How can I smooth a geologic surface even if it doesn’t honor my data?

If I have surfaces that look like this with lots of peaks and troughs, is there an easy way to create a smooth surface, even if it doesn’t necessarily try to “honor” every point, more like a least squares fit? All of our estimation methods in krig_3d_geology honor your data, as best they can subject to your specified grid resolution.  The simplest way to get a smoother “apparent” surface is to coarsen your grid resolution.  However this method has some potential pitfalls, since the value computed at any give node will always approach the value nearest to that node.  This means that if one of your spike values (you can see that type of noise above) land very close to one of your coarse grid nodes, you can still get a spike in your coarse surface. However, there is an absolutely true way to smooth your surface regardless of grid resolution that is direct contradiction to my statement above (All of our estimation methods in krig_3d_geology honor your data). If you use the Advanced variography options in krig_3d_geology and set a non-zero nugget term, you can smooth your noisy data! I don’t have the customer’s dataset shown above, so I used one of our Sample Project datasets: This application has a DEM top surface, and a GMF file for the 4 additional stratigraphic surfaces.  After loading the app, delete these 6 modules: and after adding geologic_surfaces, change the Z Scale to 3.0 As you can see, the uppermost of our 4 surfaces is rather noisy (actually just accurately following this stratigraphic horizon, but good enough for this lesson!).   Right now we’re using Natural Neighbors with Gradients, which tends to give us the smoothest surface of all of our Estimation Methods that honors our data, but what if you wanted something much smoother? If you switch to Kriging, but don’t change anything else, you’d get: This is different, but not necessarily smoother (right)?  So let’s switch to Advance Variography and click on the Display and Edit Variogram button. To smooth our surface, we need to let the kriging DIS-honor our data.  The parameter that does that is the Nugget term.  For over 20 of our 29...

Free Mini Class on Advanced Visualization Techniques

C Tech will conduct a free mini-class on Advanced Visualization Techniques using Earth Volumetric Studio, on July 12, 2017 at 11:00 am EDT. We will cover some clever tricks with the buffer and union modules and some surprises.   The class was open to the first 50 registrants. It was posted Thursday June 22 and the final registrant was early Monday morning on June 26. The recorded video of the class is...

Fault Surfaces in Earth Volumetric Studio

There are normally two reasons to create fault surfaces in EVS.  We either just want to display them, or we want to use them to create fault blocks as part of a more complex geologic model.  When we create fault blocks, we are using the surf_cut module and the fault surface is input to the right input port.  There are three main cases to consider with respect to the creation of fault surfaces: 1) Planar surfaces.  A planar surface is a surface which is flat.  It can be oriented in any way, but is has no curvature, bumps, etc.  This type of fault if very easy to create with the create_fault_surface module.  However, you can also cut any 3D model using the “cut” module to create a fault block. 2) Non-planar surfaces created in EVS.  There are two cases here.  Single-Valued and Multi-Valued surfaces Single-Valued or simple surfaces can be created using krig_3d_geology, krig_2d or scat_to_tin using x-y-z points formatted as .GEO, .GMF or .APDV files.  This is the easiest way to create more complex surfaces which have only ONE Z coordinate for any X-Y location. Multi-Valued surfaces are surfaces which which have TWO or more Z coordinates for any X-Y location. Some simple examples would be a sphere or a tube (pipe). Some are easily created in EVS.  For examples it is easy to create tubes of constant or variable diameter with the tubes module, and these can be used to cut tunnels through geologic models. However, in general the creation of multi-valued surfaces is a very difficult process since traditional estimation methods such as kriging, IDW, splining, TIN, etc. cannot be used.  In some cases it is possible to find a coordinate transformation where the surface would not be multi-valued. For example, imagine a cross-section through a multi-valued fault surface below.  The red line shows where this surface is multi-valued.  If we rotate counterclockwise 90 degrees, this surface is no longer multi-valued and could be created using any of our traditional methods.  All we need to do is rotate the data, create the surface and then counter-rotate the resultant surface back.  We can rotate the data using transform_field, create the TIN (or...

Volumetrics Study: Studio vs. MVS

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...

Modeling of Karst Geology with Caves

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,...

Video on Cut-Fill Optimization in Studio using Python Minimization

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: