Digital Structural Mapping of the Moine Thrust foreland at Loch Assynt, Scotland: Introduction of a 3D visualization system into a Level 2 field trip
Contact details
Dr Ken McCaffrey
Department of Geological Sciences
University of Durham,
Durham, DH1 3LE
Tel: 0191 334 2333
Fax: 0191 334 2301
Email: k.j.w.mccaffrey@durham.ac.uk
Classification Category
- Develops student appreciation of research and brings data/findings from
staff research into the curriculum
Context
- Course/unit/module title: Geology/Geological Sciences/Fieldwork
- Course title: Fieldwork
- Level 2
What does the teacher do?
Digital structural mapping (DSM) methods involve the acquisition of field data on hand-held computers operating Geographical Information Systems (GIS) software. By connecting to a GPS receiver, geospatial control on observations is automatically provided. With technology advancing rapidly, driven by applications in the engineering, construction and environmental monitoring industries, digital field mapping systems are now becoming affordable and can attain equivalent or better positional performance than is routinely achieved by traditional methods (compass clinometer, etc). For the field geologist there are a number of obvious advantages. Powerful multi-attribute mapping and high-resolution spatial analysis can be carried out during fieldwork. The ability to view and analyze data collected at each stage allows an iterative approach to be taken to field problem solving. Data may be directly imported to 3-D visualization, analysis and 4-D modeling packages, which can provide further constraints on the viability of the interpretation. Digital formats ensure that the 'field to report' process is more streamlined.
We have recognised that during mapping training, some students have less developed 3-D spatial awareness than others. It is essential that geologists can build up a 3-D mental picture of their surroundings in order to solve geometrical problems commonly confronted in the field. This ability is very difficult to teach in the laboratory and it consistently remains an aspect of fieldcraft that students either 'get' immediately or struggle with for long periods of time. In order to aid those students who have difficulty with their 3-D visualization, we have developed a series of computer models which allow the students to view the sites they where at during the preceding day, to see a virtual 3-D representation of the geology and its larger-scale context. They can then use this visualization with to reinforce and enhance their own observations, interpretations and mental picture of the geology.
To build the 3-D model, a base map was constructed from Ordnance survey digital data in ArcGIS™. It comprises a digital terrain model that was overlaid by aerial photographs, remote-sensed images and other cartographic data. This is then projected into 3-D using ArcScene™ software. The lithological boundaries that the students map in the field had previously been accurately surveyed (resolution <30cm) using a Differential Global Positioning System receiver attached to a handheld computer. These boundaries were used to create a geological map overlaid onto the digital base map that and viewed in 3D. The 3-D model was progressively revealed to students in conjunction with their own mapping of the area, on a laptop available during their evenings work periods. They were able to rotate the model; fly around their virtual mapping area and zoom in to places they have been, allowing them to revisit their observations and interpretations. The students were directed by staff to think about the geometry of the major structures and how this results in the observed rock outcrop patterns. The students could also see how their small piece of work fits into the larger picture of the geology of NW Scotland.
Hot tips and things to look out for
Make sure you have completely constructed the 3-D model before showing it
to the students. Make sure it loads on the lap-top you will be using. They
are not impressed by having to wait while you reload the model for the third
time in order to get it to work.
Does it work?
Numerical data from student questionnaires
Course: Yr 2 Assynt
Year Range: 2002
Mean Number of students: 48
Average Response: 91%
Q.1*: 4.5
Q5**: 4.1
Q.7***: 4.9
*Q.1 Overall, did you find it helpful to be able to view computer-based models
in the evenings (1 not helpful 5 - very helpful)
**Q.5 - Do you think you understand the 3-D structure of the area better as
a result of viewing the models (1 no better 5 - much better)
*** Q7 - Do you think it is worthwhile us developing these models further
for future field-classes (1 - not worthwhile 5 - very worthwhile)
Other staff on the fieldtrip commented that the computer models provided an
excellent tool for reinforcing the main points for each day and he students
clearly found the models of help in developing their 3-D visualization abilities
and they gave a resoundingly encouragement to their future development.
What problems/issues have arisen?
The models were only available for students to look at on an individual basis after the days work as we but we had only one lap-top capable of running the models thus limiting their accessibility. In future we plan to have at least two computers capable of demonstrating the models, and also to provide the data files for the students to access in their own time back in Durham. We also plan to link the models to ongoing coursework in at least tow modules after the fieldtrip
Details of support material/course work/assessment methods
In its first trial year we did not issue instruction sheets to students,
however, in it subsequent years supporting help-sheets and coursework will
be developed. Contact Ken McCaffrey for further details.
Relevant references
Information provided by Ken McCaffrey. Bob Holdsworth has delivered the Assynt field course since 1997 to students studying degrees delivered by the School of Earth Sciences, University of Durham.Ken McCaffrey has been involved since 2000 and has developed the 3D computer models For further information visit the following webpage: