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105 results on '"Bakker, Wim"'

2. Hyperspectral Python: HypPy.

Author

Bakker, Wim, van Ruitenbeek, Frank, van der Werff, Harald, Hecker, Christoph, Dijkstra, Arjan, and van der Meer, Freek

Subjects
*IMAGE processing software, *FREEWARE (Computer software), *LIBRARY technical services, *PYTHONS, *MINERAL processing
Abstract

This paper describes the design, implementation, and usage of a Python package called Hyperspectral Python (HypPy). Proprietary software for processing hyperspectral images is expensive, and tools developed using these packages cannot be freely distributed. The idea of HypPy is to be able to process hyperspectral images using free and open-source software. HypPy was developed using Python and relies on the array-processing capabilities of packages like NumPy and SciPy. HypPy was designed with practical imaging spectrometry in mind and has implemented a number of novel ideas. To name a few of these ideas, HypPy has BandMath and SpectralMath tools for processing images and spectra using Python statements, can process spectral libraries as if they were images, and can address bands by wavelength rather than band number. We expect HypPy to be beneficial for research, education, and projects using hyperspectral data because it is flexible and versatile. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Infrared Hyperspectral Mineral Mapping–A New Approach for Sedimentary Core

Author

van Eijndthoven, Wijnand, Voskamp, Arne, van Ruitenbeek, F.J.A., Bakker, Wim Harry, Hecker, Christoph, Department of Applied Earth Sciences, UT-I-ITC-4DEarth, Faculty of Geo-Information Science and Earth Observation, and Digital Society Institute

Abstract

Conventional approach to hyperspectral imaging is to fit ‘pure spectra’ of minerals from a library to the measured image. This works well with minerals larger than the resolution of the hyperspectral camera . However in fine grained rocks, like most sediments, multiple minerals may be present within the imaging resolution. Interpretations might fit the wrong mineral spectrum to the mixed response giving ‘geologic unlogic’ results. While fitting a library the main criterium is, not fully taking into account the wavelength position and depth of the diagnostic mineral absorption features. The depth of the feature is an unconstraint indicator for the mineral concentration. To increase the accuracy of interpreting mineralogy in fine grained rocks and their concentration, the University of Twente (NL) and Deep Atlas B.V. co-developed an alternative approach to analyse hyperspectral images in the shortwave infrared domain. Dissecting the spectra per pixel into several wavelength maps allows individual assessment of chemical bonds within the (clay) mineral structure. Each wavelength map identifies the wavelength position of the first, second, and third absorption feature as well as the spectral depth of that feature. Using decision trees the wavelength maps and feature characteristics within, are used to identify the mineral present within each pixel. The depth of the absorption features is a semi-quantitative measure for the mineral content. Results from a detailed CHEMSCAN and SEM study were used to quantitatively calibrate the total clay content (the sum of white mica and clay minerals). In the development of this method the cut-offs from 26 QEMSCAN and SEM samples (provided by Wintershall Noordzee B.V.) were imaged. Comparing the QEMSCAN and SEM results to the imaging results their relationship could be defined in a regression formula. This regression model showed that the total clay content confidently can be modelled from the depth of clay features near 1400 and 2200 nm. Comparing absorption positions from wavelength maps to literature and each other, several (clay) spectral features (like Illite crystallinity, Fe content, clay content, and white mica composition) can be visualized in classified maps. The complete analysis results in a mineral map identifying the mineral species and characteristics per pixel. Individual mineral species concentrations and relations per depth interval can be derived from the analysis and exported for direct use in subsurface modelling studies. Concluding, Deep Atlas and the University Twente developed an accurate short-wavelength infrared hyperspectral mineral imaging method alternative to the conventional spectral fitting approach. The wavelength mapping method provides a useful, non-destructive way to identify and map white mica-, clay-, and carbonate minerals for sedimentary rock samples.

Published
2022

27. Cystic fibrosis: MR imaging of the pancreas

Author

Tjon A Tham, Richenel T.O., Heyerman, Harry G.M., Falke, Theo H.M., Zwinderman, Aeilko H., Bloem, Johannes L., Bakker, Wim, and Lamers, Cornelis B.H.W.

