SIRDAS.Net

SIRDAS.NetIntroduction to SIRDAS.Net

Slides for workshop with StatkraftMarch 10, 2011Espen Halsaa Albrektsenespen@albrektsen.nethttp://www.albrektsen.net/sirdas

AgendaGetting startedInstallationWhat is SIRDAS.NetBasic operationOpening a fileDepth Reference measurementsSnow Density measurementsData exportAdvanced operationManual route correctionData analysis tuningVertical filtersHorizontal filtersRoute finderGetting startedDownload and install SIRDAS.Net fromhttp://www.albrektsen.net/sirdas You need some Microsoft tools these are downloaded automatically if not allready installed on your systemStart the application, and request a license keyA request is posted to my web site I manually generate a license key and email back to you.(Expect 1-3 bussiness days delay)Start the application, and register the license keyStart the application you are good to go! Basic OperationSIRDAS.Net supports the NogginPlus file formatEach scan consists of 3 files, with file types .dt1, .hd and .gps. These three files must be in the same directory and have the same filename:

When a .dt1 file is selected for analysis, SIRDAS.Net immediately starts processing the file data.If the NogginPlus file contains reference points (Fiducial Markers in the NogginPlus manual). SIRDAS.Net assumes that a NogginPlus Fiducial Marker is a manual depth measurement, and allows the user to enter this information.

Plot navigationMouse wheel is supportedCtrl+wheel zooms in and outWheel pans left and right (After you have zoomed) Zoom outPress ESC keyBy using the mouse wheelBy pressing the zoom out button:Zoom inBy selecting a rangePanBy mouse or keyboard. Ctrl-arrow moves to start or end

Depth ReferencesUsed to calibrate wave propagation velocity, and to to adjust for equipment-specific depth offsetPurposeUsed to calibrate the conversion between sample index and depth.Average wave velocity defaults to 0.2m/nsThe radar signal is sampled at a fixed interval (samplerate) a sampleindex is therefore a representation of the two-way travel time from radar to ground and backThe wave velocity varies with snow density and needs to be calibrated

Zero-levelZero-level is initialized to the value calculated by the Cut-off-filter. (See filter section for details)The zero-level offset depends on equipment and also needs to be calibrated.Zero-level can be updated manually, or reference points for zero level can be entered.Depth Reference Form

RouteSampleIndex is updated once a a route is found ShotIndex is the position of this Depth referenceDepth is manually entered by the userWaveVelocity for this shotAverage wave velocitySample index for zero depthDepth Reference Form

Depth Reference Form

Reference point is plotted at correct depth and positionZero-level offset clearly visible in graphZero-level indexInitialized by analyzing the average energy in the first 100 samples of all shots:

Manual override eitherBy entering a depth reference of zero metersOr by adjusting zero sample index directly

Snow Density ObservationsUsed to calibrate the formula for converting snow depth to snow-water equivalent (SWE)Snow Density MeasurementsLocal vs Global Snow DensityLocal DensityGlobal DensityUsed to calculate the average density for this scanCan be automatically selected if position data is registered in the snow density formUsed to calculate the global density gradientLinear regression is performed to calculate bOutliers can be automatically discardedSnowDensityForScanForm

Exclude this observation by removing check markUTM position of this observationDepth measuredAutomatic outlier removalGross weight measuredEquipment used to take measureMeasured densityStdError of selected measuresR2 of selected measuresGlobal Density equationVisualizationSnowDensityForScanForm

Selected for local snow densityDistance from this observation to this scanResulting local snow densityAutomatic selection (Requires position data)Global snow density gradient, bLocal snow density equationData ExportSaving dataExport Ground ProfileWhen the Export menu is selected, a report preview is created:

Export formatsMS-WordExcelPDF

Can also be printed directly

Report contentsHeader contains Average depth for the scanAverage SWE for the scan.Signal Velocity usedSnow Density Equation

Report contentsReport footer containsDepth ReferencesSnow DensitiesFilter configuration

Saving dataThe analysis can also be saved to a .SIRDAS fileContains all raw data used to generate the routeContains the image generated by the raw data (as a picture).SIRDAS files can be usedTo quickly review historic dataTo update SWE report data by modifying Depth Reference information or Snow Density MeasuresIn order to save disk space, SIRDAS files can not be used toEdit route informationEdit analysis configurationAdvanced featuresManual route correctionAnalysis configurationManual Route override Sometimes the SIRDAS analysis is unable to make a correct path through the data points.Check the Draw RouteUse right mouse toadd manual pointsRecalculate route to check effect

SIRDAS ConfigurationFilters, PeakDetectors and RouteFindersFilter configurationHorizontal filtersCutOffFilter Removes large signal from first snow echoDepthFilter Compensates for attenuation in snowLowPassAndMagnitudeFilter Removes high-frequency oscillations, and converts sample value to amplitudeConfiguration formUser interface for changing configurationShows preview of original data and filtered data

Choose filter order and typeConfigure selected filterPreview filter effectWhich shot to previewCutOffFilterRemoves the large signal from the snow surfaceAverages first n samples in all shotsLooks for first sample where average is below treshold:

Depth filterCompensates for the signal attenuation in snow:

b=0:b=0.1:LowPassAndMagnitudeFilterSmoothingFactor=0:

SmoothingFactor=1.3

Horizontal filtersCombines shots that are close requires GPS information to be present in radar data.Peak detectorDetects peaks in the filtered data not really used anymore. (Version 3.0 used peaks, 3.1 has an improved route finder algorithm).Route findersThis is the core algorithm in SIRDAS.NetVersion 3.1 introduced the Advanced Cheapest Cost Route FinderUses DIJKSTRA algorithm to calculate the cheapest path through the radar data.Relies on a tunable cost function this function makes it expensive for the route to make large jumps, and makes it cheap og through strong data pointsThe parameters can be tuned see tooltip for explanation.The other route finders are less accurate, but are faster. They should be avoided, and are kept in the product primarily for historic reasons.OptionsDisplay optionsOptionsZoom Y-axis: Check this in order to zoom on the Y axisShow Raw Data: Show the data without the horizontal positionfilter appliedAbsolute sample coloring:When selected, the color showing the echo strength is scaled globally default value is that each shot is scaled to maximize visibility.The relative sample coloring makes weak signals look strong use absolute coloring when you suspect thisPlot navigationMouse wheel is supportedCtrl+wheel zooms in and outWheel pans left and right (After you have zoomed) Zoom outBy using the mouse wheelBy pressing the zoom out button:Zoom inBy selecting a rangePanBy mouse or keyboard. Ctrl-arrow moves to start or end