Talk:Electrical resistivity tomography

Description of the technology

Hi, has anybody noticed that in the article there is NO description of how this technolgy works? It not specified what the electrodes are used for, what is measured, and how measurements are used to reconstruct the image. There is an history, a comparison with other techniques, but no way to know how this particular method work. I think the article has to be rewritten completely. Squalho (talk) 09:57, 9 October 2009 (UTC)

I entirely agree. Further, the applications of this technique (and thus the answer to "why we use it") are only briefly stated, as in finding faults and determining soil moisture, "etc.". "Etc." is not good enough; there needs to be a section devoted to applications of this technology and "electrical prospecting." Overall, the article is a hodgepodge, with minimal organization and no conceptual hierarchy. It's another WP "article" that makes you wish you had never looked it up.--Quisqualis (talk) 01:04, 28 December 2016 (UTC)

Change name/Move article

Hi, I'm wondering if "tomography" is the correct word. I've learned that researchers are now swinging towards "imaging" or "imagery" (e.g., ERI). This shift is due to:

1. Making the technology sound less jargony
2. The strict Tomographic reconstruction is very different to inversion techniques used in this geophysical method

Any thoughts?+mwtoews 18:20, 31 January 2007 (UTC)

I work in the mathematics of ERT but I am more familiar with medical and process applications. Indeed Tomography is a misnomer but one that has stuck. Also resistivity imaging could include surface resistivity mapping, a somewhat different technique giving no depth information. I suggest keep the name but mention the issues about the nameBilllion 10:20, 17 February 2007 (UTC)

Part of the motivation in this move is to build a bit of a Geophysical imaging article (it's fairly immature at the moment). Both "geophysical imaging" and "geophysical tomography" are used, and the former is 4× more common than the later term, according to Google search. Similar contrasts are "seismic tomography" vs. "seismic imaging" (I've also proposed that move, see Talk:Seismic tomography). It would be simpler to reserve "tomography" to medical imaging-related articles, and "imaging" to geophysics-related articles. I've noticed this shift in the geophysics literature, so I know I'm not completely out to lunch on this proposal. +mwtoews 21:16, 17 February 2007 (UTC)

I don't think google hits are a good guide here. What about the use of the terms in scholarly articles? And are they really being used for different things? Billlion 21:59, 17 February 2007 (UTC)

I've read several geophysics-related articles that mix the two terms in a single article, or worse: "electrical resistivity tomography imaging". Both "imaging" (ERI) and "tomography" (ERT) are used to describe the same geophysical technique, and there is no consistency of terms that I am aware of in both literature and technology (e.g. see AGI's website). The geophysics literature does not formally state that either term is correct or incorrect, nor are any difference pointed out. However, as I mentioned before, the data acquisition and inversion techniques used in geophysics are very different than used in medical imaging, and I've known researchers that have switched the term from ERT to ERI on the basis of these differences.+mwtoews 22:43, 17 February 2007 (UTC)

Oh, I found a few differences. This article attempts to point out the differences: "ERT (Electrical Resistance Tomography) is a method of obtaining resistivity measurements that determines the electrical conductivity of the ground using subsurface electrodes.7 In contrast, a multielectrode array uses electrodes only on the surface. Electrical Resistivity Imaging (ERI) is a general term used to indicate that an electrical resistivity technique is being used without naming each electrode configuration differently. An ERI image is an inverted model of hundreds to thousands of 4 electrode resistivity measurments. Hundreds of measurements of a site are required to produce a 2-D or 3-D ERI model of the subsurface". So in this essence, ERT is a method, while ERI is a technique (?). Meanwhile, this article (which mixes the terms) claims that ERT is a technique, while ERI is the result of the inversion. +mwtoews 22:56, 17 February 2007 (UTC)

I think you misunderstood me on medical imaging. Of course the inverseion is different from eg X-ray CT, what I mean is medical EIT (aka Impedance Imaging!) and geophysical (and process monitoring) ERT both use the same mathods as mathematically they are identical. In geophysics typically Loka's regularised Gauss-Newton method is commonly used, whereas in in medical and industrial we use different implementations of the same family of methods (see eg [1]). Just to make it clear EIT is also called tomography, but the critcism of them nams eis for the fact that you have to reconstruct a three dimensional image then take a slice of it, so that is not really tomographic. However in medical EIT the name was agreed by a vote at the first international conference on EIT in Sheffield in 1984. I was there and the vote was not unanimous. At least it was better than calling it Applied Potential Tomography in my opinion. As for your comment above, I am not sure what the difference is between 'method' and 'technique'.

That interesting about the vote on the terminology. I was aware that the applied math and physics between medical and geophysical applications are similar, so I'm not too far off. In geophysics, there are similar things as you described, acquiring and inverting a 3D dataset, where slices are extracted for interpretation. As far as Loke's work goes, he appears to avoid the term "tomography" (although he had originally named his software company "Geotomo Software"), and his web page intentionally uses "imaging" where appropriate (and same with most of his literature that I'm familiar with).+mwtoews 09:51, 19 February 2007 (UTC)

The terminology inconsistency does cause problems for practitioers. For the avoidance of doubt I recommend we adopt the US meaning for ERT and ERI for what is popularly termed 2D resistivity imaging in Europe and Africa.
ERT = Electrical Resistivity Tomography
Acquisition of resistivity measurements involving 4-electrodes per reading, between multiple strings of electrodes. Treatment of the data usually by tomographic reconstruction techniques.
ERI = Electrical Resistivity Imaging
Acquisition of resistivity measurements involving 4-electroders per reading, from a single multielectrode system. Inversion of data typically with finite element solutions.
ASEriksen (talk) 16:17, 20 February 2010 (UTC)

Note my name tag has slipped off some of the text above. The terminology is a mess but Wikipedia is not the pace to change it. I organized a meeting called "100 years of electrical imaging" at the Paris School of Mines. http://100electrical.geosciences.mines-paristech.fr/ .. the reason I used imaging was to include resistivity mapping as originally developed by Schlumberger before we had computers for inversion, as well as my view as above that it is not really tomographic. To me electrical imaging is the broadest inclusive term (including eg cross bore hole EM). It is unfortunate but true that the technique is mainly called Electrical Resistivity Tomography, especially by the contractors that do it. I do see a few people marketing it as (electrical) resistivity imaging on the internet, maybe to be distinctive, but I don't think it is a North America/Europe split as certainly plenty of US and Canadian contractors call it ERT (I hesitate to say most, such an exercise in thorough checking would certainly be Original Research WP:OR).Billlion (talk) 18:18, 29 December 2016 (UTC)