Electrodes Tools

Table

By clicking with the right mouse button on the menu option “Electrode”, it is possible to manage the electrode information.

Figure 174 Tool Table

It is a table containing the electrode information. By default, the table shows the following columns (Figure 175):

Figure 175 Electrodes table

• Group: name of the cable. It is an editable column.

• ID: is a counter that is used to identify each electrode of the group. It is not editable. It’s not possible to associate a common “ID” to more than one electrode of the same group, but two or more electrodes of different groups can have the same “ID”.

• X(m), Y(m), Z(m): coordinates of the electrodes in the coordinate space. It is possible to change the value of X, Y, and Z by double-clicking the corresponding box.

• Zsurf (m): Z coordinate of the surface (if electrodes are positioned on the surface of the investigated area the Z and the Zsurf have the same value). It is possible to change the value by double-clicking the appropriate box. The two values are different for borehole survey.

• REM: flag marking a remote electrode. All electrodes have the red cross symbol except the remote electrode, which is instead identified by a green “V”. It is possible to change the flag by double-clicking the corresponding box.

In addition to the default columns, it is possible to add the following columns:

• TX: flagged with the green checkmark means that the corresponding electrode works as a transmitter. If it is flagged with a red cross the electrode works just as a receiver. This occurs normally with not-polarizable electrodes as it would be damaged if they would send current.

• RX: flagged with the green checkmark means that the relative electrode works as receiver. If it is flagged with a red cross the electrode works just as transmitter. Generally, the electrodes work both as transmitters and as receivers, so both flags are green by default.

• BOR: flagged with the green checkmark means that the relative electrode belongs to a borehole survey (and Zsurf is different from Z). If it is flagged with a red cross the electrode is located on the surface of the investigated area.

Note

Note that mark this flag is necessary to describe correctly borehole or underwater electrodes, where its Z coordinate is different from the Z coordinate of the terrain surface.

• SKIP: electrodes flagged with the red checkmark are not used during the sequence generation process, but they are still in the dataset (they are not deleted).

Note

Note that skipping an electrode does not affect the related measurements. To use electrodes to skip the measurements it is possible to use the command Skip Measurements using skipped electrodes.

• ROLL: electrodes flagged with the green checkmark are not used during the sequence generation process, because they are supposed to be already used with a previous roll and a different sequence.

If during the acquisition the roll method was adopted, the electrodes common at two consecutive lines can be marked with the green checkmark, otherwise, for normal electrodes they are usually marked with the red cross. In the following example (Figure 176), the electrode in blue of the second line (L2) can have “roll = V”.

Figure 176 Example of roll method

When the line L1 is acquired, the L2 line is positioned moving the electrodes from 1 to 7 and leaving the other electrodes in place. So the electrode 8, 9 and 10 of line 1 becomes electrode 1, 2 and 3 for line 2 (for convenience of representation L1 and L2 are here represented separated but in reality they would be on the same line and the electrodes in blue are not moved). The first six electrodes on line L2 should have the green “V” in the roll column

Figure 177 Example of roll sequence

In Figure 177 it is shown:

• A: a first line of electrodes, with its related measurements.

• B: the second line of electrodes with some common electrodes with the first line. To evaluate the common electrodes the measurements related the first line are also plot.

• C: the second line of electrodes, with its related measurements. The arrow points an empty area obtained during mesh generation setting the common electrodes as Roll on the second line.

This is useful to reduce the number of measurements that needs to be collected on the second line (and the following ones), because (if the settings in the Sequence genera panel was set correctly) they should be already collected thanks the acquisition on the first line. The reduction of the number of measurements should also reduce the total time needed in the field for the acquisition of the data, and also to reduce the total energy needed to collect all the measurements.

Left clicking on one of the column headings sorts all data in increasing order of that column. Left clicking a second times on the same column will sort the data in decreasing order.

A popup menu will appear (Figure 178) when clicking with the right mouse button in one box. The following options are possible:

Append Row

By clicking the left mouse button in one row (e.g. ID 7 in Figure 178) a new row will be added under the selected line (highlighted in yellow in Figure 178). By default, it will have the same value of the row from which it was copied from, but it is possible to modify the values.