Subjects
Cystic fibrosis -- Complications, Magnetic resonance imaging -- Usage, Diagnostic imaging -- Usage, Examinations -- Validity, Pancreatic diseases, Pancreas -- Imaging, Health
Abstract

Cystic fibrosis (CF) is an inherited disease that affects the exocrine glands (which secrete enzymes and other substances through ducts). The pancreas may be severely compromised. Common complications of CF include respiratory infections and difficulty digesting food. Ultrasound (US; the use of high-frequency sound waves) and computed tomography (CT; computer generated images obtained through the use of X-ray) are two imaging techniques that have been used to examine the pancreas of CF patients. It has been reported that US is not sensitive enough to detect pancreatic abnormalities and CT, although highly sensitive, exposes young patients to radiation. The use of magnetic resonance (MR) imaging, which does not involve radiation exposure, was assessed as a means of detecting pancreatic abnormalities in patients with CF. Seventeen adult CF patients, 14 with abnormal pancreatic function and 3 with normal function, were examined with MR; 8 of the 14 were also examined by CT. The 14 patients who had known pancreatic problems showed abnormalities on both MR and CT scans. In the three patients with normal pancreatic functioning, MR findings were normal in two. In the 15 patients showing pancreatic abnormalities, three patterns were found. In nine patients, the pancreas appeared enlarged and normal tissue was completely replaced by fatty tissue. In five patients, the pancreas appeared atrophied (decreased or shrunken in size), with some normal tissue replaced by fatty tissue. In one case, the pancreas was atrophied, but no fat tissue replacement was seen. These results indicate that MR is as sensitive as CT in imaging the pancreas and revealing pancreatic abnormalities associated with CF. (Consumer Summary produced by Reliance Medical Information, Inc.)

Published
1991

30. Sensors

Author

Bakker, Wim, Bakx, Wan, Bijker, Wietske, Grabmaier, Karl, Janssen, Lucas, Horn, John, Huurneman, Gerrit, van der Meer, Freek, Pohl, Christine, Tempfli, Klaus, Tolpekin, Valentyn, Woldai, Tsehaie, Tolpekin, V.A., Stein, A., Department of Earth Systems Analysis, Faculty of Geo-Information Science and Earth Observation, Department of Earth Observation Science, UT-I-ITC-ACQUAL, and UT-I-ITC-4DEarth

Published
2012

35. A satellite view of the Hungarian sludge spill

Author

van der Werff, H.M.A., van der Meer, F.D., van Ruitenbeek, F.J.A., Bakker, Wim, Hecker, C.A., Department of Earth Systems Analysis, Faculty of Geo-Information Science and Earth Observation, and UT-I-ITC-4DEarth

Published
2011

37. Developing a distance education programming skills course fo geo - information sciences and earth observation students + powerpoint

Author

Ivanova, Ivana, Huisman, O., de By, R.A., Rutzinger, M., Bakker, Wim, Feringa, W.F., Retsios, V., Department of Geo-information Processing, UT-I-ITC-STAMP, Faculty of Geo-Information Science and Earth Observation, Department of Earth Observation Science, UT-I-ITC-4DEarth, Department of Earth Systems Analysis, and Department of Water Resources

Published
2010

50. 'Ephraem the Syrian's' Θpñvoς tñ&sigmaf Θεorókov: What? When? Where? Why?

Author

Bakker, Wim F.

Subjects
GOOD Friday, HOLY Week, GREEK manuscripts, LAMENTS, MOURNING customs, CHRISTIAN mourning customs
Abstract

The Threnos seu lamentatio sanctissimae Dei genitricis, quae dicitur in sancta et magna Parasceve, since long attributed to Ephraem the Syrian, appears to be a direct translation of the anonymous Θρ[This symbol cannot be presented in UNICODE format]νoς τ [This symbol cannot be presented in UNICODE format]ς [This symbol cannot be presented in UNICODE format]πϵραγíας ΘϵoτóκOυ ϵ [This symbol cannot be presented in UNICODE format]ς τ [This symbol cannot be presented in UNICODE format]ν στα [This symbol cannot be presented in UNICODE format]ρøωσıν τo[This symbol cannot be presented in UNICODE format] δϵσπóτoυ Χρıστo[This symbol cannot be presented in UNICODE format], published by Manousakas, and thus cannot be Ephraem's work. The Greek original, based upon troparia in the versus politicus of the fourteenth century, the Akolouthia of Good Friday and the second version of the Acta Pilati, must have been composed around the year 1400. There are strong indications that this text, a sort of amplified stavrotheotokion, has been sung for some time on Good Friday, outside the official service. [ABSTRACT FROM AUTHOR]

Published
2005
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