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faq-geomodeller

Geostatistics for interpolation of topographical surfaces is tricky because the assumptions of stationarity, smoothness and homoscedasticity that most geostatistical methods rely on (most form of Kriging) do not hold well in this type of environment. 

Deterministic interpolators such as spline regularized may work better when these assumptions are unverified.


In the case the 2d section view of modeled formations appear to be of low quality or inconsistent with the data, the most common causes are:

  1. Interpolation parameterization is incorrect, see https://intrepidgeophysics.freshdesk.com/a/solutions/
  2. Plotting resolution is too low, see below


You may improve it by increasing the Number of Node in the Plotting Resolution section of the Plot the Model Settings window. 

It is highly advised to chose the same value for the u and v Directions.



For example, here is a series of snapshots of the same exact sections at different Plotting Resolutions:




Geological contours may be digitized either as top or bottom on the topographical surface in GeoModeller. 

You may also import/export these contours into GeoModeller from various file formats such as .csv or .shp either onto a section (x,y) or directly into the model box (x,y,z).





It is possible to run the computation of the model on a subset of the model space.

Model Limits are set in the Global Parameters of the Compute the Model window. 




If you want to make a model deeper in extent and you want to preserve existing 2D sections and their associated contact and orientation data.

Steps:

  1. Close the project
  2. Open the .xml project file in a text editor (see below for details)
  3. Update the minimum depth (Zmin).
  4. Save the .xml file
  5.  Reopen in GeoModeller
  6. Reset the view if needed
  7. Recompute the model
  8. Save the project in GeoModeller

Example .xml file starting at


    <geo:Project3DEdit xmlns:geo="http://www.geomodeller.com/geo"    xmlns:gml="http://www.opengis.net/gml" author="rod paterson"    CoordSystem="GDA94 / MGA zone 54" date="23/ 6/2018 19:15:59"    deflection2d="0.001" deflection3d="1.0E-4" description=""    discretisation="1000000.0" precision="1.0"    projectName="NewCentury_Local_GM" unit="M" version="2.0">
      <geo:Extent3DOfProject>
        <geo:ExtentBox3D>
          <geo:Extent3D>
            <geo:ExtentXY Xmax="265000.0" Xmin="235000.0"    Ymax="7941000.0" Ymin="7910000.0"/>
            <geo:ExtentZ Zmax="350.0"        Zmin="-2650.0"/>
          </geo:Extent3D>
   


 Note that this will NOT change the depth extent of the vertical sections and they will remain as they were previously with all of the relevant contact and orientation data. The data for vertical sections is stored in UV coords referenced to the section extents and the vertical section geometry is contained in a separate .sec file. It is highly recommended not to edit these files.

The gravity forward modelling toolkit in GeoModeller provides either the Free air or regular Bouguer anomalies in the pre-computation wizard.



 Regional trends may be added in the post processing window after the computation has run, the tool proposes 3 options:

  • Constant: single scalar value
  • Linear: XY function + constant
  • Quadratic: same as linear + quadratic component




GeoModeller is able to run forward and inverse modelling for gravity and magnetics in 2D and 3D.

That is, it is possible to either:

  • Forward from a 3D grid (voxet) or 2D grid (section) to a modeled 2D grid or 1D line, respectively.
  • Invert from a 2D grid (observed) or 1D line to a 3D grid or 2D grid, respectively.


Forward modeling


In Geophysics, Forward modeling refers to the computation of the theoretical signal or response about a remotely measurable physical property for a specified body of rock.

A signal is obtained using passive survey methods while a response is obtained using active survey methods. The difference lies in the presence of a controlled human-made source used to force a response out of the surveyed area in the case of active methods. Physical properties may be measured passively or actively depending on the setting and equipment available.

For example:

  • Gravity is passive
  • Magnetics is passive
  • Electrical is active (IP)
  • Electromagnetics may be passive (MT) or active (airborne EM)
  • Seismics may be passive or active (reflected)


Therefore, forward modelling requires as input,

  •  a 3D geological model and,
  •  a set of measured or estimated values of the physical properties of interest for each formation

The 3D geological model and physical properties are then combined into an indexed 3D grid with physical properties.

The physical properties 3D grid is the basis for the Forward calculation of the theoretical signal/response along with the simulated survey parameters.

The forward modelling algorithm in GeoModeller will calculate the theoretical response of the modeled area based on all aforementioned data and settings.

