ERTLab Viewer

The ERTLab Viewer provides a user-friendly 3-D visualization environment capable of spinning the 3D model, viewing sections, planes, volumes, and shells with contouring and simple labeling.

1. Starting the Viewer

ViewerButton The Viewer may be started from the ERTLab Solver environment by pushing the viewer button of the main toolbar or selecting the menu item Tools > ERTLab 3D Viewer.

Alternatively the Viewer may be started from the Windows Start Menu by selecting the ERTLab Viewer icon.

The Viewer is also started automatically when the ViewMesh buttons are pushed from the ERTLab Solver Forward modeling workspace, Inversion Workspace or MakeMesh workspace.

2. Introduction to Controls

Like most MS-Windows software, the ERTLab Viewer environment is navigated using a system of menus or toolbar push-buttons.

MenusAndToolbars

2.1 Menus

In the system menu the following items are available:

File - Use the file menu items to open a file, to perform the printing tasks, to exit the program or to work with script files.
Scripts (saved and executed from the File menu) preserve information about point of view, zoom level, sections, volumes and shells displayed or available for display, color ranges and bitmap generation. Scripts are useful to preserve project views for future use and may be used to open new files using the same parameters that were prepared for a previous version of the model.

FileMenu

View - This menu item presents a list of toolbars which may be turned on or off (checked).

The Window button shrinks or expands the active window.

2.2 Toolbar controls

The toolbar provide access to the follwing tasks:

FileOpenButton Open file button.

ScreenCaptureButton The screen capture button permits capture of the document area of the active ERTLab Viewer window. The toolbars and menu are not included. A Microsoft format .BMP file is created at the resolution of the screen.

ProcessingToolMenu The printer button send the document area of the screen to any windows printer.

ProcessingToolMenu Click the post-processing toolbar  button displays a floating menu with visualization controls that will be described below. Click the button a second time to hide the floating menu.

SelectButton The select and interact InteractButton buttons work together to toggle the response of the mouse. The default is interact which provides perspective control over the model view. In interact mode the model is rotated, panned and zoomed depending on mouse clicks and movements. In select mode the mouse is pointed at an item on the screen. Left click results in display of a menu that permits some control over items displayed on the screen.

PerspectiveCheckbox The perspective checkbox toggles between perspective and orthographic displays. Perspective presents a more intuitive 3-D presentation and is the default. Orthographic presentation is good for 2-D section and plan views where distances will be measured.

XYZSnapButtons The X, Y and Z snap buttons orient the presentation so the viewer is located directly along the selected principal axis. This is useful for 2-D presentation of the model.

DefaultZoom The snap to default zoom button restores the initial zoom of the model.

SaveCurrentView Save current view provides the ability to save a particular perspective, zoom and rotation as a named view. The List of named views become available in the drop-down box to the right of the Save Current View button. To save a view click the Save Current View button and provide a name. To return to the saved view select the name from the list. Using the mouse, click on the arrow button to see the list.

ResistivityToggle The resistivity / conductivity drop-box toggles between resistivity (the default) and conductivity (= 1/resistivity))

POVButton Pushing the POV button displays the point-of-view menu which permits return to an exact view. This is useful when opening a sequence of files for the same model. On opening a new model the current views are lost, but may be recovered by recording the POV information.

POVMenu
The POV values are the coordinates of the viewer. These change when the model is rotated. The Focal point values are the coordinates of the center of the screen. These change when the model is panned. The View-up-Vector is the vector to the top of the screen. Changing these values changes the orientation of labels with respect to the Cartesian axes. The perspective distance provides an indication of zoom. When the perspective checkbox is off, this control may be edited.

2.3 Zoom, pan and rotate

To rotate using the mouse: left click and hold while moving the mouse.

To pan using the mouse: hold the shift key down, left click and hold while moving the mouse.

To zoom using the mouse:
hold both the shift and ctrl keys down, left click and hold while moving the mouse
or
right click and hold while moving the mouse.

