Volumetrics Study: Studio vs. MVS

Jan 18, 2017 in Tips and Tricks, Training

Prior to the formal release of Studio, we did a comprehensive volumetrics study because we were making significant changes to both volumetrics and subsetting (e.g. plume) modules in Studio.  In that study we looked at our new Studio algorithms compared with MVS as a function of grid resolution. We’ve always known that as you increase the resolution of your model, the accuracy improves and we always see volumetrics results approach an asymptotic “theoretical” value as the grid resolution is increased. Our new algorithms in Studio work dramatically better than MVS, but we didn’t make a big deal about it, primarily out of concern that by saying that Studio is much better, we could be misconstrued as saying that MVS was somehow WRONG before.  In reality, everything we do (and by reference, everything you do with our software) is geostatistical by nature.  It is a best estimate.  And usually it is only a fair estimate because of data quality. In our study we focused on Chemical Mass (not plume volume) of the entire model, as well as X, Y, Z CG and Average Concentration.  If you additionally consider subsetting (plumes) they will effectively decrease the model resolution since the subset upon which you are computing volumetrics is a portion of your total model that has a lower effective resolution.  The higher the subsetting (plume) level, the lower the effective resolution and the poorer your results may be. The tables below summarize our results which are also given as graphs.  For both Studio and MVS we did the calculations with and without Adaptive Gridding (AG) for the total number of nodes ranging from 30,000 to nearly 8 million.  For all cases, we are computing volumetrics on the entire grid without any subsetting.   Both Studio and MVS reported exactly the same volume for the full grid which was 350,950 cubic meters.  This was not affected by resolution nor by adaptive gridding. In our study, there were very minor if any differences in volumes or plume volumes between Studio and MVS.  The biggest differences seen were in the computation of Chemical Mass and those parameters derived from chemical mass. The first, and perhaps most surprising observation of our study is how little impact (improvement) Adaptive Gridding makes for either MVS or Studio.  Adaptive Gridding does ensure that the data extremes in your 3D gridded output will better match your input data, but with respect to improving volumetrics accuracy, your time is better spent kriging a finer grid than waiting for Adaptive Gridding to finish.  The reason for this is that Adaptive Gridding refines the grid in localized areas around your data samples, but does not improve the grid globally.   As you can see, the Studio volumes are always higher than MVS, but are within 1-2% of the asymptotic value at virtually all grid resolutions.  For MVS, the volumes can be 20-25% low when the resolution is too coarse, but both Studio and MVS approach the same solution at high resolutions.. Average Concentration is derived from Contaminant Mass, and therefore is equally affected by the differences in accuracy as can be seen in the graph above. The three graphs below show the deviations in the CG or centroid of the contaminant mass in X, Y and Z.  A similar affect is seen here where Studio is markedly better at...

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Modeling of Karst Geology with Caves

Jan 17, 2017 in Tips and Tricks

One of C Tech’s distributor’s in China asked us to explain how Earth Volumetric Studio could be used to model Caves. The most straightforward approach is to use indicator kriging (e.g. indicator_geology module) and treat the cave as as if it were another material in the site lithology.  The video below takes this approach.  You can also apply adaptive_indicator_kriging to stratigraphic geologic models.  In this way, if you have a site with stratigraphic geology, you can include a cave based on lithology data within the stratigraphic layers. Other approaches are to model the cave as a volumetric excavation within any type of 3D volumetric grid using either: Binary lithology (values of 1 inside the cave and 0 outside the cave).  You would format the binary data as an APDV or AIDV file and use krig_3d (turn off log processing),  or Using a closed surface created outside of Earth Volumetric Studio (such as LIDAR) and then using surf_cut I hope that this instructional video will be helpful.  The application shown here will be included in the next release of Studio Projects. Reed D. Copsey,...

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Video on Cut-Fill Optimization in Studio using Python Minimization

Dec 2, 2016 in Tips and Tricks

We have posted a new Tips & Trick on Cut-Fill Optimization in Studio which uses a Python script to quickly converge on the optimal elevation for an excavation surface so that the amount of fill needed exactly matches the amount of material that is cut. The video is here:  

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Displaying Continuous Data

Apr 30, 2013 in Tips and Tricks

This Tips and Tricks video covers alternative options for displaying continuous data in MVS using post_samples and field_math.  

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Projecting Water Tables to 2D Cross Sections

Feb 6, 2013 in Tips and Tricks

This Tips and Tricks video covers the process for adding a water table surface to a 2D Cross Section. It covers how to properly project the water table surface onto a straightened thin_fence module. The applications created for this tip and trick may be downloaded here: thin-fence_water_table-to-2d_start.v...

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3D Fence Diagrams Projected to Two Dimensions

Oct 26, 2012 in Tips and Tricks

We’re pleased to announce a two part series covering the creation of 3D Fence Diagrams and projecting them to two dimensions. Part One covers the creation in EVS/MVS and Part Two covers the specific tasks required to export as shapefiles and create a publication ready 2D cross-section in ArcGIS Desktop’s ArcMap. Part One: Creation of Fence Diagram in EVS and MVS: Part Two: Exporting Fence Diagram to ArcGIS Desktop   The application created by the end of Part One may be downloaded here: Fence-diagram-projected-to_2D.v...