In that sense, forward modeling can be seen as a geophysical survey simulation.


GeoModeller offers a range of forward methods:

  • 2D/3D Gravity (Bouguer, Free Air, Full Tensor, Gradiometry)
  • 2D/3D Magnetics (TMI, Gradients, Full Tensor)
  • 2D Seismic
  • 3D Geothermal (Temperature, Heat flow)


Inverse modeling


Geophysical inverse modeling refers to the computation of the physical properties of a specified body of rock based on observed data and, optionally, a geological model/constraints. That is, inversion is...the inverse of forward modelling.


Note that any type of inversion may only be run if an observed dataset for the corresponding property is provided

  • For 2D inversions, a 1D profile will constitute the observed data.
  • For 3D inversions a 2D grid will constitute the observed data.


Unlike forward modelling, inversion is non-deterministic because of mathematical ambiguities. Except for very specific cases, there is usually no analytical solutions for inversions and the process is solved numerically.

More specifically,

  • Starting from a "blank" physical properties grid, many forward models are built in successive iterations and compared to the observed data and geological model/constraints
  • The process measures misfit (how much a given forwarded model fits the data and constraints) and favors low misfit models over high misfit ones
  • Every iteration the inversion algorithm attempts to produce a model with a lower misfit until a stable state is attained. A stable state is reached when the misfit does not decrease anymore with successive iterations


GeoModeller offers two inverse methods:

  • 3D Gravity (Bouguer, Free Air, Full Tensor, Gradiometry)
  • 3D Magnetics (TMI, Gradients, Full Tensor)

GeoModeller uses a Top VS Bottom convention to determine the inside and outside volumes of a unit bounded by its geological interface. 

As geological interfaces are interpolated from discrete interface points, these may be either mapped as:

  • the top of the formation that it is attributed to
  • the bottom of the formation that it is attributed to

An immediate consequence of this distinction is that a "fill-up" formation is added either at the highest or lowest position on the stratigraphic pile where data for formation is missing by definition:

  • top referenced models have a default DefaultCover formation
  • bottom referenced models have a DefaultBasement formation


The Top VS Bottom distinction is set a the scale of the whole project, therefore either all interface points for all formations in all series map for tops or bottoms. It is not possible to work with a mix of both conventions.

When switching from one convention to the other, the same list of interface points mapped for the top of a basal unit will now correspond to its bottom. 

The volume fill direction is reversed when changing references. This will bring drastic change the geometry of the units and existing data may have to be reattributed to other units to maintain consistency across the model.


Below is an example of how much a reference switch alone may affect a vertical section.


The original model features a basin and an intrusion using Bottom reference with consistent structural data.



Reference switched version of the same model with no other changes, the intrusion is found at the top of the model as it is now modeled "inside out" and replaces the expected DefaultCover formation due to its Erode stratigraphic relationship.



Lithostratigraphic correlations sections may be broken down into individual columns and interpreted as vertical "drillholes" in GeoModeller provided that you know the location of each column. You may either model with or against the columns.

  • With: convert columns into drillholes and use them as data input to build the 3D geological model.
  • Against: build the 3D geological model without the columns, create dummy drillholes at their location and populate the geology from the model. Next, compare the results of the modelling to the columns and adjust the columns or model depending on which is more appropriate.





To export a GeoModeller 3D model to STL, you will have to export it as shapes via Export->3D Model->Shapes and select the STL file format.



GeoModeller is not available on Mac OS, and Intrepid Geophysics has no plan to make it so in the foreseeable future.


Users have reported success running GeoModeller on Mac OS using Windows virtual machines.


In GeoModeller, it is posible to export a computed model to a FEFLOW compatible smart layered mesh for use in watermodelling simulations.


To do so, go to Export->3D Model->Model



In the "Export Model" window, select Feflow in the 3D Export Types section



Carefully select the dz and VarZ values for optimal rendering of the target model.


Keep in mind that:

  • dz is the vertical cell size
  • VarZ is a downwards geometric/exponential expansion factor applied to dz


General guidelines are:

  • Start with moderate VarZ values (1<VarZ<2) to avoid stacking all layers at the very top of your model
  • Keep the dz value such that the number of vertical layers (cells) stays manageable in regard to VarZ
  • If the layers are stacking at the top, increase dz and/or decrease VarZ.

