Newsletter - December 2009
GPR-SLICE users,
I would like to welcome the following organizations:
1. Bartlett Clark Consultancy, Oxfordshire, UK
2. Old City Core ltd., Croatia
3. GeoStudi, Livorno, Italy (www.geoastier.com)
4. Geophysics Unit, Orkney College, Scotland
5. Copernico, S.r.l., Montalcino, Siena, Italy
6. Archaeology Dept., University of Science and Technology, Trondheim, Norway
7. IDD, France
8. Roads and Traffic Authority, Parramatta, Australia
9. Geoforce Pty Ltd, Malaga, Australia (www.geoforce.com.au)
10. CSIRO-QCAT, Brisbane, Australia
11. KONSTAT BIRO d.o.o, Slovenia
12. CAI Archaeometry and Analysis, University Computense of Madrid, Spain
13. Laboratoire Central des Ponts et Chaussées, France
14. Heritage Preservation and Interpretation Inc., Steamburg, New York
15. Round Rock GeoSciences LLC, Round Rock, Texas (www.roundrockgeo.com)
16. Energy and Environment Research Laboratory, ITRI, Taiwan
17. VISTA Centre, Birmingham Archaeology, University of Birmingham, UK
(www.vista.bham.ac.uk)
18. Hawaii Geophysical Services, LLC (www.hawaiigeophysicalservices.com)
19. Environmental and Historic Preservation, FEMA, Mississippi
20. Geophysical Researchers Consulting, Bogota, Columbia
GPR-SLICE V6.0 www.GPR-SURVEY.com
Updates
The new features added to GPR-SLICE v6.0:
1) Overlay Analysis “O” button for 3D displays
2) Assisted Auto-hyperbola detection for Bridgedeck licenses
3) Automatic bandpass filter design
4) US Radar equipment manufacturer header imports
1) Overlay Analysis in 3D
Overlay analysis provided in GPR-SLICE allows the user to overlay the
relative-strongest-reflectors onto a single time slice map. This functionality
has been available in the 2D Time Slice menu since the inception of the GPRSLICE for DOS. The 2D time slice menu was the only location one could
apply this very useful imaging technique.
The overlay analysis is now available in the 3D Open GL Volume menu.
The new “O” button will add the relative-strongest-reflectors onto
consecutive time slice levels. To start the overlay below the ground surface
levels or any desired level, one can click the “Z” button, step or bounce to
the desired level, then click the “O” button to start overlaying the reflection.
An example of the “O” button to make 3D overlay displays is shown in
Figure 1. This dataset is the same dataset available for all users in the
Advanced Users Workshop folders on the ftp site (www.gprsurvey.com/practice). In the 3D display the individual transforms for each
level can not be adjusted as they can be for 2D overlay analysis operations
in the T-Slice menu, as a global transform is applied across the entire
volume. Nonetheless, visualizing the overlay analysis options in 3D provides
another way to present, observe and report adjacent and continuous
reflections with variable reflection depths.
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 1. Example of a Overlay Analysis slice generated through a 3D
volume using the new “O” button.
2) Assisted Auto-Hyperbola Detection and Mapping (Bridgedecks)
GPR-SLICE now has options to automatically detect hyperbolas and to
output these detected hyperbolas for mapping (e.g. Figure 2A, B). In the
Hyperbola Search menu, hyperbolas can be detected by
1) Setting the velocity of any discovered hyperbola using the mouse.
2) Setting the start and end sample of the pulses to run the search over.
GPR-SLICE V6.0 www.GPR-SURVEY.com
3) Entering a threshold and a N-threshold value which describes the
minimum binary amplitude response to detect for a hyperbola, as well as the
number of scans that the threshold is breached over the hyperbola.
4) Defining a parameter called N-skip to force the detection to wait this
number of scans before the detection filter becomes active again after a
hyperbola is found.
5) Auto-Search or Batch Search button is clicked to start the dection.
After the searching is run, a dialog showing the x, y, z position of the
detected hyperbola along with the amplitude are reported to the screen.
This information is stored in the file with the extension *.hyp in the \topo\
folder of the project for each radargram. The hyperbolas can be edited on
the screen or additional hyperbolas can be added using the mouse to insert
hyperbolas that were not optimally detected.
The options in the menu allow for using the peak+ or the peak– response of
the scan pulse.
In addition, cosmetic options to show or not show the
hyperbola tails beyond the N-threshold range is available in the menu, along
with scrolling options to target just a portion of the radargram are available.
Figure 2A. Auto-hyperbola detection and mapping is now available in the
Hyperbola search menu for authorized licenses.
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 2B. A second row of hyperbolas can also be detected on the same
radargram in Figure 2A. In this example a positive binary threshold of 5000
is set to optimally find the strongest and well defined hyperbolas on the
bridgedeck section.
3) Automatic bandpass filter design
The Bandpass Filter menu now has a help set button to assist the user in
drawing or setting a tapered spectral gain curve. Shown in Figure 3 is a new
