Tensor Research Newsletter
December 2024

More on Point Visualisation, AutoMag and QuickDepth

Here we show some examples using flexible data point annotation, AutoMag solution visualisation and QuickDepth symbols.

In the first example of point annotation, the symbols sizes and colour selections would not normally be used in this way, but they do demonstrate the level of control. Importing geochemistry data or rock property measurements can also be used in this way.

Point data are displayed as colour and size modulated symbols with colour = depth below ground, diameter = depth quality estimate. The title box in the left corner is designed to show the names of the channels and their relative locations. Annotations clockwise from left side are mauve for magnetic susceptibility (cgs), black for formation width (m) and white for depth below ground (m). Font size, decimal points, position and orientation are controlled for each annotation. The top image is RTP with RTP contours. The bottom image is a geo-registered JPG bitmap overlain by RTP contours with the point symbols as the top layer.

In the left-hand AutoMag example below, the conventional Smart points representing strike and dip directions are colour-coded by the Level number as the width of the sample data expands by a factor of 2. The right-hand image is using points generated via the Standard Points button on the AutoMag toolbar.

Left - AutoMag solutions as smart points with symbols showing tabular body strike and dip directions.
Right – Smart points converted to standard points using the trend direction as an arrow scaled by trend confidence.

QuickDepth-specific symbols have been included in this update along with other minor improvements. A further update for QuickDepth users is expected after release 18.0 is finalised. The example below shows how specific symbols have been used to have some resemblance to the body type (sheet, pipe, ellipsoid, edge) selected by the interpreter.

QuickDepth results from the tutorial training set based on a complete set of supported body types.
(a) 3D perspective view of the model and survey lines. (b) QuickDepth symbols with depth annotation.
(c) QuickDepth symbols and depths over the top of the original model. (d) QuickDepth symbols and depth annotations over the normalised source strength (NSS) image.

Genius Search AI Assistant!

The AI Assistant is a welcome addition to the learning process because you can ask it plain English questions and refine them as you go. In the previous example of a full text search, your question is more focussed on a specific outcome.

Here, I asked AI Assistant the question “Can I use FFT to transform total magnetic intensity grids to the magnetic tensor?”. In response, it gives you a summary of what it has found and a link to the most useful page in the documentation. There may be more than one link depending on the nature of the search.

Example of the AI Assistant being used to find references to the transformation of TMI to the magnetic gradient tensor.

Coding with the Calculator

Our calculator operates on lines, grids, points and drillholes along with a new and more powerful computational engine. Extended function list, logic branching and scripting allow you to build reusable code each time you receive a new survey dataset. This script is used to convert magnetic tensor data to commonly used parameters such as the analytic signal of the Bz component (ASz), invariants I1 and I2, Tilt angle, dimensionality (DI) and SI stands for shape index (Cevallos, 2014).

A multi-line script example applied to tensor data (BFnn) resampled from grids derived from a total magnetic intensity grid using ModelVision’s powerful suite of FFT tensor filters.

When finished, the calculator shows the last line in the script file. If bad syntax is encountered, it will stop at that line and provide an error message. Just update your MVP script text file, reload and Compute. Results of the calculation from one line over two magnetic pipes are shown in a Multi-Track view of 7 computed channels plus the original magnetic data. Note the symmetry of the ASz, Invariant 1 and Invariant 2 channels.

Multi-Track plot of Mag plus 7 computed data channels.

The IF statement allows you to include another cascading IF statement in place of a simple parameter or calculation. For example, say you have three parameters A, B, C, you can craft a multi-tiered expression where either output parameter can be replaced by a logical expression.

D = IF( A > B, C, A+B)
D = IF(A > B, (IF(A = NULL, C, A+B), A+B))
D = IF(A > B, (IF(A = NULL, C, A+B), (IF(A=B, C, A+B)))

While this is very powerful and efficient to use, it is difficult to spot logic problems and if you find you are having problems, break it out and create intermediate values that are used on the next line.

Reference: Cevallos, C. 2014 Automatic generation of 3D geophysical models using curvatures derived from airborne gravity gradient data. Geophysics 79 (5) p. G49-G58.

Turn data points into models

For researchers interested in studying large scale models, the point to body conversion tool has been expanded to include tabular, spheres, ellipsoids, circular and elliptical pipes. Test your survey specifications before you fly by simulation. It is now easy to create a model of near surface maghaemite nodules using randomly distributed ellipsoids or spheres along with your target model. You can build the full model point data in Excel or other applications such as Python or MATLAB which is much faster than creating the model manually using the Create Body tool. This example used a random noise generator to create the easting, northing, and elevation. Although not done here, you can also simulate random magnetisation directions and amplitudes. These models are used as a basis for testing different processing techniques and survey specifications for optimum data collection.

Lab measurements of density or magnetic properties can be converted to a located point set and turned into simple spheres that can be overlain on geological and image maps. At any time, you can convert the body to another body type and start modelling. If you have many samples, use the bodies (samples) in the RockMod module to assess their possible lithology classifications by overlaying the lab measurements on one or more of the charts.