This can be performed by first exporting the TSURF (ASCII) file, from a built 3D geology model: 

  1. In GeoModeller, from the Main Menu: Export > 3D Model > Shapes
  • Choose Type: TSurf
  • Select: Create Archive File

2. Next, using a text editor to retrieve the TFACE VRTX: X,Y coordinates (Triangulated Face Vertex Nodes)

An example Tsurf file (ASCII) – exported from GeoModeller, showing which values need to be extracted to retrieve the x,y,z points data from the built 3D surfaces

GOCAD TSurf 1
HEADER {
name:_dfa_Surface_Blue
mesh:false
ivolmap:false
imap:false
*solid*color:0.109804 0.52549 0.933333  1
last_selected_folder:Graphic
}
#GEOLOGICAL_TYPE (one of:  boundary, top, fault, unconformity, intrusive, topographic)
#STRATIGRAPHIC_POSITION age_name age_time

TFACE

VRTX 1    10000.0    20000.0      -21.4

VRTX 2    10056.5    20058.1      -12.8

VRTX 3    10000.0    20074.5      -16.5

TRGL 3 2 1
TRGL 5 2 4
TRGL 2 3 4
BSTONE 1
BORDER 23  1 10
END


When attempting to compute a model, the following error message about one or more of the series in the stratigraphic pile may pop up.



This error message is triggered by an internal sanity check that verifies that every fault block in the model bears at least one interface point per series.


When computing a model, GeoModeller starts with the fault network and use the fault planes geometry to partition the model space into fault blocks. 

Series may only be interpolated based on the observed effect of those faults in terms of displacement vectors. 

If there is a lack of structural information in a fault block, it is impossible for the interpolator to draw the interfaces.



In this case, it is recommended to compute the model on Faults Only mode and then use the computed fault network model to determine where structural data is missing.



  1. Make sure the 3D model has been computed (Model->Compute->OK) and rendered (Model→Visualize 3D Formations and Faults→OK).
  2. Go to Project→Export 3D PDF→Select options→OK 
  3. Use Adobe Acrobat Reader to visualize the 3D PDF, other viewers are not supported


NB: drillholes are included regardless of whether they are rendered first. 


  • Constant elevation is measured against sea level.
  • Drape/Clearance is measured against ground surface.

This distinction is of importance when one aims to simulate the theoretical response/signal in airborne geophysics.



In the left Project Explorer pane you may right click an existing fault and select Attributes:



The Fault Properties window will show up. In this window, under the Range section, tick "Finite" for the Range of the fault. 

You will then be able to define the Horizontal, Vertical and Influence Radii along with the Centre.

Here, we are actually defining the boundaries of a spheroid that is used to clip the fault plane and apply a smoothing factor to the fault's displacement function.





To output GeoModeller 2D Viewer images:
 1. Make active the 2D view you require, by selecting it with the mouse
 2. From Main Menu, select: View→2D Viewer: (name of active section) > save image ... (select the file type .gif, or .jpg)
 3. Name the output image (File name:), and select the output directory (Save in:)
 4. Select "Save"


To output GeoModeller 3D Viewer images:
 1. Make the 3D viewer active, by selecting it with the mouse
 2. From Main Menu, select: View→3D Viewer→save image as (select the file type .gif, or .jpg)
 3. Name the output image (File name:), and select the output directory (Save in:)
 4. Select "Save"


  • Drillhole intervals are required to be consistent with the stratigraphic pile modelling reference (Top vs Bot).

  • Top and bottom stratigraphic pile modelling references are project exclusive, it is not possible top mix references types in your data.

  • When modelling on bottom stratigraphic pile modelling reference, the lowest interval in a drillhole is open. Therefore, it may not be computed as expected as information is ambiguous. At least one foliation and one contact point must be added to ensure that the lowest interval is appropriately integrated in the model.

  • Drillhole intervals may be set to a "relaxed" state to allow for some contacts to be ignored by the modelling engine should conflicts arise.

  • Regardless of the drillhole intervals state of relaxation, discrepancies between the intervals and other data may results in models that do not honour the intervals perfectly. This is due to the nugget effect of the variogram used to parameterize the the co-kriging interpolator. Nugget effect may be lowered by several orders of magnitude to constrain the modeled surface better (Model->Compute→Select Series in list->Parameters→Nugget Effect).


GOCAD  Tsurf surfaces use a positive downwards spatial reference, surfaces will then appear upside down in GeoModeller's 3D viewer.


