Depth Filtering

Owned by Tore Sannes (Unlicensed)
Last updated: Oct 13, 2014
2 min read

In this section:

Introduction

This command is executed from folders of schema type Multibeam, Soundings, Single Beam or Generic. The command will operate on data with schema type Multibeam Survey, Pointcloud or Poly Data. The command is removing data accordig to the filters defined in the dialog.

When executed from a Multibeam folder the name of the command will be Multibeam Depth Filtering.

When executed from a Soundings, Single Beam or Generic folder the name of the command will be Depth Filtering.

 

For Multibeam Survey and Pointcloud data the removed data will be flagged as Filtered, and also named with the actual filter type. The filtering can be reverted by the Revert Flagged Points command. 

For Poly Data the original data item is kept, and the filtered dataset gets the extension _Filtered.

 

The Depth Filtering dialog.


The content of the menu

The Threshold filter part:

The Threshold filter check box: Activate the check box to turn on the filter.

  • Remove shallower than depth (m): Activate the check box to turn on the filter. Enter the depth value for minimum depth in the input field.
  • Remove deeper than depth (m): Activate the check box to turn on the filter. Enter the depth value for maximum depth in the input field.

Only the checked remove selections will be performed. When executing the filter several times on the same dataset, the selected filter will be reverted before the next is applied if the data set is Multibeam or Pointcloud. 

 

The Surface filter part:

The Surface filter check box: Activate the check box to turn on the filter. 

The two radio buttons:

  • Use Surface: Filter the depth versus the specified surface. To insert the surface: Locate the surface (Structured Points) in the project and then click the green arrow to the right of the input field.
  • Make Surface: Use the selected datasets to create a surface using a default gridding method (Weighted Average). The increments and gridding result is written to the report.

Filter type:

  • Standard deviation: Filter using limits from a standard deviation calculation.  Calculate the standard deviation from all input points versus the surface. The standard deviation is multiplied with the shallow factor and the deep factor to get the filter limits.
  • Absolute: Filter using absolute limits. The depth are filtered by absolute distance from the surface.
  • Relative: Filter using limits in % of the depth range. For each point, get the depth from the surface. Calculate the shallow and deep limits by multiplying the % value limit with the depth.

Use deep limit=shallow: Use the same limit on both the shallow and deep side of the surface.

Shallow factor: Factor for multiplying the calculated standard deviation as limit on the shallow side of the surface.

Deep factor: Factor for multiplying the calculated standard deviation as limit on the deep side of the surface.


The Dataset or Surfaces part:

Select the datasets of selected type to execute the depth filter on.