Experiences from the post processing of typical Finnish bathymetric data Jarmo Ahonen Shallow Survey 2008 Portsmouth, NH

Agenda Survey vessels and survey environment Workflow Examples Qinsy Qlucheck Fledermaus CUBE S2Edit Examples Conclusions from our experiences

Multibeam vessels M620, M640, Kaiku (SB 8101) Suunta (SB 8111) Airisto, M249 (SB 7125) M620, M640, Kaiku (SB 8101) Suunta (SB 8111)

Single beam vessels M145, M146, M148, M247 (NS 2000) Kieku 2 (NS 110)

Mother ship Saaristo

”The most beautiful archipelago in the world” ”The land of the thousands of lakes”

Agenda Survey vessels and survey environment Workflow Examples Qinsy Qlucheck Fledermaus CUBE S2Edit Examples Conclusions from our experiences

Workflow Validator Qinsy Online Analyzer Processing Manager Qlucheck db qpd Analyzer heading/pitch/roll/heave positioning Processing Manager SVP Tide ASCII export Validator depth blocking sector blocking .db .qpd Qlucheck ASCII to FAU .fau S2 Software Contouring Area based analysis/cleaning Data thinning Fledermaus Area Based Cleaning CUBE Unload to fau Qlucheck 15/50 million points/block .fau .fau .s2d Orderer = FMA

QINSy Online .db, .qpd QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Analyzer Check the motion sensor data and positioning if notice in the logbook QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Processing Manager Applying Tide and SVP QINSy Online Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Validator Points flagged by Depth and Sector blocking are not in the next post processing steps Limiting opening angle to avoid bad data QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Processing Manager Export user defined ASCII Easting, Northing, Depth, Ping ID, Beam ID, Quality 1467111.420 6614994.110 -37.05 1 43 11 1467111.840 6614994.180 -37.05 1 44 15 QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Qlucheck FMA software Format converter ASCII to FAU Quality value is needed in importing to Fledermaus brightness and collinearity flags Ping ID and Beam ID is needed in splitting the FAU files QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Fledermaus Custom filters CUBE parameters Brightness and collinearity flagged points are set to rejected in import CUBE parameters Bin size: 1 m Capture Distance: 5 % of depth Hypothesis resolution algorithm: Number of Samples + Neighborhood Calculate errors using sensor specific error model Area based editing Clean the outliers first QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Shallow edited surface A lot of spikes in the data QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

CUBE edited surface Still some spikes in the data Selected area in focus in 3D Editor QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

<= Set hypothesis to shallowest points <= Points colored by survey lines Points and hypothesis => <= Set hypothesis to shallowest points QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

<= Unedited CUBE surface <= Raw data <= Unedited CUBE surface Hypothesis set to shallowest points => QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

CUBE Filter Filter soundings based on CUBE surface 4x standard deviation QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Qlucheck Split FAU files .S2D file size limit 50 (15) million points QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

S2Edit FMA software Are based editing in 2D/3D Contour view in 2D/3D Lasso tool Contour view in 2D/3D Point view in 2D/3D Swath view in 2D/3D DTM model view in 2D/3D Numerical view in 2D/3D QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Depth contours give an indication where to focus Min and max values in 3D Depth contours give an indication where to focus QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Colored by survey lines Easy to see typical outliers like aquatic vegetation, sonar errors, fishes Overlap areas Colored by survey lines QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Depth contour view Swath view Numerical view check the suspicious targets check the shallowest areas Swath view check if the target is in the overlapping area Numerical view take a closer look QINSy Online Processing Manager Validator Analyzer Qlucheck Fledermaus Qlucheck S2Edit

Agenda Survey vessels and survey environment Workflow Examples Qinsy Qlucheck Fledermaus CUBE S2Edit Examples Conclusions from our experiences

Example 1 Outliers cleaned before CUBE filter (4x std dev.) Contours are smooth Swath view shows that CUBE filter succeeded

Example 2 Outliers not cleaned before CUBE filter (4x std dev.) Contours are mainly smooth Outlier contours inside the boxes Clear outliers still exists

Example 2 SB7125 produces a lot of outliers Outliers should be cleaned before CUBE filtering

Example 3 Shallowest points in the region are the most important points Blue point is shallowest and accepted Red points are rejected CUBE filters also points which are real sea bed FMA does not accept this

Conclusions Every post processing software has pros and cons There are no automatic algorithms that can clean challenging sea beds satisfyingly in Finnish environment SB7125 produces a lot of data and a lot of outliers CUBE reduces manual editing CUBE works better in relatively flat sea bottoms Good work in the survey situation significantly reduces the post processing work

Agenda Survey vessels and survey environment Workflow Examples Qinsy Qlucheck Fledermaus CUBE S2Edit Examples Conclusions from our experiences

Thank you! M.Sc. Jarmo Ahonen jarmo.ahonen@fma.fi