PROPOSAL
3-D Digital Geology: Acquisition,
Visualization and Analysis (CyberMapping)
2001 University of Texas at Dallas Consortium
Introduction
You are invited to participate in the UT-Dallas "Consortium
for 3-D Geology: Acquisition, Visualization and Analysis" for the year
2001. 3D photorealistic models of geologic outcrops are acquired on the ground
with reflectorless laser rangefinders, GPS and oblique close-in photography at
centimeter to decimeter accuracy. The result is a 3-D virtual model that can be
used for 3D visualization and/or analysis. The model eliminates perspective
problems existing in 2D photomosaics and its geometry can be quantitatively
analyzed by taking the digital outcrop back to the office where it can be
analyzed at the accuracy and resolution it was acquired. It is many times faster
than overlapping stereo photography, drastically decreasing the time and cost of
the data acquisition and the final post-processing and participant personnel can
be easily familiarized with and trained in use of the necessary equipment and
software. . For example there are thousands of detailed, interpreted
photomosaics that exist as part of outcrop mapping such as in reservoir
characterizations. These can now be expeditiously, economically and accurately
(centimeter to decimeter) converted into 3D digital photorealistic models, which
then allow the extraction of quantitative 3D accurate geometric information.
There are other natural or even man made (buildings etc.) features of interest
that can be captured and visualized photorealistically in 3D to be used for
teaching and display. Virtual 3-D field trips are a reality.
Our
CyberMapping (patent pending) method is used for data acquisition and accurately
draping photography (even a single photo) onto centimeter to decimeter digital
terrain models generated by reflectorless laser mapping by the user. Acquisition
and processing software developed at UTD are unique in their functionality and
is the key to the success of the method. The consortium objectives are to
provide this approach to members of the consortium through access to our
software and training on its use in the field and in the lab. In addition
results of field data acquisition projects that have been carried out to
generate 3D models of a variety of case histories including geometric analysis
will be provided. Each year during the consortium new areas will be captured and
studied as 3D photorealistic models. Participants have input as to the areas to
be captured.
The Cybermapping Laboratory of the Dept. of Geosciences/Center for Lithospheric Studies have been doing cutting edge digital acquisition of geology for several years as discussed in several papers and Geological Society of America manuals (Xu, Aiken and Nielsen, 1999; Nielsen, Aiken and Xu, 1999; 2000; Xu and others, 2000) and a patent application (Aiken and Xu, 2000). UTD has defined the method and equipment to efficiently and accurately acquire such data. This group was the first to import and display in 3D virtual visualization systems (at three petroleum industry sites, ARCO Exploration and Technology's and Norsk Hydro's "caves" and ExxonMobil's curved screen).
Objectives
This proposal is for the first year of an annual consortium to
support the development and improvement of the methodology and technology for
the capture of 3D terrain and geology, their photorealistic visualization, and
quantitative analysis of their geometry. Participants will be provided with
software licenses, methodology, training, in-the-field joint work on the
consortium projects, models of already mapped and newly mapped outcrops as well
as information on new developments in equipment, software and procedures
It will be shown how all this can be applied to almost any area of terrain or
geologic interest (if you can see it and get within at least 500m of it you can
map it, and with some technology, to 1000m). These methods will be applied to
specific locations, going into the field and converting interpreted photomosaics
for example to accurate (centimeter to decimeter), 3D quantitative models
consisting of laser mapped digital terrain and features (contacts, faults etc.),
integrated with a photorealistic surface from oblique photography draped onto
the terrain. The level of funding, and the principal investigators and the
participants will determine the choice of those locations and their number. For
example UTD has been building a 3-D surface/subsurface model of deltaic channels
in the Ferron sandstone at Corbula, Utah with ground penetrating radar,
coreholes, strat sections and laser mapping. The photorealistic surfaces will be
completed and integrated this year. A nearby GPR/geologic study of the Ferron at
Coyote Creek will be converted into a 3-D photorealistic/surface/subsurface
model also.
Participants can work in the field with UTD to train in the use of the
software/hardware and have licenses of UTD's unique processing and data
acquisition software. In addition, results have been exported into a variety of
3D virtual environment systems successfully and so information for such format
conversion and data import/export will be provided. It will be shown how our
photorealistic models can allow extraordinarily detailed quantitative
interpretations to be made in the office. Analyzing such detailed, accurate yet
clustered data sets however can be difficult and our approach and methods in
that area will also be provided.