To fix this, add ZNEGATIVEDepth to the header of the Tsurf file and reverse the z sign for all nodes (VRTX).


  1. In the Project Explorer pane on the left, go to Grids and Meshes→Import→Triangulations.
  2. Browse to the DXF file and open.
  3. In Grids and Meshes, expand the new mesh.
  4. Go to Nodes→Field Visualisation Manager.
  5. Tick-on View Grid in 3D and View on Section where needed.
  6. Render the sections of interest in the 2D viewer and digitize manually.

  1. Go to Section→Topography→Load from DTM.
  2. Browse to the DXF file.
  3. Import.  


Project extents update in GeoModeller is not officially supported.

A full backup of the project is recommended prior to undertaking any of the steps described on this page.

The procedure is as follows:

  1. Go to Project→Save Batch Scripts..., enable all options and select the Output Directory and File Name.
  2. In the Navigator pane on the left side, browse to your project directory and double click the .task file generated in the previous step. The content of the file will appear in a new tab.
  3. Edit the Extents attributes to fit your needs. Note that structural data which may be left out of the new box will not be removed automatically.
  4. Save with Ctrl + S.
  5. Click on the black down arrow next to the green play button on the top icon row and select Run Configurations.
  6. Browse to the task file and click Run.
  7. Close the project and open its resized counterpart.


GeoModeller runs on most modern x86_64 PCs or workstations. 32-bit platforms are no longer supported.


CPU


Intel / AMD x86_64 processors which support AVX instruction set:

  • Intel Sandy Bridge (introduced Jan 2011) or newer;
  • AMD Bulldozer (introduced Late 2011) or newer, recommend Ryzen 5 or Ryzen 7;

To use the embedded Intel HD graphics, Intel Broadwell CPUs (introduced Jun 2015) or later is a must.


Memory


8GiB minimum, recommend 16GiB or more, depends on the scale of user's data sets.


HDD


This depends mainly on the size of user's data sets. GeoModeller itself requires at least 2GB disk space.


Graphics Card


nVidia does not support OpenGL over Microsoft Remote Desktop protocol on its GeForce product line.
To run our products on a remote computer using RDP, use nVidia Quadro series or AMD products.

All graphics cards supporting OpenGL 4.3 and above, with the latest driver from the vendor, are supported.

Including:

AMD Radeon HD 57xx or newer, introduced in late 2009;

nVidia GeForce 400 series, Quadro M, P, V series or newer, except GeForce 405;

Intel HD Graphics 7th Gen or above, seen on Intel i3, i5, i7-5xxx, 6xxx, 7xxx CPUs.


Operating System and Other Software

64-bit Microsoft Windows 7, Windows 10, preferably Professional or Ultimate. GeoModeller may run on Windows 8 / 8.1 but not officially supported due to the lack of support from the OS vendor (Microsoft).

GeoModeller currently supports Windows platforms.  We have the Linux version running in-house. Please contact us for available versions.


Adobe Acrobat Reader DC for documentation viewing, and it needs to be the system default PDF reader.


  1. Uninstall any other version of GeoModeller.
  2. Close all other applications.
  3. Update drivers.
  4. Update OS.
  5. Turn off antivirus software.
  6. Go to C:\Users\<your_user> and delete the .geomodeller directory.
  7. Upgrade hardware to required specifications.


Go to Help→Release Notes


Category
Data type
Resource type
Description
Grids and Meshes
Voxet
GoCAD Voxel Model
 
 
Triangulation
BREP
 
Drillholes
Three Table Drillholes (Collar, Survey, Geology)
Plain Text
 
 
Seismic Navigations
Plain Text
 
Seismic
Seismic Horizons
Plain Text
 
 
Orientations Projected onto Sections
Plain Text
 
 
Orientations
Plain Text
 
 
Observations
XYZ
 
 
Micro-Seismic Flow Data
Plain Text
 
 
Micro-Seismic
Plain Text
 
 
JetStream
 
 
 
Interfaces Projected onto Sections
Plain Text
 
3D Data
Interfaces
Plain Text
 
 
Interactive Inversion
 
 
Others
GIS and Binary Located
Intrepid Dataset
 
 
GeoSciML
XML
GeoSciML XML
 
Dykes w/ Topography as Depth Reference
 
 
Topography
Digital Terrain Model
Arc Grid
Common from SRTM
 
BRGM GDM
Plain Text
 
 
BRGM ASCII
Plain Text
 
 
Assays Data Merged into Existing Drillholes
Plain Text
 
 
Apparent Dips
Plain Text
 
 
2D Grid
Intrepid Grid
 
 
2D Data
MapInfo
 
 
 