Figure 178 “append new raw” in electrode table

Delete

To delete one row, just click with the right mouse button on the row you want to delete and choose Delete.

To delete several rows, select the desired rows by holding the left mouse button (the area will be highlighted in blue) then clicking the right mouse button and then “Delete”. In the following example lines from 5 to 10 are deleted.

Figure 179 Delete some electrodes from the table

Update Position from Picker

Through this tool it is possible to move one electrode from one position to another. If a point in the space has been stored with the Pick Tool (see section View Picker settings) his coordinates can be used to replace those already present in one row of the table.

In the following figure, a point is picked in space (pointed out by the arrow in Figure 180) at the coordinate:

X = -8m

Y = -6m

Z = 0m

Figure 180 One point in the space selected by the picker point

If this point should replace one already present in the electrodes table, click with the right mouse button in the row to replace by choosing “Update Position from Picker “. In the following example the picked point (black point in Figure 181) replaces the coordinate of the electrode 72 (blue point in Figure 181, highlighted by the blue arrow), which was positioned in 0,0,0.

Figure 181 Update electrode position using Picker Point coordinates

The electrode 72 was moved to the new position, as is shown in the table and in the plot.

Append point using a picker

Through this tool it is also possible to add one or more electrodes to the existing ones. By clicking with the right mouse button in the row of the table where to add the point and using the coordinates saved with the picker point (as explained in Update position from Picker).

Figure 182 A point in the space is selected to add one or more electrodes

In the window that appears (Figure 182) the user can choose the Step a Number values. These values are useful for multiple inserts, where the first point corresponds to the one selected in the table and last to the coordinate of the picker point. “Step” determines the space between two points (the number of intermediate electrodes is calculated accordingly), or vice versa. “Num” determines the number of electrodes to insert between the first and the last electrode (and Step is calculated accordingly). There are different combinations available for the two values:

• Step=0; Num=0 (default): only one electrode is inserted at the position determined by the picker point (Figure 183).

  

  Figure 183 One electrode is added to the scene at the picker point coordinates

• Step= n; Num=0: some electrodes are inserted in the line, starting from the point of the selected row in the table until the clicked picker point, proceeding with steps equal to the specified values. The electrodes are placed in the scene automatically. As a consequence of the step and the starting-ending position choices the numbers of the added electrodes are automatically found (Figure 184).

  

  Figure 184 More electrodes are added to the scene, choosing the spacing of 1m from each other’s

• Step = 0; Num = n: a defined number “n” of electrodes is inserted inline, starting from the selected row of the table until the clicked picker point. The sensors are placed in the scene automatically, so the step between them is automatically found.

  In the following example, 3 electrodes are added from electrode 72 (row highlighted in blue in the table) to 75, which coincide with the coordinate of the picked point.

  

  Figure 185 More electrodes are added to the scene, choosing the number of electrodes to add from the position of the selected electrode in the table to the picker point coordinates

• Step = n; Num = m; in this case exactly the specified number of electrodes are placed. Spaced by the values specified. It starts from the selected electrode in the table and it proceeds in the direction of the picked point (which can be further by some electrodes, or never been reached).

  

  Figure 186 More electrodes are added to the scene, choosing the spacing and the number of electrodes. In this case the last electrode (num 76) does not reach the position of the picker point

Set to

Through this command it is possible to manually edit more than a single cell value in the table.

Figure 187 The “Set to …” menu

It is possible to select just one cell and use the “Set to …” command to change its value, or it is possible to select several cells (in the same column) and use the command “Set to …” to change them all at once. In this paragraph there is a description of the different results obtained selecting cells from different columns of the table.

• Group: selecting one or more cells in this column makes it possible to change the Group Name for the selected electrodes. A window will be shown to ask the user the new name; click on “OK” button to apply. The specified name can be a new group or the name of an already existing group.

  

  Figure 188 Provide the group name

• ID: this column is automatically generated, so it is not possible to edit it.

• X [m]: selecting one or more cell in this column makes it possible to change the X coordinate of the selected electrodes. A window will be shown to ask to the user the new value(s); to apply, click on “OK” button. If the “Start Value” and the “Stop Value” are the same, all the cells will be filled with the same value; if they are different, the selected cells will be filled to fit the range specified computing the needed increment automatically.

  

  Figure 189 Provide the range values

  The following image shows an example of how to set a value of 10 as “Start Value” and a value of 32.5 as “Stop value” to a selection of 10 cells. A step of 2.5 and 9 increments between cells are automatically found to satisfy the specified range.

  

  Figure 190 Example of setting a linear range of values for cells on “X” column

• Y [m]: analogous to X [m] column, see above.

• Z [m]: it is almost the same as the “X” column, but with the following difference. The window shown has some more parameter to be checked before continuing.

  

  Figure 191 Provide the range values

  If “Length by Z interpolation” is checked the increment automatically found to fill the cells will be not constant but proportional to the electrode distance on the “XY” plane. In the following example 10 electrodes are used, all of them are lying along the “X” axis, the first 5 electrodes are located with a spacing of 1m, then it becomes 4m. In Figure 192 A it is shown how the “Z” values are computed with the default settings. Note that the gap between the electrodes along the “Z” axis is constant (always 0.8m). In Figure 192 B, the effect of the “Length by Z interpolation” tool is shown. The gap between electrodes along “Z” axis is not constant (it is 0.3m for the first 5 electrodes and 1.2m for the other electrodes which are more distant from each other). The graphic achievement is that in the second case the electrodes can be fitted with a straight line.

  

  Figure 192 Example of using the “Length by Z interpolation” tool

  If “Copy ONLY Z and Z Surf ” is checked, all the other parameters specified in the window will be ignored and the “Z” column will be filled with the values found in the “Z surf ” column.

• Z surf [m]: same as the “Z” column. The only difference is that when “Copy ONLY Z and Z Surf ” is checked then the result will be the opposite, so the “Z surf” column will be filled with the values found in the “Z” column.

• TX, REM, BOR, Skip Roll: these columns contains binary flags, when the “Set to …” command is invoked. The windows shown in Figure 193 asks the user the new status that the cells need to have. It is required to check or unchecked the parameter displayed and to press the “OK” button to apply the selection to all the cells highlighted.

  

  Figure 193 Provide the range values

Electrodes Rototranslation

It is possible to rotate or translate the selected electrodes. See Rototranslation.

Skip Measurements using skipped electrodes

With this command it is possible to filter the files measurements according to some electrodes that is supposed to give bad data in the field. Note that this menu option is available only when at least one electrode is marked as Skip.

For example, if one electrode did not work during acquisition, it is possible to delete the related measurements from the inversion following this process:

• Mark the Skip box of the electrodes with the green checkmark, by double-clicking the appropriate box (Figure 194, e.g. electrodes 3, 6 and 7);

• Right-click anywhere inside the table;

• Click on Skip Measurements using skipped electrodes.

With this function the measurements involving the electrodes marked by the checkmark will be not used for any inversion, but they are still in the dataset (they are not deleted, so it is possible to retrieve them later).

Figure 194 Electrodes Table_Skip measurements

Select Visible Columns

With this function it is possible to customize how the table is displayed, so it is possible to show or hide the available columns in the table. It is possible to choose columns one by one or to visualize all of them by selecting “Show all”, as in the following example (Figure 195):

Figure 195 “show all” columns in electrodes table

Create/Edit

Clicking with the right mouse button on the node “Electrode”, choosing “Tool” and Create/Edit will open a new window.

Figure 196 Tool Create/Edit

This panel contains a complete subset of tools to manage the electrodes.

Figure 197 Create/Edit tool

Current working group

On the top of the panel there is a selection box that allows to select the Group Name to edit. When the project does not contain any electrode, the previous list contains only the “All” option, else the list contains also all the electrode group names (Group_A/B/C/D in the example below).

