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Introduction

The command Surface cut/fill volumetrics calculates the cut and fill volumes between two surfaces or between a surface and a polygon data set representing the theoretical terrain.
The cut volume can be seen as the volume to be dredged (positive volume), whereas the fill volume is the volume to be filled (negative volume).
The command reports the volume and the area (horizontal projection) of the cut and fill volume in a text item.

In addition this command can produce the following products:

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CUBE (Combined Uncertainty and Bathymetric Estimator) is an error-model based, direct DTM generator that estimates the depth plus a confidence interval directly on each node point. The CUBE library is developed by University of New Hampshire.

The implementation in Geocap Seafloor is modfied to work with echo sounder models which were not in the market when Cube was created. The latest release of the Cube library was in 2004.

The output of the command is a depth surface named Surface_Cube_<depth algorithm>. The surface can also contain additional attributes like Uncertainty, DepthHypothesesNumber and HypothesisStrength dependent on the selected options in the dialog. The result will also be named with the attribute.

The content of the menu

The Surface cut/fill volumetrics command can have two possible input for the cut data:

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The Surface cut/fill volumetrics dialog with input polygon data.

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The Surface cut/fill volumetrics dialog with input surface data.

Terrain Surface

The Terrain surface part gives information of which surface the command is started from. This is the surface which will be cut during the volumetrics calculation.

The original surface itself will not be manipulated, just copied.

Cut surface/polygon

In the Cut surface/polygon part the gives information of which surface the command is started from. Select a Poly Data or Structured Points (surface) data set in the project and click the Image Removed button beside the text field.

When starting the volumetrics with a Poly Data set as input, the ply data will be triangulated to a surface model. The better the polygon describes the actual cut surface the better the result the volumetrics calculation will be. The surface created from the poly data is named as the Cut surface.

The calculation of the volumes is done by subtracting the cut surface from the Terrain surface to get the difference surface.

Create cut surface

Create the cut surface from polygon data set.

The surface is saved with the name CutSurface in a subfolder named Volumetrics in the same folder as the terrain surface is located.

Create difference surface

The difference surface is the Terrain surface minus Cut surface.

The surface is saved with the name DifferenceSurface in a subfolder named Volumetrics in the same folder as the terrain surface is located.

Create terrain with cut

What the terrain would look like if the parts of the terrain that is higher than the cut surface was replaced by the cut surface.

The surface is saved with the name TerrainWithCut in a subfolder named Volumetrics in the same folder as the terrain surface is located.

Create terrain with fill

What the terrain would look like if the parts of the terrain that is lower than the cut surface was replaced by the cut surface.

The surface is saved with the name TerrainWithFill in a subfolder named Volumetrics in the same folder as the terrain surface is located.

Create cut area

Horizontal projection (z=0) showing those parts of the terrain surface that would be cut.

The surface is saved with the name CutArea in a subfolder named Volumetrics in the same folder as the terrain surface is located.

Create fill area

Horizontal projection (z=0) showing those parts of the terrain surface that would be filled.

The surface is saved with the name FillArea in a subfolder named Volumetrics in the same folder as the terrain surface is located.

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The CUBE dialog for multibeam data and CUBE for XYZ data in a Soundings folder.

Input Data

The Input data part of the dialog is where to select which data items to be gridded. The CUBE command works with both multibeam data (Survey Line) and with XYZ data (Dataset). Select data items from the list.

The rows X, Y and Z are automatically updated with the minimum and maximum extensions of the coordinates from the selected files.

The Coordinate System field shows the type of coordinate system for the data.

Cube Algorithm Parameters

The Cube Algorithm Parameters part is where to specify parameters for the CUBE depth processing. The parameters to set:

Depth Estimation Algorithm
Grid increments
Error Distribution Model Algorithm

Depth Estimation Algorithm

The options for the depth estimation algorithm are:

Nodal estimate algorithm: This is the default algorithm for the implementation of Cube. It will create the depth surface and the operator can select to also create the Uncertainty attributes to the cube_depth_surface.

Bined mean algorithm: This algorithm will create the surface based on the mean values in the bins (cells). No attributes can be created.

Bined median algorithm:This algorithm will create the surface based on the median values in the bins (cells). No attributes can be created.

HyperCUBE super-grid: The HyperCUBE super-grid is creating a grid based on several hypotheses from the depth data. In addition to the depth grid this algorithm can also create the attributes Uncertainty, DepthHypotheses and HypothesisStrength as output in the Surface_Cube_<depth algorithm>. ~~This depth estimation algorithm is implemented for multibeam data only~~. This algorithm is currently not available in Geocap Seafloor.

Grid increments

Specify the increments:

X Increment (m): Specify the increments in X-direction (Easting) for the result grid.
Y Increment (m): Specify the increments in Y-direction (Northing) for the result grid.

The lower left corner and the upper right corner of the result grid will be rounded down and up to contain the increments. (A 5 meter grid increment result in a lower left corner starting on an integer value of 5 meter.)

Error Distribution Model Algorithm

Specify the type of the error distribution

FULL: Implemented for multibeam data only. Will use all information from the multibeam data's Vessel Configuration to estimate as accurate as possible the
IHO: Implemented for multibeam data and XYZ data. When selected, the IHO order can be specified below.

The IHO Order (prediction model):

- Special Order: Areas where under-keel clearance is, i.e. the depth is less than 40 meters.
- Order 1a: Areas shallower than 100 meters where under-keel clearance is less critical, but features of concern to surface shipping may exist.
- Order 1b: Areas shallower than 100 meters where under-keel clearance is not considered to be an issue for the surface shipping expected to transit the area
- Order 2: Areas generally deeper than 100 meters where a general description of the sea floor is considered adequate.

Output

Select options for what output to create.

Depth Surface: The depth surface will always be produced in the Surface_Cube_<depth algorithm> result surface.

Uncertainty Surface: When using the depth estimation algorithms Nodal estimate algorithm or HyperCUBE super-grid this option can be checked. The Uncertainty values will be an attribute in the Surface_Cube_<depth algorithm>. The text "_Uncertainty" will be added to the result name.

Number of Hypotheses Surface: When using the depth estimation algorithms Nodal estimate algorithm or HyperCUBE super-grid this option can be checked. The DepthHypothesesNumber values will be an attribute in the Surface_Cube_<depth algorithm>. The text "_HypothesesNumber " will be added to the result name.

Hypothesis Strength Surface: When using the depth estimation algorithm HyperCUBE super-grid this option can be checked. The HypothesisStrength values will be an attribute in the Surface_Cube_<depth algorithm>. The text "_HypothesisStrength" will be added to the result name. Since the algorithm HyperCUBE super-grid is currently not available, this output will not be possible.

The Results

After executing the volumetrics a dialog will pop up showing the parameters, result and volumes from the calculations. The report itself is saved in the project structure in

e

a folder named Reports

located in

under the same folder as the

terrain surface

command is executed from. The report itself is named as YYYYMMDD

Surface cut/fill volumetrics

HHMMSS CUBE (the name of the executed command).

All reports from all runs will be saved in the Reports folder.

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