3. Post-processing toolbar

The post-processing toolbar is used to control and modify the features displayed. On opening a model the electrodes are presented as red spheres and the model area isPostProcessingMenu enclosed in wireframe box. The post-processing control permits addition of sections, volumes, shells, control of the color bar, and addition and removal of axes, labels, color scale bar and the electrodes.

There are four areas of the toolbar.
The Main window shows items displayed and switches the feature control to the selected (highlighted) item.
The Vertical toolbar is used to add new items to the main window.
The Feature control area is specific to the selected item in the Main window.
The color range displayed applies to all objects and controls the distribution of the color palette.

  • In the main window, items currently displayed are checked POVCheck
     
  • Turn options such as color scalar bar, axes and electrodes on and off by clicking the associated checkbox.
     
  • The vertical toolbar to the left the of main window inserts SectionButton sections, isosurfaces Isosurface, volumes Volume and labels Label. Up to 10 of each of these features may be inserted. As each item is inserted it appears under the appropriate subheading in the main window on the toolbar. For example, one section is present in the toolbar shown here, no isosurfaces or volumes are present.
     
  • Each individual section, volume, etc. has its own check box that controls whether it is displayed or not. In addition, the entire suite of Sections, volumes, etc. may be turned on and off using the associated checkbox.
     
  • As each individual item is inserted (using the vertical toolbar) a sub-menu is presented.  This  is the same menu that is available after insertion in the feature control area. To adjust the feature controls first select the item in the Main Window by left clicking on it using the mouse.
     
  • To adjust the color range display change the min and max data visualization properties. The colors of the color bar are distributed across the min-display-max range. The min and max for the dataset are shown in the grayed out boxes to the extreme left and right of the data visualization properties area.
     
  • Feature controls that apply to the overall item suite are available by clicking on the main heading under visual items. For example, clicking on the section heading displays a contour menu in the Feature control area; and clicking on the Scalar bar heading displays a selection of linear or Log-10 and reversed color distributions.

4. Feature Control Menus

This section describes feature control menus that are displayed in the feature control area of the post-processing toolbar when master headings or individual items are selected by left-clicking on them using the mouse. Some of these menus are also displayed as individual items are inserted using the vertical tool-bar in the post-processing menu.

4.1 Scalar Bar feature control

ScalarBar

Two  color bars  are available in ERTLab, a typical rainbow distribution from cold, blues and greens through warmer yellows and reds, and the RB color bar from cold shades of blue through white in the center to warm shades of red. The controls labeled Linear, Log 10 and Inverted Linear control the rainbow color distribution and the controls labeled Linear RB and inverted Linear RB control the Red-blue color distribution. There is no Log 10 distribution available for the red-blue color bar.

To change the range of values over which the color bar chosen is distributed change the min and max displayed in the data visualization properties area of the post-processing toolbar.

ColorDistribution

4.2 Axes feature control

Axes

The Axis feature contol allows the user to change the location, length, and display of the Cartesion coordinate axes.   By default, the axis extend from the minimum to the maximu boundaries of the mesh in the X, Y and Z direction and contain labels and ticks at five locations. 

4.3 Electrodes feature control

ElectrodeSize

A slider bar that controls the size of the electrodes is available. To make the electrodes larger left-click on the slider using the mouse and drag it toward max.

4.4 Sections heading feature control

Click on the master sections heading to display the contour control. The default is automatic distribution of 32 contour levels.

Contours

To adjust contour levels:

  1. Click User defined
  2. Adjust the range of values over which the contours are distributed by changing the min and max displayed in the data visualization properties area of the post-processing toolbar.
    ColorDistribution
  3. Change the number of contours
  4. Press apply. The values will be automatically calculated.
  5. Any individual value may be changed by clicking on it once. The display of the value will change to a highlighted box. A known issue is that the value must be changed or the viewer will crash.
  6. Press apply after the values have been changed.

