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I work with engineering geology, and my workflow includes making many cross sections of a given site, with data from maps, fieldwork (outcrops) and boreholes.

What I'm looking for is a way of taking many cross sections and making a 3D model, with open source software, even with lots of (CAD) drawing work, but preferably with few code or programming knowledge.

So, when I first noticed this software (GSI3D), that takes many cross sections (actually a fence diagram) and gives, as a result, a 3D model, made of solids and not just surfaces, I thought it would be the perfect software. The image below is from the software website.

enter image description here

Given that I don't have the resources to buy it, I was thinking if there wouldn't be a free alternative (open source software) to this approach.

So I think the approach would be:

  1. Take the (CAD drawn) cross sections and combine them all in a GIS software, resulting in a fence diagram;
  2. Interpolate between all of the cross sections, resulting in surfaces, or even better, solids, each one representing a geological layer or lithotype;
  3. Make new cross sections between the former ones, to refine and adjust the model.

So, I think the 3rd step means that there is no need of a (very) complex interpolation algorithm, because the geological complexity would come from the cross sections, that are human made, not from the interpolation, that would be computer made.

The approach would be a first, simple, computer made interpolation, refined by manual adjustments.

To make it clearer, I'm not looking for a way of making a 3D geological model with complex interpolation algorithms to do all the work for me. I wouldn't mind having many iterations of cross sections to adjust and refine the 3D model, but I need a first (simple) interpolation so that I can work from it. The GSI3D approach seems to be it (I haven't used the software, but that's what I've understand).

I've read:

  1. Looking for a free program for 3D visualization
  2. Is there QGIS plugin to allow 3d visualisation of geological borehole data similar to functionality of Target for ArcGIS?
  3. 3D visualisation with open source GIS software
  4. Combining Geological Grids and extruding between them?
  5. a forum discussion
  6. a paper (this one looks good, but the author didn't uses GIS)

among other GIS sources, and it appears that GRASS would be the best choice, but the discussion (when using GRASS) seems to be always about an algorithm to do the hard work or using an expensive, proprietary software.

If the answer is GRASS, what would be the tools to do it (as I sad earlier, is there a way of doing it with just a few programming knowledge)?

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Mapalomalia can do that and it's free for public use.

What you are trying to do has problems when geometry changes abruptly or topology changes in any way. Most commercial software I've researched triangulates horizons from top to bottom, (or you have to pick them manually). However, you have to preserve topology, and have a close geometry. That's why they use the fences so in each cell the horizons are triangulable.

Mapalomalia can interpolate cross sections even when geometry changes fast or topology is different. You can see in the following blog article what mapalomalia can do: http://www.digital-geography.com/mapalomalia-first-web-geological-modeling-platform/. It's free for public geological modeling, that means the studies you create get shared with the public, but you retain ownership of them.

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Albion aims at providing an opensource software doing exactly what you want : 3D volume reconstruction from wells informations. It uses a specific method based on graphs for volume reconstruction. The software is based on QGIS and therefore allows for interaction with any geo-referenced data.

Albion is still in development, but a working version should be released soon, and software packaging and branding will come later this year.

There will be some remaining work to integrate Albion into the forthcoming 3D visualization capabilities of QGIS.

Do not hesitate to contact the project's authors on the github repository.

  • Could you add images of the software or projects made with it? – Marcos Saito Jan 9 '18 at 17:28
  • Our examples right now are private data which I cannot share for confidentiality reasons, but we will try to release the software at some point with a sample project with open data. Will let you know. – Vincent Jan 12 '18 at 17:11
2

Bit late to the thread but for others interest the British Geological Survey has developed stand-alone desktop software called Groundhog which would do what the OP requested and is available for under Open Government Licence for free!

It can be used to digitize geological cross-sections, and display and edit borehole logs, as well as supporting a range of baseline data such as geo-registered images and digital elevation models.

Groundhog Desktop Screen

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