Newsletter - November 2013
GPR-SLICE users,
I would like to welcome the following organizations to the GPR-SLICE
community
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Dept of Anthropology, University of Northern Colorado
Nakano Technology Co., Ltd., Saitama, Japan
Dept of Classics, University of Cambridge
Dept of Civil Engineering and Geoinformation, Oldenburg University,
Germany
Terraprobe, Burnaby BC, Canada (www.terraprobe.com)
Dudek and Associates, Encinitas, California (www.dudek.com)
Terrasond, Palmer, Alaska (www.terrasond.com)
Informatic and Information Security Research Center
Tubitak Bilgem, Turkey
TAG Research by Sturm Inc, New Mexico (www.tagrsi.com)
Buyeo National Research Institute of Cultural Heritage, Korea
Connected Water Initiative, University of New South Wales, Australia
Cultural Resource Consultants LLC, Anchorage, Alaska
Bronx Community College, CUNY, New York
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Geonorm
Project
Engineering
Consultancy,
Turkey
(www.geonorm.com.tr)
Tongva Ancestral Territorial Tribal Nation Consulting, California
Dept of Mining Engineering, McGill University, Canada
In addition, GPRSIM licenses were delivered to Dept of Earth Sciences,
University of Toronto, Canada; Dept of Civil Engineering and Geoinformation,
Oldenburg University, Germany; Guangxi Communications Investment
Group Co., Ltd, China; Jiangsu Testing Center for Quality of Construction
Engineering Co. China; Tubitak Bilgem, Turkey.
Software Updates
Among the most important improvements added to GPR-SLICE V7.0
Software are:
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Navigation markers inserted directly on the \radar\ folder
Slice/XYZ operation for working with native density radargrams
2d/3d Kirchoff Migration added to filter menus
Improved auto hyperbola detection options
0 median grid mosaic correction
User defined labeling - scan header labeling override for ANG surveys
Navigation markers inserted directly on the \radar\ folder
The title of this new option "Navigation markers inserted directly on the
\radar\ folder" may seem strange but it has significant meaning for
streamlining operations in GPR-SLICE. Historically, since the inception with
GPR-SLICE for DOS, navigation was only placed on the radar scans after
slice/resample operations were completed.
The \resample\ folder
radargrams contained navigation tags in the 2nd sample of the radar scan
and only on these radargrams or radargrams processed from this folder,
could navigation labeling be available. GPR-SLICE axis labeling requires
navigation tags to exist on the radar scan in order to obtain a drawn
label. GPR-SLICE operations now directly place the navigation tags on the
scan headers in the \radar\ folder (Figure 1). The operation is only run one
time on the \radar\ folder after which the Navigation menu never needs to
run again. Previous GPR-SLICE applications required always returning to the
navigation menu to apply navigation prior to running slicing operations on
any processed folders.
Also, had user tried to display \radar\
folder radargrams, no axis labeling would appear since navigation tags did
Figure 1. The new look in the Navigation menu where only the \radar\ folder initially has
navigation applied only one time for all processes.
not exist on the \radar\ folder for survey wheel or GPS collections. Field
marker radargrams would show axis labeling as the tags natively exist in the
radargram scan header
Note: Previously, all operations for slicing would look at a file called the
\marker\*.mrk
files
which
were
generated
when
running
the
navigation. These files contained the list of scan numbers in the radargram
where xy navigation is known. These files most did not know existed as
they were in a separate folder inside all projects and never directly
accessed. The \marker\*.mrk files are now not used although still being
written. The marker tags directly stored in the radargrams are read
internally wherever operations requiring the scan numbers are needed, such
as in slicing operations or xypoints etc.
Note: For users that navigate a survey with field markers and do not use
survey wheels or GPS, only the Field Markers operational button should be
clicked in the Navigation menu. Clicking the Artificial Marker operation for
instance will erase the field markers in the converted radargrams. If this or
any other navigational options such as Interval Markers or GPS navigation
buttons are accidentally clicked, the user will need to reconvert the
radargrams from the Convert menu in order to see the original field
markers.
The idea to place navigation tags directly onto the radar scans in the
\radar\ folder initially - rather than requiring resampling operations where
marker tags are assigned, came about as several users asked about using
the native radargrams without having to resample the radargrams,
especially for data collected with a survey wheel for instance.
By placing
the tags into the \radar\ folder radargrams, working with the native scan
density collected on a site from a survey wheel is now available. This
discussion takes us to the next major operational option now in the GPRSLICE software:
Slice/XYZ operation for working with native density radargrams
Figure 2. Slice/XYZ operations were no resampled radargrams are generated are now
available for working with only the native density radargrams.
With the application of placing navigation tags into the \radar\ folder
radargrams, the necessity to resample radargrams is no longer a
requirement. Users can now simply run the Slice/XYZ operation and never
need to generate the \resample\ radargrams if so desired (Figure 2). For
those that are concerned about using only the native radargrams then this
button may be the operation of choice. Resampled radargrams of
course have advantages such as a constant number of desired scans
between recorded navigation tags which can make 2D displays often
more visually desirable. In any event, if a user chooses a proper
resample/scan value then resampled radargrams will always have the same
resolution in the native - recorded radargram.
Restating these two latest options added to GPR-SLICE for streamlined
operations are:
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markers tags are now stored directly in the scan headers in the \radar\ folder
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navigation only needs to be run one time initially on the \radar\ folder
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processed folders from the Filter menu do NOT need to have navigation reapplied
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native scan density \radar\ folders from can now be used for all processes
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\resample\ folders will continue to be made and can also still be used for all
processes
Note:
BlueBox Batch operations
currently still contain
resampling
operations. We may see about providing options for working with native
scan density radargrams in the future for BlueBox operations.