Planned equipment developments include underwater rangefinding, mounting the
system on airborne platforms and robotic rangefinding less costly than now
available, as well as improving the general accuracy characteristics of the
available rangefinders. Planned software developments include modifications to
allow more in-the-field analyses and photo registration, the use of palmtop
computers and conversion of the software to Java. Our software integrates with
range of hardware but that can be extended to other GPS, laser rangefinding and
computing equipment when necessary.
Separate arrangements will be made for acquisition and model building in other locations as well as system support and training depending on the interest of participants. If members of the consortium have locations of interest to be mapped it could be done for expenses, with the digital data sets held confidential for a period of time. Other types of projects could be also arranged outside the consortium.
Schedule/Costs
The annual fee per participant is $25,000.
The consortium term will be from January to December with a meeting held at UTD
once a year, in January to determine work to be done during the following year
and to present results from the previous year. Visits by participants during the
year for demonstrations, instruction etc. will be scheduled. A meeting will be
at the annual AAPG meeting to display results and progress (and in 2001 to
discuss planning). Training will be carried out using UTD's latest software,
procedures and equipment for acquisition, processing, and analysis for those
interested at UTD, and in the field on actual projects. Results will be
transferred digitally to participants as they are completed through a web site.
The earlier the participants join, the more impact they have on the areas to be
studied. Finished projects will be provided, including ones of the Austin chalk,
the Ferron sandstone and such. Information on joining the consortium will be
provided by contacting Dr. Aiken (see below).
Dr. Carlos L. Aiken
University of Texas at Dallas
Center for Lithospheric Studies
P. O. Box 830688
2601 N. Floyd Rd.
Richardson, Texas 75083-0683
(972) 883-2450 / fax: (972) 883-2829
aiken@utdallas.edu
Background
A system has been developed that consists of hardware (laser
rangefinders, GPS, ruggedized field computers, digital cameras), software
including UTD's CyberMapping and CyberPhoto, and methodology to map outcrops
digitally at the accuracy of centimeter to decimeter with GPS, lasers and
cameras. The result is a digital model that is accurate (3 dimensionally
geometrically and geographically), with 3D surfaces fit to bedding, fault traces
and other contacts and terrain. This has been applied to cases in Utah, Texas,
Wyoming, Arkansas, Colorado, Oklahoma, Nevada and Egypt. In some of these cases
conventional methods of mapping geology have been integrated with the data
produced digitally such as from compass measurements, stratigraphic sections and
wells. Geophysical data such as ground penetrating radar has also been
integrated. In some cases photorealistic surfaces have been draped onto the
digital terrain to create the ultimate virtual 3D model. Such models have been
imported into and utilized in several virtual immersive visualization systems.
Additional 3D geologic information can be extracted quantitatively by digitizing
directly from the photorealistic model. UTD has a unique experience in such
digital mapping and visualization and analysis in numerous locations and
geologic environments.
Models will consist of digital terrain, feature mapping (including specific
attributes such as faults, bedding, and other contacts), and photomosaics draped
onto the topography. All data will be globally positioned and geometrically
accurate at centimeters to decimeters depending on the technology applied and
the characteristics of the locations. Features such as faults and bedding will
be fit to 3D surfaces. Input from participants will be encouraged. Specific
model formats will be customized in various formats as necessary for
visualization needs of the participants.
Several completed studies including mapping of delta plain channels in the
Cretaceous Ferron sandstone in Utah, which also have 3D GPR data, as well as our
initial photorealistic model of the faulted "Bulk Mail Station" Austin
Chalk outcrop in Dallas, Texas will be provided. The latter is attached in
Figure 1 to this proposal. It shows 100 meters of a 20-meter high exposure of
terrain and its ultimate photorealistic model and the resultant 3D surface
geometry analysis of fault and bedding surfaces, all at centimeter accuracy.
Also in attached Figure 2 is the partial result of work being done with Veritas
Exploration Services on the deep water Jackfork formation at North Little Rock,
Arkansas with accuracy of 2-5 centimeters. The 1000 meters of laser mapped
quarry are shown as well as a portion of it shown as the surface laser mapping,
its terrain mesh and then a portion as a 3D photorealistic model in two
perspective angles. Figures 3 and 4 display the results of the Dallas outcrop in
Norsk Hydro's 3-D virtual visualization "CAVE".