GeoTIFF
Common from SRTM
 
 
Semi Grid
Simple Ascii
 
 
ERMapper Grid
Common in Australia
 
 
DXF wireframes
Converted to 2D grids on the fly
 
 
Geosoft Grid
 
 
 
NetCDF (GMT) Grid
 
 
 
NetCDF (DODS / DAP) Grid
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
Text Voxel Model
 
 
 
AutoCAD DXF
 
 
 
GoCAD
 
 
 
Vulcan
 
 
 
Generic Data
 
 
 
CSV
 
 
 
F/ Intrepid Dataset
 
 
 
GoCAD Voxel Model
 
 
 
Text Voxel Model
 
 
 
Geosoft Grid
 
 
 
Semi Grid
 
 
 
GXF Grid
 
 
 
ASCII Arc Grid
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
CSV
 
 
 
ASCII
 
 
 
XYZ
 
 
 
LAS
 
 
 
MapInfo
 
 
 
MapInfo TAB
 
 
 
ESRI Shape
 
 
 
BRGM ASCII
Geomodeller Section Data



Category    
Sub-category
Data type
Target resource    
Compression
Description
2D Data (Data on a section)
 
Geological Contact Points
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Orientation
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Section Trace
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Drillholes
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Geological Contact
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Geological Polygon
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
 
 
Potential
MapInfo (.mif, .mid)
No
 
 
 
 
BRGM ASCII (.data)
No
 
3D Data
 
Structural Data
XYZ (.xyz)
No
 
 
Drillholes
Drillholes
GeoSciML (.xml)
No
 
 
 
Drillhole Assays
CSV
No
Research
3D Model
 
Inversion Voxet
 
No
 
 
 
Section Interfaces
 
No
 
 
Faults
 
Earth Vision
No
 
 
Interfaces
Seismic (Depth Converted)
??
No
 
 
 
??
VRML Project Website
Yes
 
 
Shapes
 
TSurf
Yes
 
 
 
 
Vulcan
Yes
 
 
 
 
STL ASCII
Yes
 
 
 
 
DXF
Yes
 
 
 
 
IGES
Yes
 
 
 
 
STEP
Yes
 
 
ISATIS
 
 
No
Research
Grids and Meshes
Grids and Meshes
Observations
XYZ (.xyz)
No
 
 
 
 
Generic Data
No
 
 
 
 
Intrepid Grid
No
 
 
 
 
Semi Grid
No
 
 
 
 
Noddy Model
No
 
 
 
 
UBC Voxet
No
 
 
 
 
GoCAD Voxel Model
No
 
 
 
 
Text Voxel
No
 
 
 
 
GXF Grid
No
 
 
Field Data
 
 
No
 
 
 
 
Iso Surface
No
 
 
 
 
Iso Volume
No
 
Geology
 
Formations
CSV
No
 
 
 
Dykes
CSV
No
 
 
 
Faults
CSV
No
 
Topology
 
Topography
Intrepid Grid
No
Research
 
 
 
Geosoft Grid
No
Research
 
 
 
NetCDF (GMT) Grid
No
Research
 
 
 
NetCDF (DODS / DAP) Grid
No
Research
 
 
 
Semi Grid
No
Research
 
 
 
GeoTIFF
No
Research
 
 
 
JPEG
No
Research
 
 
 
PNG
No
Research
Model
 
Isopachs
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Isohyps
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Interfaces
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Layer-cake
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Marthe
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Tough2
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Voxels
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Gradients
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
 
 
Tough Voxels
Geosoft Grid
No
Research
 
 
 
ASCII Arc Grid
No
Research
Others
 
Inversion Depth
 
No
 


GeoModeller is supported for Windows 7+ versions only. Older versions of Windows might be able to run the software but that is not guaranteed.

The installation process for GeoModeller is straightforward:

  1. Download the latest public release of GeoModeller available here
  2. Double click the .msi installer
  3. Review the licensing terms and installation notes
  4. Customize the installation path according to the installation notes
  5. Include the VC++ Redistributable Package if this is your first install