Figure 198 Current working group selection

If a group name is selected then any modification that is done in this window will apply to the selected group only. Otherwise, if the “All” option is selected the modification will involve all the groups together (they are managed as a unique big group). In this last case a message is displayed before proceeding.

Figure 199 Confirm to continue

It is strongly suggested to check the “Current working group” every time before applying any modification to avoid an unexpected program behaviour.

Linear Group generation

The following group of tools are related to the creation of a linear array of electrodes. To define the group properties correctly it is necessary to specify some information, e.g. the length of the line, its direction, and its starting/ending point. The tools available in the window lets the user set all these parameters. There are more ways to set the necessary information, but the unset parameters are estimated by the program and displayed for the user benefit.

Figure 200 Linear group generation tool

• Electrodes - Count: specifies the number of electrodes in the linear group. It is related to the instrument used in the field, typically it is a number like 24, 48, …

• Electrodes - Spacing [m]: specifies the distance between electrodes. Only equally spaced arrays are accepted.

• Group Start - X[m]- Y[m] - Z[m]: specifies the starting point of the linear group in the 3D space. If the user desires to work in local coordinates it is often set to (0,0,0).

• Group End - X[m] - Y[m] - Z[m]: specifies the ending point of the linear group in the 3D space. If the user desires to work in local coordinates, Y and Z are set to 0 to have an alignment along the X axis.

• Dir X - Dir Y - Dir Z: specifies the direction of the line. It is possible to set only one of them at a time, but in special situations it is allowed to have none of them selected.

Because is it not possible to freely edit all the previous parameters together, the program helps the user to understand the derived values (highlighted with a grey colour) from the ones provided. For example, if “Count”, “Spacing”, “Group Start” and “Dir X” are specified, “Group End” is automatically computed.

Figure 201 An example of linear group definition. Derived values highlighted in the blue rectangle

When the information is provided, click on one of the following buttons:

• Insert: a new group will be created. The user will be asked for the name of the new group (it cannot be an already used name). The “Current working group” will be automatically set to the new group name to make future editing easier using the other tools available.

• Update: the selected group is modified to the linear array specified. It is only possible to use this tool, if a specific Group is selected. If “All” is selected as current working group then the button is not active. If any change of the current working group happens then the values shown in the current sub-panel are updated to fit the selected group features. If the selected group is not linear, the values shown will still be useful to get some important characteristic of the group, e.g. the number of electrodes. When the editing is finished the checkbox must be unchecked to disable the tool and to came back to the default window.

Continuous mouse append

This tool the user can freely add one or more electrodes to the selected group, using a single mouse click.

Figure 202 Continuous mouse append tools

When “Enable” is checked, the tool becomes active and a new window will appear (Figure 203). The main panel hides the other tools because they cannot be used at the same time and the window is locked on top of all the other windows to remind the user that this tool is active.

Figure 203 The Continuous mouse append tools is active

The new tools of the extended panel was already explained in this document in two places: the first one named “Continuous mouse append” is related to the method to add electrodes (section Append point using a picker) and the second one in the “Picker Tool”, which is related to the visibility of the mouse position (see section View Picker settings). The right approach to use this tool is to select the desired group that needs to be enlarged, then click on the 3D view with the right mouse button to add single electrodes (Figure 204). The electrodes are always added at the end of the group.

Figure 204 An example obtained with single click on every electrode to create in the group

It is possible to add more electrodes with a single operation editing the fields “Num” and “Step”, allowing the user to easily draw a complex layout with only a few mouse clicks (Figure 205.

Figure 205 An example obtained with few click

If the “All” option is selected as the “Current working group”, it will create a new group and the user is asked for a new group name.

Figure 206 Provide a group name

When the editing is completed, the checkbox must be unchecked to disable the tool and to came back to the previous window.

Modify current group

The following group of buttons are related to the modification of existing group(s).

Figure 207 Modify current group tools

Delete

Clicking this button the selected group will be permanently removed from the dataset; a confirmation box will be appear before proceeding.

Figure 208 Confirm message for “Delete” action

Clone

Clicking this button creates a new group exactly equal to the selected group. The name of the new group must be specified.