Consortium members are encouraged to also participate in field acquisition and
later model building activities and visualization methods and analyses. These
results are more accurate than any other mapping approach, and are also digital
and photorealistic. 3D volumes can be used to model synthetic seismograms, to
provide data on reservoir characteristics and to analyze structural geometries.
The virtual outcrops can also be effectively used for teaching and
demonstrations and are ideally suited for incorporation virtual reality
facilities and immersive visualization environments.
Other examples of results can be see in several places in our web site http://www.utdallas.edu/~xuxue/cyberlab.html) or.edu/dept/geoscience with links through Aiken, Bhattacharya, McMechan, the Center for Lithospheric Studies and other students and professors using our system. You can also download/play an mpeg animation of the analyzed "Post Office" Austin chalk 3D photorealistic model which rotates, translates, zooms in and out etc.
Facilities/Equipment
UTD is equipped with instrumentation relevant to digital geology exceeding any other organization doing digital geologic mapping, including 2 Leica RTK GPS 530 systems (4 dual frequency receivers in all), 2 Trimble 4000SSE dual frequency receivers, a Landstar RACAL Real Time DGPS system, two continuously operating (a key capability in our system) Laser Atlanta Advantage CI refelectorless laser rangefinders with Bogen tripods with improved horizontal and vertical angle encoders, a TOPCON GPT-1002 reflectorless total station (which when operated with our software operates in a continuous mode, and two ruggedized pen-based Pentium field computers to operate our field acquisition software CyberMapping. Our patented software has the unique capability to visualize the laser mapping in 2D mapping mode as well as in 3D perspective views, and other functionalities, such as effectively determining the status of the mapping, all in the field in real time. It also allows preliminary analyses such as real time strike and dip determination of laser mapped features and thickness, basically real time estimates of structure and stratigraphic thickness. UTD also has 5 seats for GOCAD 3D visualization software, full ERSI (Arcview, ArcInfo etc.) licenses and other useful software. If the participants have other equipment, which has the required capabilities, then their input formats can be modified to work with our software.
Project Leaders
The work will be under the direction of Dr. Carlos Aiken, with
software development under Dr. Xueming Xu, both originators and developers of
the approach. They have presented their methodology and results in two training
short courses at the Geological Society of America annual meetings (1999, 2000)
and to ExxonMobil Upstream Research Co. and Norsk Hydro ASA. They will be
working with several geoscientists at UTD including geophysicists George
McMechan and John Ferguson, sedimentologist Dr. Janok Bhattacharya and
structural geologists Drs. Kent Nielsen, Mohamed Abdelsalam and Russell Davies
as well as other scientists and graduate students.
Vita of Principal Investigators
Dr. Carlos L. Aiken
Full Professor of Geosciences
University of Texas at Dallas
Center for Lithospheric Studies
Department of Geosciences
P. O. Box 830688
2601 N. Floyd Rd.
Richardson, Texas 75083-0683
(972) 883-2450 / fax: (972) 883-2829
aiken@utdallas.edu
Dr. Carlos L. V. Aiken is a full professor of Geosciences at UTD, with specialties in geophysics, Geographic Information Systems, Global Positioning Systems, and digital acquisition, visualization and analysis of geologic outcrops. He has concentrated for the last 5 years in geologic data conversion first from paper products and then with GPS and lasers and has been using and teaching GPS applications to geosciences for 10 years. He started using laser rangefinders for terrain mapping for gravity terrain corrections, which is now the standard for inner terrain corrections in gravity surveys. He teaches courses in GPS, GIS and digital data acquisition.
Education
B.S., Geology, University of Washington, 1965
M.S. Geological Sciences, University of Washington, 1970
Ph.D. Geosciences, University of Arizona, 1976
Academic Experience
1989- Professor, Programs in Geosciences, UTD.
1981-1989 Associate Professor, Programs in Geosciences, UTD.
1978-1981 Assistant Professor, Programs in Geosciences, UTD.
1976-1978 Assistant Professor, Department of Geology, Texas Christian University
1975-1976 Instructor, Department of Geology, Texas Christian University
Other Relevant Professional Experience
2000
Instructor, seminar (5 days), Norsk Hydro ASA, Bergen, Norway,
Digital geologic acquisition, Visualization and analysis.