button called “Help Set” which will draw a tapered curve based on the lowcut and hi-cut frequency bandpass settings. The tapered curve will be
drawn such that the low-cut and hi-cut frequencies are at half power points
on the spectral curve.
A recent update in the summer was also done to
increase the number of points for the spectral gaining to 40 so that hand
drawn curves could better generate notched filter designs.
Note, to set the low-cut and hi-cut bandpass, the right and left mouse clicks
are set in the graphic region where the power spectra is drawn. (These
settings are only used to assist in drawing the spectral curve and are not
used specifically in the bandpass filter. These settings however are used
directly for the spectral whitening filter where only frequencies within these
settings have magnitudes set equal to 1 – preserving the spectral phases.
Magnitudes outside these bandpass settings are set to 0.)
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 3. Bandpass menu showing the new Help Set button to automatically
draw the bandpass filter gain curve following the half power points of the locut and hi-cut frequencies.
4. US Radar GPR manufacturer support
US Radar is a manufacturer of GPR equipment (www.usradar.com). Ron
LaBarca, the president of the company, was recommended to GPR-SLICE by
the developers of ERA technology of the UK which was acquired by US
Radar. GPR-SLICE has been programmed to provide support for older US
Radar equipment under the ERA brand, as well as the newer US Radar
equipment currently being manufactured.
US Radar support buttons are
now available in the Convert and Edit Info File menus. Currently, two new
users with US Radar equipment at the University of Computense, Madrid,
Spain, and Hawaii Geophysical Services, recently signed onto the software.
According to Ron, he was "pleased with the results and the seamless integration that
we decided that we would recommend Slice to our customer base while we concentrate
our engineering efforts on other hardware based advances". GPR-SLICE will be
GPR-SLICE V6.0 www.GPR-SURVEY.com
recommended to all users of their equipment as their primary imaging
software.
As the number of manufacturers supported has increased, we hope to
simplify some of the menus in the near future by adding a manufacturer
equipment listbox.
With this set, we can just preview the relevant
manufacturer buttons in several menus including the Convert, Edit Info File
and Navigation menus.
Operational Notes: enhancing linear features from cross XY surveys
(e.g. rebar in concrete)
As many new users of GPR-SLICE are doing geotechnical surveys, it is
useful to show how rebar and concrete mapping options in the software can
be used to enhance linear features. For those doing XY surveys on concrete,
it is possible to decouple the X and Y lines, generate separate grid maps with
directional weighting, and then use grid math to add the decoupled grid
maps back to enhance linear features. Shown in Figure 5a is one time slice
made from lines parallel to X axis of a grid. To enhance linear features
transverse to the X lines (or better said, to “bleed” anomalies across to
adjacent lines) one can use x and y search radius which are unequal. In this
example the X search radius is minimized (to a value of 0.5 distance unit)
and the Y search radius is expanded (to a value of 7 distance units). The
net effect on gridding is to better connect linear anomalies going across the
lines. Similar operations are made for the Y lines of the grid (Figurue 5b)
with X search radius set to 7 and the length of the Y search radius which is
minimized to 0.5. After the decoupled grids are made, Grid Math is used to
add the grids back together (Figure 5C). Rebar mapping in concrete is
shown to be enhanced.
Comparisons can also be made using combined XY gridding which show
the linear features but not quite as well as the decoupled grids. Users can
practice on this dataset given in the Advanced Users Workshop folders on
the ftp site (\Kisatchie\concrete2\). In general, XY combined gridding is
better when there is no prior knowledge of what kind of structures are in the
ground. However, having prior knowledge can allow you to enhance these
features, particularly for linear structures that are primarily parallel to the x
or y directions
Note: A high cuts-per-mark setting of 10 in the Slice/Resample menu was
used in generating the spatial bins for the time slice ASCII datasets. This
will insure that a high density of bins is generated along the radargram.
The search radius along the radargrams was set to about 2.5 times the bin
width or 0.5 distance units (for enhancing the linear features transverse to
the radargram direction).
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 5A. Grid settings used for making time slices of just the X line data.
(Data courtesy of Ron Crowson).
Figure 5B. Grid settings used for making time slices of just the Y line data.
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 5C. Grid math operation to add time slices made from decoupled X
and Y lines to generate X+Y time slices.
6) Miscellaneous improvements:

