This is perhaps the easiest way to create a reference matrix (DTM), provided that an AutoCAD or MicroStation CAD drawing of the area is available (and of course, contains elevation information). From the vectors collected from the CAD file, a TIN model is generated and heights are calculated on the generated triangles. When comparing the matrix created from a sounding with a matrix created from a CAD drawing, we can calculated the amount of material which has to be (re)moved in order to get the result as defined in the CAD drawing (dredging volumes). A sample CAD design of how to construct a basin is displayed below: To start the conversion, right click on the loaded DXF or DGN CAD file, and select the ‘Export to Matrix…’ option.: After selecting this option the ‘Generate Matrix from vector map’ dialog will be displayed, as shown in the image below: Use this control to select the vector map to generate the matrix from. Please note that only vector maps are displayed here, raster maps do not contain elevation information. By default the ‘Active Layer’ is selected in this control. Enter the names of the layers that should be included in the calculation. To enter multiple names, just separate them using semicolons. This field is required, when left blank, there will be no generation of matrix data. Set the required spacing. Please note that when using the volume calculation using matrices, this spacing should be equal to the one used in the matrix generated from the sounding. Select which area or boundary will be used to indicate the clipping area of the matrix generated from the sections. When you want to disable clicking, select the default option ”. Click the browse button to select a folder and file name for the generated matrix. The matrix is saved as an ASCII file containing all the XYZ pairs calculated by this tool using TIN. When all parameters has been set, the matrix will be calculated and added to the project. During the generation process, a progress bar will be shown in the status bar. The following video tutorial shows how to generate a reference matrix or DTM from a loaded AutoCAD file. It also shows how to create a boundary from DXF. Source.