Co-Instructor, Seminar (1 day) ExxonMobil Upstream Research Co.,
Digital geologic acquisition visualization and analysis.
Co-instructor, (2 days) Geological Society of America Short Course, Digital
Mapping Methods: Accurate Digital Data Capture and Analysis for the Field
Geoscientist, Reno, NV
1999
Co-instructor, (2 days) Geological Society of America Short Course, Digital
Mapping Methods: Accurate Digital Data Capture and Analysis for the Field
Geoscientist, Denver, CO.
1997
Geophysical consultant, Hunt Oil
1997 GPS
consultant, Tarrant County 911 District
1993
Navtech Training Courses on differential GPS and high accuracy GPS.
1992-95 Consultant, U. S. Geological
Survey; GPS Processing of Kinematic GPS Surveys, National Mapping Division.
1992
Consultant, Kinematic GPS Surveys, Red River Valley, for U. S. Corps of
Engineers.
1991-1992 Member, Steering Committee on Surveying,
Deformation, Subsidence and Monitoring on Superconducting Super Collider for PB/MK
TEAM, SSC engineering contractors.
1991
Consultant, Nevada Bureau of Mines and Geology, GPS Processing of Las Vegas
Basin Subsidence Study.
1988 GPS
Training and Advanced Training Seminar, Trimble Navigation, Sunnyvale, CA.
1988
UNAVCO GPS Training Seminar, Scripps Institution of Oceanography, La Jolla, CA.
1982?1985 Faculty member Summer of Applied Geophysical Experience,
Institute of Geophysics and Planetary Physics, University of California
1976-94 Consultant, Los Alamos
National Laboratory
Relevant theses/dissertations
T. C. Stallings, M.S., 1994, Establishing a geophysical and geological GIS
database of Mexico and demonstrating GIS as a relational tool for
interpretation.
M. Balde, Ph.D., 1994, Vertical control by GPS satellite surveying techniques and high resolution geoid computation: Applications in high accuracy mapping and geophysical data acquisition.
Lyman, Gregory D., 1997, Terrain mapping by reflectorless laser rangefinding systems for inner zone terrain corrections
Xu, Xueming, 2000, PhD, 3D Virtual Geology; photorealistic
outcrops and their acquistion, visualization and analysis.
Dr. Xueming Xu
Research Associate
University of Texas at Dallas
Center for Lithospheric Studies
P.O. Box 830688
2601 N. Floyd Rd.
Richardson, TX 75083
xuxue@utdallas.edu
Education
B.S., Geology, Nanjing University, China, 1987.
M.S., Geology, Nanjing Institute of Geology and Paleontology, Chinese
Academy of Science, 1989
Ph.D, University of Texas at Dallas, 2000.
Dr. Xu is involved in real time digital geological and geophysical field data acquisition and its applications, Global Positioning System (GPS), digital photography and Geographic Information System (GIS) in geological /geophysical 3D modeling. He has converted paper geologic maps of Mexico, Peru, China, provinces of China, and parts of the US into GIS formats, been involved in numerous digital geologic projects, has been trained in computer visualization, and has written unique software that has made digital geologic data acquisition successful. His dissertation was the basis of the short course manuals and the basis to CyberMapping and digital geologic data capture.
Relevant Experience
2000-present, Center for Lithospheric Studies, University of Texas at Dallas,
research associate.
1995-2000: Department of Geosciences of University of Texas at Dallas, Research
Assistant and Teaching Assistant.
1992-1994: Visiting scientist at Center for Great Lake Studies at The University
of Michigan. Research on impact of global climate changes on ecology system.
1989-1992, Nanjing Institute of Geology and Paleontology, Chinese
Academy of Science, research scientist.
Patent
C. Aiken and X. Xu (co-inventors), 2000, Method and Apparatus for 3D Feature
Mapping
Copyrighted Software
CyberMapping, real time digital geologic data acquisition with GPS, lasers, and
cameras.
CyberPhoto, photo registration and draping.
Book (in preparation)
X. Xu, Carlos L. V. Aiken, and Kent C. Nielsen, 3D Virtual geology: Electronic
data capture and analysis for the field scientist.