4.5 Individual Sections Feature control

Sections

- Each section must be assigned a unique name. The default is that each section is named sez1, sez2, and so on.

- Direction control is as follows:

  • XY is a plan presentation. Elevation of the plan is controlled by the Z position.
  • YZ is a vertical section in the YZ plane. X location of the section is controlled by the X position.
  • XZ is a vertical section in the XZ plane. Y location of the section is controlled by the Y position.
  • Vertical creates a vertical section. Position controls include centers in X and Y and an azimuth.
  • Any creates a randomly oriented section. Position controls are XYZ center of the section, and nX, nY, nZ control a perpendicular to the section plan. For example nZ=1, nX = nY = 0 creates a horizontal plan. nZ = nX = nY = 1 creates a diagonal from corner to corner of the model.

- Contour lines may be shown or not, contour values may be shown or not by using the mouse to check the boxes.

- Clipping on sets the colors outside the display range to white. Clipping off sets colors outside the displayed range to the hottest or coldest color as appropriate. Adjust the range of values over which the contours are distributed by changing the min and max displayed in the data visualization properties area of the post-processing toolbar.
ColorDistribution

- Mode provides three choices, the default is contours. Other choices are cell scalars and node scalars.

  • Contours threads contours between node values and provides a smoothly varying color scheme. This is usually the best presentation for typical inversion result (see i below).
  • Cell scalars assigns a single average value to each cell of the model. This presentation is used to visualize the resolution of the mesh and is more appropriate than contours or node scalars for models with sharply defined edges and boundaries such as a typically present in a forward model. This is usually the best presentation for a typical forward model (see ii below).
  • Node scalars smoothly distributes colors between nodes. It provides an alternative view to the smoother contours.
SectionModes

- The opacity control may be used to 'see through' the section feature.

4.6 Individual Isosurfaces feature control

Isosurfaces

- Each isosurface must be assigned a unique name. The default is that each isosurface is named iso1, iso2, and so on.

- The control produces a 3-D shell, which may be thought of as a 3-D contour, threaded to join the Iso-value chosen.

- The opacity control may be used to 'see through' the isosurface feature.

4.7 Individual Volumes feature control

Volumes

- Volumes may be named.

- A volume is created for the range specified. Since volumes may take some time to calculate, it is usually best to start with a small range, then expand it. One presentation we find informative is to create two volumes, one at the high end of the model range, and one at the low end of the model range.

- Adjust the range of values over which the contours are distributed by changing the min and max displayed in the data visualization properties area of the post-processing toolbar.
ColorDistribution

- The opacity control may be used to 'see through' the volume feature.

4.8 Individual labels feature control

Labels

- Labels may be named.

- The position, size and color of the label may be controlled.

5. Script controls

Script controls are used to save a model workspace for future viewing or to view alternative versions of the same mesh (some examples are: IP vs resistivity, alternative inversions produced using different parameters, or sequential periods of data collection).

To save a script select File> Save to script file from the File menu.

To run a script click File > Execute script file from the File menu.

To run a script changing the input mesh file name choose File > Execute script changing data... from the File menu.

A script file is an ASCII text file.The script file must comply with the following syntax:

The first line MUST contain the keyword FILENAME followed by the name of the data file.   
FILENAME \\NetworkComputer\Directory1\SubDirectory1\SubDirectory2\Filename.vwer
Following lines can contain any of the following keywords in any order, followed by the corresponding parameters in the given order. A line beginning with # is a comment (the first line, containing the FILENAME keyword, cannot be a comment). The supported keywords and the corresponding parameters are:

