaggia
Kruss A, Madricardo F, Lorenzetti G, Amos C, Kassem H, Ferrarin C, De Pascalis F, Maicu F, Petrizzo A, Umgiesser G, Zaggia L. 2016. Multibeam echosounder backscatter variability due to sediment resuspension and environmental dynamics in shallow waters. GeoHab 2016.
Constrains and limitations of multibeam echosounders Backscatter Strength measurements for monitoring the seabed. Surveyor and geologist point of view
  • Jan 2013
  • M Roche
  • K Degrendele
  • De Mol
Roche M, Degrendele K, De Mol L. 2013. Constrains and limitations of multibeam echosounders Backscatter Strength measurements for monitoring the seabed. Surveyor and geologist point of view. GeoHab 2013.