Day: October 8, 2014

Program of the month: sfsigmoid

October 8, 2014 Programs No comments

sfsigmoid generates a 2-D synthetic reflectivity model, created by Jon Claerbout.

One of the first occurrences of this model is in SEP-73 sponsor report from 1992, where it appeared in several papers:

  • J. F. Claerbout, 1992, Introduction to Kirchhoff Migration Programs: SEP-73 report, 361-366, Stanford Exploration Project.
  • J. F. Claerbout, 1992, Filling Data Gaps Using a Local Plane-Wave Model: SEP-73 report, 401-408, Stanford Exploration Project.
  • J. F. Claerbout, 1992, Information from Smiles: Mono-Plane-Annihilator Weighted Regression: SEP-73 report, 409-420, Stanford Exploration Project.
  • J. F. Claerbout, 1992, Crossline Regridding by Inversion: SEP-73 report, 421-428, Stanford Exploration Project.

    The model was described as “a synthetic model that illustrates local variation in bedding. Notice dipping bedding, curved bedding, unconformity between them, and a fault in the curved bedding.” Later, the sigmoid model made an appearance in Claerbout’s book Basic Earth Imaging. The following example from bei/krch/sep73 illustrates the effect of aliasing on Kirchhoff modeling and migration:

The model has appeared in numerous other tests. The following example from tccs/flat/flat shows automatic flattening of the sigmoid model by predictive painting.

sfsigmoid has several parameters that control the model. The usual n1=, n2=, o1=, o2=, d1=, d2= parameters control the mesh size and sampling, taper= indicates whether to taper the sides of the model, large= controls the length of the synthetic reflectivity series. The program takes no input.

10 previous programs of the month:

High-performance computing and open-source software

October 8, 2014 Links No comments

A recent Report on High Performance Computing by the US Secretary of Energy Advisory Board contains a bizarre section on open source software, which states

There has been very little open source that has made its way into broad use within the HPC commercial community where great emphasis is placed on serviceability and security.

In his thoughtful blog post in response to this report, Will Schroeder, the CEO an co-founder of the legendary Kitware Inc. makes a number of strong points defending the role of open source in the past and future development of HPC. He concludes

The basic point here is that issues of scale require us to remove inefficiencies in researching, deploying, funding, and commercializing technology, and to find ways to leverage the talents of the broader community. Open source is a vital, strategic tool to do this as has been borne out by the many OS software systems now being used in HPC application… ItÂ’s easy to overlook open source as a vital tool to accomplish this important goal, but in a similar way that open source Linux has revolutionized commercial computing, open source HPC software will carry us forward to meet the demands of increasingly complex computing systems.

See also Will Schroeder’s presentation The New Scientific Publishers at SciPy-2013.