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SIRDAS.Net. Introduction to SIRDAS.Net Slides for workshop with Statkraft March 10, 2011. http://www.albrektsen.net/sirdas. Espen Halsaa Albrektsen [email protected] Agenda. Getting started Installation What is SIRDAS.Net Basic operation Opening a file

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Sirdas net

SIRDAS.Net

Introduction to SIRDAS.Net

Slides for workshop with StatkraftMarch 10, 2011

http://www.albrektsen.net/sirdas

Espen Halsaa [email protected]


Agenda

Agenda

  • Gettingstarted

    • Installation

    • What is SIRDAS.Net

  • Basic operation

    • Opening a file

    • Depth Reference measurements

    • SnowDensitymeasurements

    • Data export

  • Advanced operation

    • Manual routecorrection

    • Data analysis tuning

      • Vertical filters

      • Horizontal filters

      • Routefinder


Getting started

Gettingstarted

  • Download and installSIRDAS.Net from

    • http://www.albrektsen.net/sirdas

    • Youneedsome Microsoft tools – thesearedownloadedautomatically if not allreadyinstalled on your system

  • Start theapplication, and request a license key

    • A request is posted to my web site – I manuallygenerate a license key and email back to you.(Expect 1-3 bussinessdaysdelay)

  • Start theapplication, and register thelicense key

  • Start theapplication – youaregood to go! 


Basic operation

Basic Operation

  • SIRDAS.Net supports theNogginPlus file format

    • Eachscanconsistsof 3 files, with file types ‘.dt1’, ‘.hd’ and ‘.gps’. Thesethree files must be in the same directory and have the same filename:

    • When a .dt1 file is selected for analysis, SIRDAS.Netimmediately starts processingthe file data.

    • If theNogginPlus file containsreference points (Fiducial Markers in theNogginPlus manual). SIRDAS.Netassumesthat a NogginPlusFiducial Marker is a manual depthmeasurement, and allowstheuser to enterthisinformation.


Plot navigation

Plot navigation

  • Mouse wheel is supported

    • Ctrl+wheel zooms in and out

    • Wheel pans left and right (Afteryou have zoomed)

  • Zoom out

    • Press ESC key

    • By usingthemousewheel

    • By pressing the zoom outbutton:

  • Zoom in

    • By selecting a range

  • Pan

    • By mouse or keyboard.

    • Ctrl-arrowmoves to start or end


Depth references

Depth References

Used to calibratewavepropagationvelocity, and to toadjust for equipment-specificdepth offset


Purpose

Purpose

  • Used to calibratetheconversionbetween sample index and depth.

    • Averagewavevelocitydefaults to 0.2m/ns

    • The radar signal is sampled at a fixedinterval (samplerate) – a sampleindex is therefore a representationofthetwo-way travel time from radar to ground and back

  • The wavevelocityvarieswithsnowdensity and needs to be calibrated

  • Zero-level

    • Zero-level is initialized to thevaluecalculated by theCut-off-filter. (See filter section for details)

  • The zero-level offset depends on equipment and alsoneeds to be calibrated.

  • Zero-levelcan be updatedmanually, or reference points for zero levelcan be entered.


Depth reference form

Depth Reference Form

RouteSampleIndex is updatedonce a aroute is found

ShotIndex is thepositionofthis Depth reference

WaveVelocity for thisshot

Averagewavevelocity

Depth is manuallyentered by theuser

Sample index for zero depth


Depth reference form1

Depth Reference Form


Depth reference form2

Depth Reference Form

Reference point is plotted at «correct» depth and position

Zero-level offset clearly visible in graph


Zero level index

Zero-levelindex

  • Initialized by analyzingtheaverage energy in the first 100 samples of all shots:

  • Manual overrideeither

    • By entering a depthreferenceof zero meters

    • Or by adjusting zero sample indexdirectly


Snow density observations

SnowDensityObservations

Used to calibratetheformula for convertingsnowdepth to snow-water equivalent (SWE)


Snow density measurements

SnowDensityMeasurements

  • Is used to calculatethesnow-water –equivalent (SWE)

  • Sincesnowdensity is a functionofseveralfactors, manyobservationscan be used to increasedensitypredictionaccuracy

  • The densityequation is

    whereb is the Global SnowDensity gradient


Local vs global snow density

Localvs Global SnowDensity

LocalDensity

Global Density

  • Used to calculatetheaveragedensity for thisscan

  • Can be automaticallyselected if position data is registered in thesnowdensity form

