MultiLoop III - Tutorial 3

1. MultiLoop III - Tutorial 3 Creating a Grid & Plotting Vectors (Continued from Tutorial 2)

2. Step 1: Create the grid • Complete Tutorial 1 and 2. • From the “Survey” menu, select “Edit Grids” • The “Define Grid” dialogue will appear • Enter the properties of the grid to create • Select “New” • A grid will be created. • Go.

3. From the “Survey” menu, select “Edit Grids”

4. The “Define Grid” Dialogue appears, sensible default values will be computed. The grid location in space The coordinate on the grid located in space Grid selector Orientation Length of the sides Calculated strike and dip Discretization Hatching and back-plane toggles Colouring options Create a grid with the parameters given in the edit boxes to the right Replots the grid with the parameters selected, recomputes scattered vectors

5. Edit the reference point, rotations, strike length and dip extensions to parameterize the grid you want. …these parameters can be changed later, so don’t be too concerned to set them perfectly the first time through. When, done, click “New” to create the grid

6. When a new grid is created, the “Grid Selector” will need a name for it. A suggested name will be automatically generated. Set the name you want and click “OK” to create the grid. Often the suggested name will be good enough, and does not need changing. If a duplicate grid name is entered, a grid will not be created.

7. The new grid name appears in the grid selector

8. The grid should appear in the graphic window. If it does not, check the orientation and reference point parameters to ensure the grid is properly located. Check the strike length and dip extension to ensure the grid is the proper size. Hint: If the grid cannot be seen, Turn on the backplane to help locate the grid. Also check the “Show” option in the “Plot” menu, to ensure that grids are showing.

9. Step 2: Compute scattered fields • Add hatching to the grid • Compute the scattered vector fields and view the default plot • Remove the profile plot from view • Select a new channel to view as scattered vectors • Go

10. Click on “Hatching“ to add hatching

11. Hatch marks are then shown at the discretization points

12. Click “Update” to update the scattered vector fields on the grid.

13. A confirmation message will appear to confirm that the scattered vectors should be recomputed. Click “Yes”

14. The scattered vector fields are recomputed and plotted

15. To work more with scattered vectors, exit the “Define Grid” dialog

16. To remove the profiles from the display (the profiles will still exist, but will just not be shown), from the “Plot” menu, select “Show” and click on “Response Profiles”. This makes the display less cluttered, so working with the scattered vector plots is easier. This is done as a matter of convenience only. The Response Profiles can be redisplayed at any time by repeating this operation.

17. The profile plots are removed; the grid with the scattered vectors is easier to see.

18. To edit the scattered vectors, click “Vectors” on the “Plot” menu

19. This brings up the “Plot Magnetic Field Vectors” dialogue

20. The “Plot Magnetic Field Vectors” dialogue Vector plots can be created or deleted. Here are no vector data available to create a plot, so “Create Plot” is grayed out. Vector Data Selector: shows existing vector data Normalized or unnormalized vectors can be plotted Two vector fields can be overlain The scale sets the size of vectors plotted Settings: “Auto” sets the scales and colours automatically A 3-component (X,Y,Z) field is plotted The vector field for channel “Eq_0” is plotted No field is plotted in the second selection The vector plot can be hidden from view

21. To change the channel plotted, click on the button in the Channel column A “Select the gate name” dialogue will appear. Select the gate name from the list box Click “OK” when done

22. The vector field for the selected channel will be plotted

23. Step 3: Plot a second channel • Select how the vectors will be plotted • Select the channel to plot • Go

24. To plot the second vector field, click on the Component, in this Case “No Selection” is showing A “Set Component” dialogue will appear. Select the component from the radio button list Click “OK” when done

25. As before, to change the channel plotted, click on button in the Channel column A “Select the gate name” dialogue will appear. Select the gate name from the list box Click “OK” when done

26. Two 3-component vector fields are now plotted The vector fields compare channels UT_6 and UT_1

27. To zoom in, use the magnifying glass or type “i” Channel UT_1 large amplitudes are plotted in red, smaller amplitudes in purple Channel UT_6 is plotted in purple (large) and blue (small) Detail of the vector field Each vector field is plotted with its own colour scheme. The colour used varies with the magnitude of the vector.