Eye4Software Hydromagic

Hydrographic Survey Software

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Apply offsets

The "Apply Offsets" tool can be used to apply fixed offsets to a couple of vertical measurements,
including depth, tide, mean see level, ellipsoidal height and heave.

The tool can be used to correct or inverse motion sensor (IMU) data as well.

To start applying offsets to your data, click the "Offsets" button from the "Data processing tools collection" screen,
which can be opened by clicking the "Tools..." button on page 5 of the sounding wizard.

Apply offsets to raw data files

Configuring offset options


Use the "Depth (Hi)" and "Depth (Lo)" fields to correct the measured depth.
You can use this function when you created a sounding without, or with an incorrect transducer offset.


Use the "Tide" field to apply a fixed offset to the tide values.
This function can be used to apply a fixed tide, or to correct your tide receiver or RTK tide measurements.

Mean Sea Level

Use the "Mean Sea Level" field when you use the MSL field from your GPS to calculate tide levels.
This is only used in rare cases where a geoid has been programmed in the RTK receiver,
and the MSL field is used to output the height relative to a vertical datum.

Ellipsoidal Height

Use the "Ellipsoidal Height" field to correct the height measured by a RTK receiver.
This correction can be useful when an incorrect antenna height was configured during surveys.


Use the "Heave" field to correct heave values in cases where the heave sensor wasn't correctly calibrated before performing a survey.
You can calibrate the heave sensor in the "Calibration" tab of the "Preferences" dialog.

Roll and Pitch

Use the "Roll" and "Pitch" fields to correct these motion values when an IMU wasn't correctly calibrated before performing a survey.
You can calibrate IMU sensors in the "Calibration" tab of the "Preferences" dialog.

Swap roll and pitch sign

Use this function to swap the angle direction of your IMU in cases where the following conventions are not met:

Positive roll value => starboard up;
Positive pitch value => stern up;
Negative roll value => port up;
Negative pitch value => bow up;

When your IMU works the other way around for one of the motion directions,
check the box to invert the value before using it to correct your sounding data.

Data selection

You can apply the offsets to a single or all raw data files. In most cases,
when an invalid setting was used during the entire survey, you have to apply the corrections to all files.

To start processing the data, click the "OK" button. This should not take longer then a couple of seconds, depending on the size of the data.