  • Used to calculatethe global density gradient

  • Linear regression is performed to calculateb

  • Outlierscan be automaticallydiscarded


Snowdensityforscanform

SnowDensityForScanForm

Equipment used to takemeasure

Automatic outlierremoval

Measureddensity

UTM positionofthisobservation

Depth measured

StdErrorofselectedmeasures

Gross weightmeasured

R2ofselectedmeasures

Excludethisobservation by removingcheck mark

Visualization

Global Densityequation


Snowdensityforscanform1

SnowDensityForScanForm

Automatic selection (Requiresposition data)

Selected for localsnowdensity

Distance from thisobservation to thisscan

Resultinglocalsnowdensity

Localsnowdensityequation

Global snowdensity gradient, b


Data export

Data Export

Saving data…


Export ground profile

ExportGroundProfile

  • Whenthe «Export» menu is selected, a report preview is created:


Export formats

Export formats

  • MS-Word

  • Excel

  • PDF

  • Canalso be printeddirectly


Report contents

Report contents

  • Header contains

    • Averagedepth for thescan

    • Average SWE for thescan.

    • Signal Velocity used

    • SnowDensity Equation


Report contents1

Report contents

  • Report footercontains

    • Depth References

    • SnowDensities

    • Filter configuration


Saving data

Saving data

  • The analysiscanalso be saved to a .SIRDAS file

    • Contains all raw data used to generatetheroute

    • Containstheimagegenerated by theraw data (as a picture)

  • .SIRDAS files can be used

    • To quicklyreviewhistoric data

    • To update SWE report data by modifying Depth Reference information or SnowDensityMeasures

  • In order to save disk space, SIRDAS files can not be used to

    • Edit routeinformation

    • Edit analysisconfiguration


Advanced features

Advanced features

Manual routecorrection

Analysis configuration


Manual route override

Manual Routeoverride

  • Sometimesthe SIRDAS analysis is unable to make a correctpaththroughthe data points.

  • Checkthe«Draw Route»

  • Useright mouse toadd manual points

  • Recalculateroute to checkeffect


Sirdas configuration

SIRDAS Configuration

Filters, PeakDetectors and RouteFinders


Filter configuration

Filter configuration

  • Horizontal filters

    • CutOffFilter – Removeslarge signal from first snowecho

    • DepthFilter – Compensates for attenuation in snow

    • LowPassAndMagnitudeFilter – Removeshigh-frequencyoscillations, and converts sample value to amplitude


Configuration form

Configuration form

  • User interface for changingconfiguration

  • Shows previewof original data and filtered data

Choose filter order and type

Configureselected filter

Preview filter effect

Whichshot to preview


Cutofffilter

CutOffFilter

  • Removesthelarge signal from thesnowsurface

  • Averages first n samples in all shots

  • Looks for first sample whereaverage is belowtreshold:


Depth filter

Depth filter

  • Compensates for the signal attenuation in snow:

b=0:

b=0.1:


Lowpassandmagnitudefilter

LowPassAndMagnitudeFilter

  • SmoothingFactor=0:

  • SmoothingFactor=1.3


Horizontal filters

Horizontal filters

  • Combinesshotsthatare «close» – requires GPS information to be present in radar data.


Peak detector

Peak detector

  • Detectspeaks in thefiltered data – not really used anymore. (Version 3.0 used peaks, 3.1 has an improvedroutefinderalgorithm).


Route finders

Routefinders

  • This is thecorealgorithm in SIRDAS.Net

    • Version 3.1 introducedthe«Advanced CheapestCostRouteFinder»

    • Uses DIJKSTRA algorithmto calculatethe «cheapest» paththroughthe radar data.

    • Relies on a tunablecostfunction – thisfunction makes it «expensive» for theroute to make large jumps, and makes it «cheap» og throughstrong data points

    • The parameters can be tuned – see tooltip for explanation.

  • The otherroutefindersare less accurate, butare faster. Theyshould be avoided, and arekept in theproductprimarily for historicreasons.


Options

Options

Display options


Options1

Options

  • Zoom Y-axis: Checkthis in order to zoom on the Y axis

  • Show Raw Data: Show the data withoutthehorizontalpositionfilter applied

  • Absolute sample coloring:Whenselected, thecolor showing theechostrength is scaledglobally – defaultvalue is thateachshot is scaled to maximizevisibility.The relative sample coloring makes weak signals lookstrong – useabsolutecoloringwhenyoususpectthis…


Plot navigation1

Plot navigation

  • Mouse wheel is supported

    • Ctrl+wheel zooms in and out

    • Wheel pans left and right (Afteryou have zoomed)

  • Zoom out

    • By usingthemousewheel

    • By pressing the zoom outbutton:

  • Zoom in

    • By selecting a range

  • Pan

    • By mouse or keyboard.

    • Ctrl-arrowmoves to start or end


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