2D perspective button in Open GL Volume to show flat perspective in X
and Y planes as well as X. This option is useful for making 2D output
from the 3D volume display. The 2D perspective button should be
clicked to toggle to the desired X, Y, or Z perspectives. An example of
using the Open GL Volume (Topo Warp Volume) menu to display even
a radargram in a 2D perspective is shown in Figure 6.

Multi-channel support for the IDS of Italy Stream arrays has been
included in GPR-SLICE.

Browse button added to the New Project creation for quickly setting
any existing folder/subfolder designation to place the new survey.

Z axis labeling tilting of 90 degrees added to Options menu for Open
GL Volume viewing.

UTM Get XY button provided in the Edit info File menu to import a file
called utmgetxy.dat which can reside in the project folder and contains
no header and simply x0,x1,y0,y1 comma delimited lines. This import
option is useful for users that often have excel files or other files
containing UTM coordinates of start and end points of GPR lines for
import to ANG surveys.
GPR-SLICE V6.0 www.GPR-SURVEY.com
Figure 6. 2D perspective switches are available for X, Y and Z planes to shut
the perspective off the 3D volume and allow for 2D flat perspective displays
for any volume element, including radargrams, to be shown.
For those using ANG survey definitions where angled straight lines or
fractional line lengths surveys are used, should use the ANG, X, Y, XY to
Vector button in the Edit Info File menu to convert this survey type to the
generalized Vector survey navigation. This is a requirement particularly if
you want to use the Time Slice – Radar or Radar – Time Slice split screen
capabilities where choosing anomalies will show the corresponding anomaly
location in the other data domain.
There were numerous bug fixes all of which are listed on the Subscribers
Only page of the website.
Recent Events and Upcoming Events:
We had 17 attendees come to the Advanced Training course in Woodland
Hills including Justin Klein. The list of users that attended included:
GPR-SLICE V6.0 www.GPR-SURVEY.com
Bill Steinhart, Enviroscan Inc, Pennsylvania
Jennifer MacDonald, Worsley Parsons, Calgary
Linden Graham, Worsley Parsons, Calgary
Bereket Derie, Round Rock Geosciences, Texas
Derek Braun, Seminole Tribe of Florida
Ron LaBarca, U.S. Radar
Joerg Clausen, U.S. Radar
Beverly Chiarulli, Indiana University of Pennsylvania
Mitch Jack, Muscogee Nation
Charles Kelly, Muscogee Nation
David Tillson, Consultant, Salt Lake City, Utah
Aaron Fogel, Environmental and Historic Preservation, FEMA, Mississippi
Janet Simms, United States Army Corps of Engineers, Mississippi
Skyler Robinson, Choctaw Nation, Oklahoma
Bill Silva – Sacramento, Caltrans
Monica Guerra, Hawaii Geophysical Services, LLC
I received a lot of positive feedback on the workshop and many new and
old users found the workshop very useful. Just like all the workshops
however, we always end up trying to cram too much information in the last
few hours. Our motivation is to let you know what the software is capable of
doing - and of course the details can be discovered again. As subscribers I
am always available for telephone conferences.
We also hope to offer a workshop in the spring time and we will let you
know further about this possibility. An advanced workshop will be scheduled
in conjunction with GPR 2010 in Leece, Italy in June 2006. We will also let
you know about this schedule as it is formalized.
I will be traveling in Japan from December 12-29 on an invitation to
participate in surveys at the Imperial Family Tombs in Miyazaki in
conjunction with the Saitobaru Archaeological Musuem, as well as a small
project in Shizuoka prefecture. Please allow an additional 24 hours for any
email support during this period.
This newsletter is available for download on the Subscribers Only page.
Best wishes, Dean
Note *** All users must make the update of GPR-SLICE before
December 31, 2009 for uninterrupted service ***
GPR-SLICE V6.0 www.GPR-SURVEY.com