Relevant papers by Aiken and Xu
Leick, A., C. Aiken, and J. Kor, 1991, Initial GPS and leveling references for
the SSC, in Proceedings of 1991 ACSM-ASPRS Fall Convention, Atlanta, GA, October
28 - November 1.
Ferguson, J., D. Ziegler, C. L. V. Aiken and A. Cogbill, 1991, Geodetic experiment on Nevada Test Site events using the Global Positioning System, in Geophysical Investigations at Pahute Mesa, Nevada (J. Ferguson), Defense Advanced Research
Balde, M., C. L. V. Aiken, D. G. Ziegler and J. Hare, 1992, Stop and go kinematic GPS for position control in a large scale gravity survey in North Dakota, in Proceedings of the 6th International Geodetic Symposium on Satellite Positioning, Columbus, OH, p. 769-777.
Ziegler, D., R. L. Hunt and C. L. V. Aiken, 1992, Rapid GPS Positioning of a gravity survey in the South Georgia Basin, Georgia, using the Two Occupation Rapid Static Ambiguity Function technique, in Proceedings of the 6th International Geodetic Symposium on Satellite Positioning, Columbus, OH, p. 759-768
Leick, A., M. Carr and C. L. V. Aiken, 1992, Superconducting Super Collider GPS Networks, in Proceedings of the 6th International Geodetic Symposium on Satellite Positioning, Columbus, OH, p. 789-800.
Hothem, L., and C. L. V. Aiken, 1992, Comparison of DGPS and Double Difference Carrier Phase results from a land-based kinematic survey, Proceedings of the Institute of Navigation 48th Annual Meeting, Washington, DC.
Hothem, L. and C. L. V. Aiken, 1992, Assessment of DGPS-derived aircraft trajectories by comparison with continuous kinematic GPS positioning in Proceedings of the Institute of Navigation 48th Annual Meeting, Washington, DC.
Aiken, CLV, 1994, South American Gravity Data CD-ROM, in Gravity (1994 - CD-ROM, Hittelman, R., Deter, D., Buhmann, R., and Racey, S., 153,859 gravity principle facts and report).
Brady, J., D. S. Wolcott, P.H. Daggett, J. F. Ferguson, J. L. Hare, C. L.V. Aiken, J.E. Seibert and G. Mader, 1995, Water Movement Surveillance with High Resolution Surface Gravity and GPS; A Model Study with Field Results, Proceedings of Society of Petroleum Engineers Meeting, p.381-394.
Aiken, CLV, M. Balde, X. Xu, MG Abdelsalam, MF de la Fuente and M. Mena, 1997, Integrated studies of Mexico with gravity, magnetic and GIS database, Leading Edge, Society of Exploration Geophysicists, p. 1779-1785, Dec.
Aiken, CLV, M. Balde, JF Ferguson, GD Lyman, X. Xu and AH Cogbill, 1998, Recent developments in digital gravity data acquisition on land, Leading Edge, Society of Exploration Geophysicists p. 93-97, Jan.
Aiken, CLV, GD Lyman, M. Balde, and X. Xu., 1997, An Integrated Digital Gravity/GPS/GIS/Reflectorless Laser System for High Resolution Gravity Surveys, Proceedings from the High Resolution Geophysics Workshop, University of Arizona, Tucson, Az, CD-ROM.
Balde, M., J. Fishman, C.L.V. Aiken, M. Abdelsalam, M. F. de la Fuente, 1999, A GPS Supported Gravity Survey in the Amazon of Ecuador, GPS Solutions, and V: 3, p. 3-18.
Hare, J.F. Ferguson, C.L.V, Aiken and J. L. Brady, 1999, A 4-D microgravity method for water flood surveillance: A model study for the Prudhoe Bay Reservoir, Alaska, Geophysics, Jan., p. 78-88.
Xu, X., Aiken, C., Neilsen, K. S., 1999, "Real Time and the Virtual Outcrop Improve Geological Field. Mapping", Transactions of The American Geophysical Union, EOS, v. 80, p. 322-324.
Hare, J., Ferguson, J. F., Aiken, C. L. V. and Brady, J. L., 1999, "A 4-D microgravity Method for Waterflood Surveillance: A model study of the Prudhoe Bay Reservoir, Alaska," Geophysics. Res., p. 78-88.