A map view and zoomed 3D perspective view of a near-surface noise simulation using randomly distributed ellipsoids to emulate near-surface noise sources with random magnetisation directions immediately above manually positioned circular pipes.

Summary list of Improvements

Here is a summary of the major new features, improvements and fixes for bugs and awkward settings.

-------------------------------------------------- IMPROVEMENTS SUMMARY --------------------------------------------------

WEB-BASED DOCUMENTATION - We are moving to web-based documentation to provide a more functional experience with finding answers to questions. Full text search with Google-style reporting and an experimental AI Assistant. A full User Guide will be included with the final release along with a compressed HTML version of the online documentation (CHM). We will be able to make updates to the online documentation between releases.

GOOGLE-STYLE SEARCH OF DOCUMENTATION - Use Google-style full text searches to find more relevant links to resolve your questions. This is generally much faster than using the conventional search of the contents.

AI ASSISTANT (EXPERIMENTAL) - There is an AI assistant available for the online help that uses a cut-down version of a large language model that focusses on the ModelVision User Guide and related Tensor Research documentation.

DELETE MULTIPLE LINES INTERACTIVELY – Clean up messy line datasets using the Active line toolbar. Select tie

lines, duplicates and short lines from complex datasets.

CALCULATOR SUPPORTS CASE SENSITIVITY FOR OUTPUT - Mixed case output channel names are now supported for all calculator data types. This was part of a major rewrite of the underlying calculator engine.

STANDARD POINTS VISUALISATION - Improvements have been made to Point visualisation with new structural symbols, advanced annotations, size, colour, azimuth modulation and legends. The new Apply button allows you to test your settings before exiting the dialog.

BODY LABEL VISUALISATION CONTROL - The operation and capabilities of the body label dialog have been expanded to provide access to all the location, shape, density, magnetic and remanence properties of bodies visible in map and section views. A pull-down list of the property substitution parameters helps you select the most appropriate property names. Labels are better behaved when zooming or panning and you can now enter a specific font size instead of using the slider. A new Apply button allows you to test your changes before exiting the dialog.

CONTOUR CONTROLS - Improved decimation down to 1.0 for smoother contours, line thickness and heavy contours.

COLOURED CONTOURS WITH LEGEND SUPPORT - Coloured contours added with the option of including a legend that can be positioned anywhere in the map.

MODEL WITHOUT A DATA INPUT CHANNEL - A checkbox to define an input channel has been added so you can go straight to modelling without input data.

POINT TO BODY NEW BODY TYPES - Import from points supports body type for sphere, ellipsoid, circular pipes, elliptic pipes and tabular shapes.

POLYGONAL SELECTION TOOL - A polygonal area selection tool was added (right mouse access) to assist with body selection and body deletion. Useful when you have many bodies, especially from AutoMag and RPD Mapping.

ROCKMOD POLYGON BODY SELECT - Polygonal body selection added to focus in on specific target areas of a map. Especially useful with AutoMag, RPD Mapping imports and rock property measurements.

IMPROVED IMAGE RESOLUTION WITH BICUBIC INTERPOLATION - The default grid interpolation method is now set to bicubic instead of linear and this enhances the quality of images and image shading.

SPECIAL SYMBOLS ADDED FOR POINT DISPLAY - Several new symbols have been added to ModelVision for special point display that includes an azimuth modulation component. The arrow symbol is especially useful for AutoMag trends and RPD Mapping point import. This feature is very useful for a broad range of mapping and annotation of diverse point datasets.

POINT ANNOTATION IN MAPS - The annotation control dialog gives you more control over the position of multiple annotation around a point plus a new Apply button allows testing the display style. Very useful for rock property data, geochemistry, gravity QC and the display of our RPD Mapping property data.

POINT COLOUR LEGENDS - The colour legends for points now support discrete and continuous colour tables along with user-controlled ranges and annotation increments.

COLOUR LEGENDS WITH APPLY BUTTON - Colour legends in most cases have been upgraded to include continuous or discrete colour lookup tables (LUT) and control over the clipping limits and annotation increments. Body colours are restricted to discrete LUTs.

COLOUR LEGEND ANNOTATION INCREMENT - Most colour legends provide a control for the annotation increment that links to the range setting.

COLOUR LEGEND ROUNDING BUTTON FOR RANGE SETTING - For colour ranges where you can set the annotation increment, you can use the Round button to quickly reset the min and max values.

REMANENCE FLIPPING AT NEAR VERTICAL RESOLVED - Flipping of the direction of very steep remanent inclination during inversion has been resolved.

IMPROVED CONSISTENCY OF MAGNETISATION UNITS IN TKM FILE - Magnetisation units in TKM files so that they match the units (cgs/SI) shown in the magnetic properties dialog.

TKM MODEL EXPORT THETA - Theta section numbers used during modelling are now retained when exported to a model file to preserve the volume computation.

BODY LABEL NOW HAS AN APPLY BUTTON - The body label configuration dialog now has an Apply button and both this and the Apply to All Labels buttons keep the dialog open.