The new group will be not easily visible in the 3D scene, because the cloned group source is also displayed. Cloning a group is often not the final target, but a starting point to something more complex: for example, a cloned group can be moved easily to obtain parallel lines.

Figure 209 An example of a cloned group to obtain parallel lines

Flip

Clicking this button, the electrodes position in the group does not change, but the direction is reversed.

This can be easily verified visualizing the ID of each electrode in the group.

Figure 210 The blue group is the flipped version of the red group

This operation is useful to define the electrode geometry and IDs of each cable in the correct way, accordingly to the syntax needed by the instrument that will be used in the field.

Rotate

Clicking this button rotates the selected group. First, it will be asked for an angle of rotation (in degrees) in the range from 0 to 360.

Figure 211 It is needed to provide an angle of rotation

Then, the user will be asked for the rotation centre, which will be the barycentre of the group (by default, it is centred in X = 0, Y = 0).

Figure 212 It is needed to provide the centre of rotation

Figure 213 shows two rotations of 30 degrees; the red group is rotated using his barycentre to obtain the green group, or is rotated centring on its first electrode to obtain the blue group.

Figure 213 An example of group rotation

Scale

Clicking this button changes the size of the selected group. First, the user will be asked for the size ratio change, the default value is 1. A scale factor greater than 1 means that the group will be enlarged, a scale factor smaller than 1 (but greater than 0) means that the group will be made smaller.

Figure 214 It is needed to provide the scale factor

Then, the user will be asked for the centre point for the scaling operation. The message displays the default (X,Y) values, which are the barycentre of the group.

Figure 215 It is needed to provide the centre for scaling

Figure 216 shows two scaling factors applied: in the first example, the red group is scaled of a factor 2, using his barycentre, to obtain the green group. In the second example, the red group is scaled of a factor 0.5, using as centre point its first electrode, to obtain the blue group.

Figure 216 An example of the use of the “Scale” tool

Move current group

The following group of buttons can be used to translate group(s) of electrodes along the main axes.

Figure 217 Move current group tools

The names of the buttons refer to the axis along which direction to make the translation (the following images helps to understand the type of movement applied by each button).

Figure 218 An example of the four basic displacement that can be applied along the X/Y axes (A) and along Z axis (B)

The “Move amount” parameter can be used to set the amplitude of the displacement with each mouse click. The default value is 1 (meter), but it can be changed to move the groups of the desired step at once.

Remove Duplicated

Click with the right mouse button on the node “Electrode”, choose “Tool”, and then Remove Duplicated tool (Figure 219).

Figure 219 Tool Remove Duplicated

Through this tool it is possible to remove duplicate points, which are two or more measurements belonging to the same quadrupole. Duplicate measurements may originate from an electrode recorded by the topographer two times with a small difference or from two 2D lines which intersect each other not in correspondence of the same electrode.

Figure 220 Setting of minimum distance for duplicated electrodes

The “Min Distance” is the tolerance of the distance between two electrodes. At values higher than those indicated the electrodes are considered as two individual entities and at lower values the two electrodes are merged into a single electrode. At the end of the process a window will inform the user about the number of duplicated quadrupoles removed (Figure 221).

Figure 221 Skipped electrode message

Import

Click with the right mouse button on the node “Electrode”, choose “Tool”, and then Import tool (Figure 222).

Figure 222 Import electrodes tool

Through this tool it is possible to import electrodes. It is possible to load:

• XYZ file (*.xyz; *.txt);

• DATA file (*.data; *.wDat; *.txt);

• Google Earth file (*.KMZ). In this case the coordinates of the electrodes must be in UTM system.

Export

Click with the right mouse button on the node “Electrode”, choose “Tool”, and then Export tool (Figure 223).

Figure 223 Electrode Tools_Eexport

Through this tool it is possible to export a file containing the coordinates of the electrodes used in the loaded project. The exported file is a 3 column .txt file, as shown in Figure 224.

Figure 224 Part of electrodes exported file (X,Y,Z coordinates)