Balde, M., Fishman, J., Aiken, C. L. V., Abdelsalam, M. G. and de la Fuente, M. F., 1999, "A GPS Supported Gravity Survey in the Amazon of Ecuador," GPS Solutions, v. 3, p. 3-18.
Xu, X., Aiken, C., Nielsen, K. S., 1999, "Real Time and the Virtual Outcrop Improve Geological Field Mapping", Transactions of The American Geophysical Union, EOS, v. 80, p. 322-324.
Corbeanu, H., Brikowski, T. and Aiken, C, 2000, "Landslide Monitoring in Romania," GPS World, March, p38-42.
Hare, J., Ferguson, J., Aiken, C. L. V. and Oldow, J., 2000, submitted and in review, Journal of Geophysical Research, "Quantitative Characterization and Elevation Estimation of Lake Lahonton Shoreline Terraces from High Resolution Digital Elevation Models."
Xu, X., Bhattacharya, J., Davies, R. K., and Aiken, C. L. V., 2000, in press, "Digital Geologic Mapping of the Ferron Sandstone, Muddy Creek, Utah with GPS and lasers" GPS Solutions, John Wiley.
Xu, X., Aiken, C., Bhattacharya, J. P., Corbeanu, R. M., Nielsen, K. C., McMechan, G. A. and Abdelsalam, M. G. 2000, "Creating Virtual 3D Outcrop," Leading Edge, Soc. of Exploration Geophysicists, February, p.197-202.
Oldow, J., Aiken, C., Ferguson, Hare, J. and Hardyman, R., 2001 in press, Active displacement transfer and differential motion between tectonic blocks within the central Walker Lane, western Nevada, Geology.
Nielsen, K. C., Aiken, C. L. V., and Xu, X., 1999, "Digital Mapping Methods: Accurate Digital Data Capture and Analysis for the Field Geoscientist," GSA Continuing Educational Manual, Geological Society of America, 119 p.
Nielsen, K. C., Aiken, C. L. V., and Xu, X., 2000, "Digital Mapping Methods: Accurate Digital Data Capture and Analysis for the Field Geoscientist," GSA Continuing Educational Manual, Geological Society of America, 119 p.
47 relevant abstracts since 1990 involving GPS, GIS, laser mapping, and digital geology.
Figure 1. The photorealistic outcrop of the Bulk Mail Station, Texas. (The outcrop is about 100 meters long, and face about 20 meters high. All figures by GOCAD).
Fig.
1-A. The interpreted layers and faults determined by surface fitting of the
digitally mapped geology. The features in the center are extracted from the
photorealistic model tied to features directly laser mapped (looking down from
the north).
Fig. 1-B. The model in A is merged with the digital terrain model.
Fig.
1-C. Five photos were taken at different times of the day (shown as photos
are, from the left, the first and last three, taken on the same day but over
several hours---this was a test) and different times of the year (the other two
photos, the second and third from the left,) draped onto the terrain model. Note
the parking lot surface at the bottom the slope.
Fig.
1-D. Features in Fig.
1-C rotated to a different perspective angle. Note the fence and poles are
also draped onto the terrain (because they were not separately registered). For
cosmetic purposes of course all the photos should be taken as close in time as
possible to preserve the same lighting conditions. Note that the model consists
of five separate photos individually registered and individually draped onto the
terrain.
Figure
2. Photorealistic outcrop of Big Rock Quarry (deepwater Jackfork
Fig.
2-A. Perspective plot (looking down from the south) of the laser mapping by a
robotic laser rangefinding system (color coded by relative elevation). Total
outcrop face about 1000m, height of face, 60m.
Note the light poles and trees. Points accurate to approximately 5
centimeters.
Fig. 2-B. Portion of the southeast end of that seen in Fig. 2-A also color coded
Fig.
2-C. Three merged photos draped onto the terrain of Fig.
2-B creating a photorealistic 3D model.
Fig.
2-D. Different scale of Fig.
2-C showing the triangulated mesh created from the laser mapping rotated
to display the relief of the face of the quarry.
Fig.
2-E. Fig.
2-D with the photos draped onto the mesh for a 3D photorealistic model.
Figure 3.
Example of the Mail Station outcrop displayed in Norsk Hydro’s
3-D virtual visualization “CAVE” system in November, 2000.
Figure 4. Example of the Mail Station outcrop
displayed in Norsk Hydro’s