RECENT PROJECTS AND SESSIONS - The recent lists have been moved to a sub menu to reduce the total width and make navigation to your directory much faster.

BODY LABELS SLIDER CONTROL CHANGED TO FONTS SIZE - The body label size slider control was difficult to use and was replaced by a font size control.

MULTI-MAP CROSSHAIR CURSOR - A common crosshair will appear in all open maps when you select a point with the left mouse. Very useful for zoom and pan when maps are linked.

EXTERNAL RGB BITMAP IMPORT FORMAT FOR JPG, GIF & PNG - You can now use JPG, GIF and PNG files as well as BMP format files for sections and maps. PNG rendering is not always satisfactory.

GEOREFERENCED RGB MAP EXPORT - You can export your map view to a georeferenced image at a user-defined resolution. The EGB sidecar files contain the real world reference information and are compatible with PA Explorer and Datamine Discover. Future releases will support GeoTIFF and ESRI World formats.

DRILLHOLE BODY PROPERTIES - Completed new feature to sample body properties in a drillhole display. Sampling parameters are stored in the document so that each hole window has its own settings. These are retained in the session.

PROJECT INI FILE UPDATED DURING SESSION - Changes that you make to INI file related project parameters are saved during the session rather than just on exit.

PROJECT SELECTION NAVIGATOR - The project selection dialog has been expanded to provide more context and faster navigation.

PROJECT NAVIGATOR NEW PROJECT BUTTON - You can now create a new project from the Project navigator window.

AUTOMAG AND QUICKDEPTH MENU ENTRIES - Both moved to a single level access from the Modules menu.

AUTOMAG RUN ADDED TO SPEED TOOLBAR DIALOG - Quick access to the AutoMag Run Toolbar has been added to the Speed Toolbar when repeated quick access is required.

1D/2D SUMMARY FILTER LIST -ModelVision's 1D, 2D FFT and Convolution filters are summarised in a quick view table in the documentation. Make sure you check it out, especially the magnetic tensor list.

---------------------------------------------------------- FIXES SUMMARY ----------------------------------------------------------

GRID IMAGE ARTIFACT ON IRREGULAR BOUNDARIES - A dark contour appeared around the outer edge of an image adjacent to nulls. Introduced with smooth bicubic grid interpolation which failed to detect nulls beyond the data margin.

RESTORATION OF REGIONALS - Fixed problem with session restoration of some regionals where the most recent version in memory was not being applied.

LAYOUT WINDOW IMAGE DISTORTION - Image layers in the interpretation Layout Window drawing tool were distorted due to an image scaling problem.

MAGNETIC MODELLED COMPONENTS SELECTION - In the pull-down list for modelled components, Bzz was referred to as the Frist Vertical Derivative (FVD) and has been changed to dT/dz to refer to the FVD of TMI.

GINT FUNCTION RETIRED - The grid interpolation function has been retired with the new calculator. Use the menu option Utility > Sample from grid to create a data channel from a grid.

NSS COMPUTATION LINE FILTER - Fatal error resolved.

REGIONAL FIELD MAY NOT RESTORE CORRECTLY - When reloading a session file, a regional may not restore correctly when immediate mode is turned on.

DRILLHOLE DOCUMENTATION - The section on drillhole documentation was a draft version rather than the final.

POINT MODE FOR CALCULATOR - ModelVision crashed when trying to do any calculation in Point mode with the Calculator.

POINTS ANNOTATION FONT CORRUPTION - Font selection has been removed as an option due to issues with a low level graphics library. The low level software library does not support fonts in this mode so font control has been removed.

POINT MODE COLOUR STRETCH - When clipping the colour range, the top colour was not displayed correctly in the map.

SYSINFO - After Microsoft removed this function from Windows 10 in 2022, ModelVision would crash when inserting the info into the support email request.

ACTIVE POINTS IN SECTION VIEW - Previously required you to have a map view selected before you could set the active points in a section. The points can now be activated from an active cross-section window.

VERY LONG LINE IMPORT FAILS - Lines with more than 32,000 points caused the map window subsystem to crash when displaying the flight lines. These are now detected, and you are presented with options to subset or exit.

SMALL CONTOUR INTERVAL CRASH - Contour increments less than 1 with heavy contours could cause a crash.

REGIONAL MODIFICATION - When reopening a cross-section view that previously had a regional set, the regional was reset to an average fit.

RECENT PROJECT AND SESSION LIST - Moved to a sub-menu to declutter the menu selection process.

IGRF UPDATE - IGRF coefficients updated for the 2020 to 2025 epoch.

ACTIVE POINT POLYGON RESELECTION - When reusing an active point polygon in a map view, it did not activate the points until a refresh redraw is performed.

BODY LABELS ANNOTATION - Documentation referred to an arrange button. Removed in line with new capabilities for controlling annotation positions and sizes.

EXTERNAL RGB BITMAPS - If you have external bitmaps and they are not located when loading a session you can now navigate to the files or ignore them.

TK AND TKM/V7 MODEL FORMATS RETIRED - Reduce clutter in menus and documentation as we do not believe they are used any more.