# % depth tolerance in Euler 3D

edited March 2018 in Geosoft
what is max. % depth tolerance,dz, dxy in Euler 3D and what is the relation between max. % depth tolerance,dz?

• what is max. % depth tolerance,dz, dxy in Euler 3D and what is the relation between max. % depth tolerance,dz?
• mod
Hi @PankajKumarDas I thought your question deserved it's own discussion!
Community Manager

• Hello @PankajKumarDas

dZ represents the depth uncertainty in Z as a percentage of the solution depth. For example, if a given solution depth is 500m and dZ = 10, then the depth uncertainty for that solution is 50m.

dXY represents the location uncertainty in XY as a percentage of the solution depth and works in the same way as I have described for dZ above

We observe a general relationship between structural index (SI) and dZ and dXY, in that using a lower structural index will generally produce solutions that have higher uncertainties. This general relationship is described in the table below.

Darren Andrews
Technical Team Manager

• Thank you Sir
• I am a beginner of Geosoft.
What is max. % of depth tolerance?
• Hello @DarrenAndrews! Very good explanations about uncertainties in respect of structural index, by the way... where did you find the table you have shown above? Very interesting!
• Hello @PankajKumarDas , there is no maximum % depth tolerance as such, merely an uncertainty that changes based on the structural index, as described above.
Darren Andrews
Technical Team Manager

• edited June 2018
Hello @DarbyLima. The table is taken from our documentation and is based on observations while developing and testing Euler Deconvolution. For further context, I'd urge you to take a look at our learning path lesson on Euler Deconvolution
(https://my.geosoft.com/elearning/lessons/#/reading/846) under the section "Understanding Solution Uncertainty".

This relationship between SI and solution uncertainty has been described by others, including Reid et al (1996, reference below) who state the following regarding solution uncertainty:

"Where a (Euler deconvolution) window does not include any significant gradients or where it includes gradients arising from several sources, the solution has a high uncertainty. Noisy or poorly gridded data sets also affect the solution statistics by degrading the fit. In addition, we observe that the lower the structural index employed, the worse the precision, even when the (structural) index used is the appropriate one. This is the case for both model and real data."

Reference: Reid, A.B., Allsop, J. M., Granser, H., Millett, A. J., Somerton, I. W., 1990, Magnetic interpretation in three dimensions using Euler Deconvolution, Geophysics. Vol.55, pp.80-91
Darren Andrews
Technical Team Manager

• @DarrenAndrews , Thank you very much for the attention and explanations. Very useful!
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