Qimera Glossary

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Active Dynamic Surface

Most dynamic surface operations in Qimera operate on the active dynamic surface. The active dynamic surface is either the currently selected dynamic surface, or if no dynamic surface is selected, the only visible dynamic surface.

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C

CCOM

Center for Coastal and Ocean Mapping at the University of New Hampshire in Durham, NH, USA.

Chimera

A monstrous mythological fire-breathing creature composed of the parts of multiple animals. These animals depicted are typically lion, goat, dragon, and snake. This was the origin of Qimera in that we have taken technologies from across QPS and created a powerful (fire breathing) bathymetric processing tool.

CUBE

CUBE (Combined Uncertainty and Bathymetric Estimator) is an algorithm that takes advantage of statistical redundancy in a dense collection of soundings. Tracking the uncertainty associated with these soundings, CUBE can make estimates of the true depth of water across a survey area.

D

Data Validation

Dot killing, getting rid of outliers, data cleaning

DTM

Digital Terrain Model. In the QPS software suite, the abbreviation DTM is used in different ways. In QINSy, the DtmData folder stores the QPD files used for generating a DTM. In Fledermaus, DTM SD files are Fledermaus-format files of gridded bathymetric or topographic surfaces. The Qimera Create Surface Object option creates a DTM SD, which is equivalent to the Static Surface.

Dynamic Surface (GRD)

The Dynamic surface will allow you to see a grid representation of the soundings you are working with. It is created by raw sonar data that has been sound velocity corrected or created by imported processed point files. This surface allows direct edit capability on the underlying sounding data and will automatically update when updates are complete.

Dynamic Workflow

Dynamic Workflow is an automated state machine based process that guides you through bathymetric processing steps, attempts to complete some steps (such as vessel extraction) automatically and determines the tasks that need to be accomplished next.

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EPSG

European Petroleum Survey Group format for storing coordinate system information. Wikipedia Reference

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I

IMU

Inertial Measurement Unit, often used interchangeably with MRU Wikipedia Reference

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L

M

Multibeam Echosounder

Echosounder that forms a triangular fan of multiple beams that provides several sounding solutions across the ship track with a single ping emission. A single beam echosounder provides a sounding directly below the sounder only.

MRU

Motion Reference Unit, often used interchangeably with IMU.

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NADIR

The point on the sea floor that lies directly below the sonar during a survey.

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OMG

Ocean Mapping Group at the University of New Brunswick, in Fredericton, NB, Canada.

P

Processed Point File

These are files that contain processed soundings/footprints with a minimum XYZ attribute for each sounding. Supported file formats can range from simple ASCII to GSF. Refer to this list of supported file formats.

Q

Qimera

See Chimera.

QPD File

This is the processed format of all sonar data imported into Qimera.

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S

SBET

Smoothed Best Estimate of Trajectory. An Applanix file format that contains the post processed inertial data from a POS MV. The data can include position, GNSS height, heading, and motion data (but not heave). Qimera requires the name "SBET" to to be in the name of the file to make it automatically detected. eg: SBET_11062015.out

SBTC / SBIC

Smoothed and combined (forward and reverse) tightly / loosely coupled trajectory. A NovAtel file format produced by their Inertial Explorer Software. The data can include position, GNSS height, heading, motion (including heave) and their standard deviations.

SD

Scientific Data Object. This is the storage format for Fledermaus visual objects.

SD

Standard deviation. A statistical parameter that describes the spread of measurements about their average. With a normal distribution, the SD gives the expected uncertainty level for any given measurement.

Sound Velocity

The speed that sound travels through a medium. This quantity is fundamental to echosounding since echosounders measure the travel-time of an acoustic pulse and the speed of sound is used to convert this into a range in linear units such as meters. Sound speed is the technically correct term, however, sound velocity is used throughout the marine geomatics industry and we have followed suit.

Sound Velocity Correction

The mathematical process which converts an observed two-way travel time measurement and launch angle relative to the horizontal to the depth and distance traveled by the acoustic pulse relative to its source.

Static Surface

The static Surface is data gridded from the processed (QPD) files. it's a static grid which won't change when editing (QPD) data.

T

TPU (Total Propagated Uncertainty)

The TPU of a point is a measure for the accuracy to be expected for such a point, when all relevant error / uncertainty sources are taken into account.

U

USGS

United States Geological Survey

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W

Water column

Acoustic backscatter returns between the water surface and the seafloor interface; this information has many uses, but in Qimera its intended use is to help you determine the validity of bathymetric targets. If water column data is acquired and stored with the bathymetry data, Qimera will scan it on on data load and make it available for viewing in the Water Column Window.

The pick and zoom interface object that appears in the 4D scene that provides navigation through direct interaction with the data space.

WKT

Well Known Text format for storing coordinate system information. Wikipedia Reference

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