Transcript MultiLoop III - Tutorial 3 - Lamontagne Geophysics Ltd.

MultiLoop III - Tutorial 3
Creating a Grid & Plotting Vectors
(Continued from Tutorial 2)
Step 1: Create the grid
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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.
From the “Survey” menu,
select “Edit Grids”
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
Create a grid with the parameters
given in the edit boxes to the right
Colouring options
Replots the grid with the
parameters selected, recomputes
scattered vectors
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
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.
The new grid name
appears in the grid
selector
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.
Step 2: Compute scattered fields
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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
Click on “Hatching“
to add hatching
Hatch marks are then shown at the
discretization points
Click “Update” to update the scattered
vector fields on the grid.
A confirmation message will appear to confirm that
the scattered vectors should be recomputed.
Click “Yes”
The scattered vector fields are recomputed and plotted
To work more with scattered vectors, exit the
“Define Grid” dialog
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.
The profile plots are removed; the grid with
the scattered vectors is easier to see.
To edit the scattered vectors, click “Vectors”
on the “Plot” menu
This brings up the “Plot Magnetic Field Vectors” dialogue
The “Plot Magnetic Field Vectors” dialogue
Vector Data
Selector: shows
existing vector
data
Two vector
fields can be
overlain
A 3-component
(X,Y,Z) field is
plotted
No field is
plotted in the
second
selection
Vector plots can be created
or deleted. Here are no
vector data available to
create a plot, so “Create
Plot” is grayed out.
Normalized or unnormalized
vectors can be plotted
The scale sets the size of
vectors plotted
Settings: “Auto” sets the
scales and colours
automatically
The vector field for channel
“Eq_0” is plotted
The vector plot can be hidden from view
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
The vector field for the selected channel will be plotted
Step 3: Plot a second channel
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Select how the vectors will be plotted
Select the channel to plot
Go
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
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
Two 3-component vector fields are now plotted
The vector fields compare channels UT_6 and UT_1
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.