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MGinv3D The program MGinv3D can be used to invert mag and gravity data to generate 3d models of susceptability and density. The 3d model uses voxels which are draped under the surface topography using triangular facets to give a good approximation of the surface. The program currently handles TMI, gravity and gravity gradient data. One thing to keep in mind when inverting data is that the resulting model can only be guaranteed to be feasible in that it will fit the observed data to the best degree possible. It does not guarantee that the resulting model is in any sense close to the actual geological structure. The utility of the model comes from how well it fits with known geology and how well the user can make inferences about the structure in areas where the geology is not known. This aspect of mathematics has a long history and I recently came across the following quote from Bayes (1736) which expresses it quite well: "It is not the business of the Mathematician to dispute whether
quantities do in fact ever vary in the manner that is supposed, but only
whether the manner of their doing so be intelligible; which being allowed,
he has a right to take it for granted, and then see what deduction he can
make from that supposition.... he is not inquiring how things are in
matter of fact, but supposing things to be in a certain way, what are the
consequences to be deduced from them; and all that is to be demanded of
this is, that his suppositions be intelligible, and his inferences just
from the suppositions he makes."
http://www.york.ac.uk/depts/maths/histstat/bayesbarnard.pdf Install Set Version 1.19 (21st March, 2012) Download the installer, double click on the downloaded file and the program will be installed on your system. When you run the install for the first time you should ensure that the Add application directory to your system path checkbox is turned on
This is the full install set for MGinv3D
This is the full install set for the experimental cluster controller
Update Log
Command line utility programs
Descriptions and sample datasets
General notes on UBC inversions (48KB)
Cluster Control for MGsen3D See this page http://msdn.microsoft.com/en-us/library/windows/desktop/aa389290(v=vs.85).aspx for information on setting up the WMI connections used by the cluster controller. This is a new tool has been added in version 1.19 to share the processing load for the mtx calculation across a number of networked computers. For the program to work you require: 1. The account for the computer on which the controller is running has to have the same logon name and password for all computers to be used 2. The account has to have Administrator privileges on all computers 3. Any firewalls on the computers have to be configured to allow WMI access using ports 135 (for RPC) and 445 (for MS Directory Server) 4. No unresolved networking issues (and from experience, these can be many and varied) 5. All drives and folders used have to be shared and read/write permissions granted to the users 6. Enable Remote Connections by starting the System applet from the Control Panel, then clicking on the Remote Settings item and turning on the Allow connections option for Remote Desktop (try both, but reboot after you make any changes) 7. Turn off the User Account Control settings or reduce them to as low a level as possible. (There should e some way to set the permissions for the remote logon to avoid having to turn off UAC, but I haven't figured this out yet) 8. For Windows 7, dynamic RPC ports have to be enabled for the WMI remote logon to work. To check if this is causing an error message of the form "Permission denied" when establishing the server connection, start the Control panel on the remote machine, start the Administrative Tools applet, start the Event Viewer, click on the Windows Logs and select the Security log. If you see a sequence of Audit Success events with Logon, Special Logon and Logoff, then it is probable that the remote machine is allowing the logon but not enabling the required ports for the RPC calls to occur. Instructions for fixing this can be found at the link: http://technet.microsoft.com/en-us/library/cc732839(v=ws.10).aspx NB this entails editing the group policy settings, so proceed at your own peril! You access the Group Policy Management Editor by clicking on the Start button, typing in Group and then clicking on the Edit Group Policy item and select the Windows Settings item, then the Security Settings item, then theWindows Firewall with Advanced Security item and expand it. Then click right on the Inbound Rules item, select New Rule and follow the instructions on the link above. If your computing environment satisfies these conditions, then you simply set up the inversion as usual, start the MGsen3D Cluster Controller program, add the computer names to the list of servers, select the drive and folder containing the inversion files and specify the drive and folder name to use for saving work files on each of the computers and then start the run. The program interface looks like this:
In this run the total time taken using 3 computers (XPS is a 4 core, 3.3GHz i7 975 desktop, StudioXPS is a 2 core, 2.5GHz Core-2 laptop and Precision 64 is a 2 core, 3GHz, Xeon 5160 desktop). The same run using the standard MGsen3D program took 13:45 minutes, while the total time for the clustered version was 9:16 minutes. This is a significant speed increase as the extra machines used are not exactly speedy. Indeed, the Precision64 should nominally run at about half of the speed of the XPS machine (about the same CPU speed, but half the cores) while in reality it only ran at about 1/4 of the speed of the XPS. Experimentation performed so far indicates that the reduction is elapsed time improves as the number of observed data points increases and also as the number of components used increases. It also improves as more servers are added. The same inversion run was repeated using just the XPS computer and the result was this:
This run slightly increased the total time taken (13:54 minutes vs 13:45 minutes). This shows that there is some overhead using the cluster controller. However the overhead is fairly small, so the extra information available from the interface mitigates the slight loss in performance even when using a single computer. Old Install Sets For Previous Version 1.19
Old Install Sets For Previous Version 1.17
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Send mail to
john.paine@onaustralia.com.au with
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