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Time Domain Animation of Surface Data

Aug 24, 2012 in Tips and Tricks

In this episode of our Tips and Tricks, we’ve provided a video tutorial which covers the preparation of data and EVS/MVS applications to perform animation of time domain surface data such as water tables and ground subsidence.

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Array of Slices in MVS

Feb 2, 2012 in Tips and Tricks

In this episode of our Tips and Tricks, we’ve provided a video tutorial on how to create arrays of slices.  Instead of using multiple slice modules, each of which creates only a single slice, we’ll demonstrate a method to create any number of parallel slices perpendicular to the x and/or y axes. Instead of using multiple slice modules, each of which creates only a single slice, we’ll demonstrate a method to create any number of parallel slices perpendicular to the x and/or y axes. The files used by this video include: x-grid_objects.v y-grid_objects.v grid-slice.v...

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Isolines In Depth

Dec 8, 2011 in Tips and Tricks

We get quite a few questions about isolines, usually about how to adjust properties.  In this post I want to cover some important features in isolines as well as how to get the most out of this important module. The isolines module in EVS-PRO and MVS is very sophisticated and has some features we haven’t seen in any other product.  A series of contours are generated for you between your data min and max.  For linear data (not log processed) that is normally “n” (# of Isolines) equally spaced contours between two bounds.  You can also override the bounds so that they are a subset of your actual min/max. Please note, it is not always possible to have a contour AT your data min or max.  Creating contours requires that you have some data both above and below the desired contour level.  One way to understand this is that your max value may occur at only a single point (node) in your grid.  A countour around (or at) it would have no area. If your data is log processed isolines does a more intelligent job of positioning the contours.  The “# of Isolines” slider (defaults to 3) sets the number of contours per DECADE.  That means that for the example below with a min of 0.001 (log = -3) and max of 80999.184 (log = 4.908), there will be nearly 8 decades of range to this data.  In other words, the data spans nearly 8 orders of magnitude (Max/Min ~ 100 million).  This means there will be roughly 24 contours, though that number can vary a bit depending on your min and max.  This is because the contours will be spaced roughly equally in log space and will always include even decades (e.g. 0.01, 100, 10000). The settings above with this application will give us the following isoline contours. So now let’s use some of the more advanced features of isolines.  Sometimes our isolines will stand out better on our surfaces if they are not colored. We’ve turned off the “Color Lines” toggle and set the Default Color to be a medium gray. One confusing/troubling issue with isolines is that they are drawn as LINES.  Unlike a triangle which has area and gets bigger as you zoom in, lines are drawn in pixels.  A one pixel wide line will APPEAR wide when your viewer is small (as the pictures above), but as you zoom in the width of those lines will not change.  This makes the lines seem thinner when the image resolution is high.  Below is the same settings zoomed in. In this situation there are two ways to make the lines wider.  The quickest is to edit the properties of the isolines.  You normally do that by first selecting the isolines “object” in the Viewer and then go to Editors…Object…Advanced_Settings. If isolines are your only line object, OR if you want all line objects in the Viewer to be wider, you can actually skip the step of selecting the object.  If you do, you’ll be changing the properties of all line objects. I wouldn’t be thorough if I didn’t mention the other way to make “wide” lines.  The tubes module can be connected to the blue-black output of isolines and will turn your lines into tubes.  Tubes are drawn with...

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Plume_Shell vs. Plume_Volume

Jul 29, 2008 in Tips and Tricks

This tip will explain the differences between the new plume_shell and plume_volume modules. Understanding the important differences between these modules can significantly improve your visualizations.  Primarily, the output from plume_shell is a hollow shell and the output from plume_volume is a volume of solid cells.  Plume_volume provides a volumetric subset of volumetric input data.  It should normally be used only if you plan to have other modules connected to its output.  If the end goal is only visualization, you should normally use plume_shell which should be connected to the Viewer. In the image below there are identical plumes displayed using plume_shell and plume_volume. The plume_shell on the left has a much smoother surface. Image 1 – Default settings for plume_shell and plume_volume To make the plumes look identical, select ‘Remove Normals Generation’ from each of the plumes. Image 2 – Remove Normals Off To display transparent plumes, the most visually appealing image is usually plume_shell with the Culling Mode set to normal (off) (Image 4D). The plumes below are shown at 50% transparency. Image 3 – Culling Mode still on (default) Image 4 – Culling Mode off Finally, plume_volume is necessary to show a slice through a plume. As shown in Image 5, slices through plume_shell are only outlines of the plume. Image 5 – Slices through plume_shell and plume_volume Hopefully these images demonstrate that plume_shell should be used when possible as the surface of the plume generally looks smoother. Networks using plume_shell will also be faster than networks using plume_volume. Generally whenever the objective is additional subsetting or volumetric operations on the output plume_volume should be used.  For example, you can cut, slice, further subset (E.G. on an additional dataset using plume_volume) the output of plume_volume.  However, since plume_shell is only a shell, most subsequent subsetting will not provide the desired...

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