FILENAME "filename"
Specifies the data file name.
"filename" is a string containing the name of the data file.
SPLASHSCREEN t
Shows the splash screen (that cannot be automatically shown at startup since it would stop the execution of the script).
t is an integer value that specifies how long the splash screen will be shown in milliseconds.
SECTION "name" dir_x dir_y dir_z orig_x orig_y orig_z clip mode opacity contours contvalues
Inserts a section.
"name" is a string containing the name of the section.
dir_x, dir_y, dir_z are floating point values that specify the normal to the sectioning plane.
orig_x, orig_y, orig_z are floating point values that specify one point on the sectioning plane.
clip is an integer value that specifies if contours clipping is on or off (0 = off, 1 = on).
mode is an integer value that specifies the section mode (1 = contours, 2 = cell scalars, 3 = node scalars).
opacity is an integer value that specifies the opacity of the visual item (0 <= opacity <= 10).
contours is an integer value that specifies if contour lines are shown or not (0 = off, 1 = on).
contvalues is an integer value that specifies if contour values are shown or not (0 = off, 1 = on).
ISOSURFACE "name" isovalue opacity
Inserts an isosurface.
"name" is a string containing the name of the isosurface.
isovalue is a floating point value that specifies the surface's isovalue.
opacity is an integer value that specifies the opacity of the visual item (0 <= opacity <= 100).
VOLUME "name" min max opacity
Inserts a volume containing the subdomain in the range (min, max).
"name" is a string containing the name of the volume.
min, max are floating point values that specify the range.
opacity is an integer value that specifies the opacity of the visual item (0 <= opacity <= 100).
POV x y z
Specifies the point of view (POV).
x, y, z are floating point values that specify the point of view.
FP x y z
Specifies the focal point (FP).
x, y, z are floating point values that specify the focal point.
VIEWUP x y z
Specifies the view up vector.
x, y, z are floating point values that specify the up vector.
VIEW "name" pov_x pov_y pov_z focus_x focus_y focus_z up_x up_y up_z
Inserts a view in the view list
"name" is the name of the view
pov_x, pov_y, pov_z are floating point values that specify the point of view.
focus_x, focus_y, focus_z are floating point values that specify the focal point.
up_x, up_y, up_z are floating point values that specify the up vector.
SLEEP t
Inserts a delay in the execution of the script.
t is an integer value that specifies the delay in milliseconds.
SCALARBAR visible
Sets the visibility of scalar bar.
visible is an integer value that specifies whether the scalar bar is visible or not (0 = off, 1 = on).
AXES visible v_ticks v_labels v_titles ticks_x ticks_y ticks_z dec_digits r g b size
Sets the visibility of axes.
visible is an integer value that specifies whether axes are visible or not (0 = off, 1 = on).
v_ticks, v_labels, v_titles are integer values that specify whether ticks, labels and titles are visible or not (0 = off, 1 = on).
ticks_x, ticks_y, ticks_z are positive integer values that specify the number of ticks for x, y and z axes respectively.
dec_digits is a positive integer value that specifies the number of decimal digits shown in labels.
r, g, b are positive integer values that specify the color of axes (0 <= r,g,b <= 255).
size is a positive integer value that specifies the size of labels and titles (1 <= size <= 5).
ELECTRODES visible
Sets the visibility of electrodes.
visible is an integer value that specifies whether electrodes are visible or not (0 = off, 1 = on).
RANGE min max
Changes the scalar bar range to (min, max).
min, max are floating point values that specify the new scalar range.
FILTERS visible x y
Sets the visibility of filters dialog box.
visible is an integer value that specifies whether dialog box is visible or not (0 = off, 1 = on).
x, y are floating point values that specify the top-left corner of the dialog box (x and y are normalized to the main window's size and relative to its top left corner).
PERSPECTIVE on
Sets perspective on or off
on is an integer value that specifies whether perspective is on or off (0 = off, 1 = on).
LABEL "name" x y z r g b size
Inserts a label.
"name" is a string containing the name of the label.
x, y, z are floating point values that specify the position of the label.
r, g, b are positive integer values that specify the color of the label (0 <= r,g,b <= 255).
size is a positive integer value that specifies the size of the label (0 <= size <= 10).
CAPTUREBMP "filename"
Captures a screenshot in a bitmap file.
"filename" is a string containing the name of the bitmap file.
EXIT
Closes the application.
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