Using matrices in Hydromagic Dredging
In Hydromagic Dredging, matrices are used to store updated depth or elevation information during the dredging process. A matrix is also known as a data grid or digital elevation model. In the dredging software, matrix files are also used to transfer soundings and when performing volume calculations (for instance to determine how much material already has been (re)moved).
Importing an existing matrix
Dredging progress can be recorded in an existing matrix file, for instance a matrix generated from a sounding in Hydromagic Survey. When the matrix file contains depth, the dredging software will overwrite matrix cells when dredging deeper than the values measured by the echo sounder.
When opening a survey project in the dredging software, matrices will be transferred automatically. When you want a separate project for dredging, right click the "Matrices" folder and select the "Import Hydromagic Matrix File..." option. Using the "Open File" dialog, you can select the matrix file which than will be imported into your dredging project.
Import an existing Hydromagic matrix file into your Hydromagic Dredging project.
Importing XYZ ASCII data
When you do not own a copy of Hydromagic Survey and your client supplies you with the pre dredge sounding in ASCII XYZ format, you can use the "Import ASCII XYZ Grid Data" tool to generate a matrix.To do so, right click the "Matrices" folder and select the "Import ASCII (XYZ) File..." option.
Generate a matrix from an ASCII file containing XYZ values.
Generating a matrix
When no pre-dredging matrix is available, you can generate an empty matrix which can be used to record data to. Before creating a new matrix, you should have drawn or imported a boundary. This area should be the area you are allowed to dredge in. It is recommended to keep the matrix size smaller than 1000 x 1000 meter, otherwise processing might become slow. For bigger area's just generate multiple boundaries and matrices. You can switch the matrix you are recording to by activating a matrix.
A new matrix can contain "void values", a fixed depth or elevation value, or it can contain values extracted from another (bigger) matrix. Please note that when you want to import data from an existing matrix, the cell size for the new matrix must match the cell size of the existing matrix.
When copying data from a matrix recorded with versions 9.2 or earlier, please check the "Import data from Layer-2 when loading version 9.2 matrices" check box. Matrices in versions 9.2 and prior did contain three layers, and dredging progress was stored in the second layer.
For matrix spacing, it is recommended to set the spacing to dredge head width divided by three. You get less accurate results when using a bigger cell size. Also select a file name for the matrix file to be created and click "OK" to start generation.
Generate an empty matrix file using the built-in tool.
Locking and unlocking matrices
When importing or generating a matrix, it will be set as "locked" by default. When a matrix is set to locked it means that it cannot be removed or updated with dredging depths. This is done to protect matrices from accidentally overwriting them. When you want to remove or activate a matrix, it has to be unlocked first. This can be done by right-clicking the matrix and selecting the "Unlock" option from the popup menu.
Three locked and one active matrix in the "Project Explorer".
Activating a matrix
To set a matrix as selection for updating, you need to "activate" it. This can be done by right-clicking the matrix and selecting the "Activate" option. You have to activate a matrix before recording data.
Select the "Activate" option to activate the matrix for recording.