Improved auto-hyperbola search function
A new algorithm to automatically detect hyperbola on radargrams has
been advanced (Figure 3). The new Autosearch2 button will engage a 5
point search. The search will look along a horizontal line from the mouse
location which is typically placed near the apex of the hyperbola. Normally
you will want to place the 5pt search line on the 2nd pulse of the return and
center it. If you do this and properly adjust the migrator width, the
software will set amplitude thresholds automatically on the center, points
1/4 and points 1/2 the total migrator width on each side. If you choose a
proper migrator width, the outside points (#4 and #5) will have the opposite
signs then the inner 3 points. Searching the hyperbola with this algorithm
Figure 3. Location of the new automatic hyperbola detection operation for examing 5 pts
across the hyperbola apex.
has proven to work significantly better than the scan/threshold method
which is still in the menu. The operations are to click the Help 5pt button,
move the hyperbola/line to the desired location, then left click the
mouse. This will update the search parameters dx1-5 which are the nearby
scan locations from the center, dy1-5 are the horizontal samples on the
pulse, and a1-5 are the amplitudes at the 5 points. The amplitudes a1-5 are
decreased from the actually amplitudes at those locations. The point a1 is
stored as .8 of the detected value, a2-3 are recorded as .5 and a4-5 are
recorded as .25 the actual recorded values to insure that amplitudes of
slightly weaker hyperbola can be detected. These slots can be manually
adjusted as well. The dy1-5 slots are always shown as 0 for the help 5pt
search. However, these can also be adjusted by the user for a more
customized search. For instance, searching a Hilbert transform-migrated
radargram, one might one to have a vertical search on the pulse to isolate a
strong anomaly etc.
Note: Autosearch2 still requires one to set the N-Skip and the N-Nearby
settings. The N-Nearby setting will automatically look N scan to the left and
right, and N samples up and down from the first detection location to find
the peak response from the initial detection. The N-Nearby functionality is
also engaged should the user want to manually insert hyperbolas into the
detection window. A value of 0 on the N-Nearby would yield exactly the
detected location; values of 2-4 can assist in making the detected hyperbola
more centered on the feature. There is also new setting call S-Backup. S-
Backup will move the drawn hyperbola N samples on the pulse. S-backup is
used to predict the first arrival of the wave and not the peak response, to
give a better estimate of the depth to the top of the rebar. Even though the
S-backup is engaged, the value of the peak response is reported and not the
value where the hyperbola is drawn if this options is set to other than 0.
Kirchoff migration
Figure 4. Kirchoff migration operation in the 2D Filter menu.
The first migration routine provided in GPR-SLICE was diffraction
stacking of the recorded hyperbolic reflections (sometimes referred to
as simple hyperbolic summation).
An improved migration routine Kirchoff migration - that works similar to hyperbolic summation but accounts
for amplitude adjustments for spherical spreading of the radar wave and also
the obliquity of the wave on its arrival to the ground surface is now available
in the Filter menu for 2D and 3D processing. (Figure 4) The Kirchoff
migration is the recommended migration routine and it performs better than
simple diffraction stack migration. This routine also does not have any edge
effects at the bottom of the radargrams as spherical spreading adjustments
will properly weight the diffraction stacking of amplitudes in the migrated
pulse (as seen in the example in Figure 4) .
0 Median grid mosaic correction
Figure 5. 0 Median grid and 0 mean grid operations buttons are now available in the Mosaic
Correction menu.
A new algorithm to try and automatically correct mosaic correction has
been added to the stand-alone Mosaic Correction menu (Figure 5).
The
operation works by calculating the median value of each defined grid division
(defined in the info menu) and then normalizing all the blocks by their
median value.
For certain kinds of surveys noises the median grid
algorithm may work to balance the different survey blocks. This method is
best suited to surveys where the distribution of data are similar in each of
the blocks. e.g. the same number of weak, medium and strong anomaly
areas are about the same density in each of the blocks.
0 mean grid
operations are also now provided in the stand-alone Mosaic Correction
menu. To properly view the 0 median corrected grids the user should run
the operation on grid #1 so that this grid set will appear in the Pixel Map for
further viewing an display.
The Regrid option can also work very effectively in the menu to adjust
mosaic noises real time. In this operation, the user sets the desired block
with the div+/- button, adjusts the gain or the dc offset to balance the data
with a nearby block, then uses the Regrid button to re-grid the *.dat using
the adjustments. In this method, while applying the gain or dc adjustments
to the actual grid, edge effects will be seen in the drawing along the block
edges. This is to be expected since the gridded data at the edges were
generated
with unmatched
searched
data
from
both
nearby
blocks. However, on re-gridding, the original *.dat is used to recalculate the
grids and those edge effects will not be present after the operation.
For 0
median and 0 mean grids, new *.dat and *.grd data are generated with the
"0m" appended identifier. For the Regrid option, the *.grd is overwritten
with the original name. For 0 median and 0 mean operations and the
Regrid option, the original *.dat must exist for the corresponding displayed
grid file. Direct gaining on the *.grd file real time with writing to the
"m*.grd" file is available and does not require *.dat data to exist.
User defined labeling - scan header labeling override for ANG
surveys
GPR-SLICE has traditionally only outputted labeling on 2D radargrams
that comes from the scan headers where navigation tags are stored in the
2nd sample of the digitized pulse. This has been a double check on
navigation - as only tagged scans can force a label in the radargram
displays. Even if a radargram is defined as some length in the info.dat file
and there are no navigtaion tags in the radargram scan header that were
applied through the Navigation Menu, no labels will appear on
displays. For ANG surveys, where there can be fractional line lengths, the
navigation
tags
may
not
be
at
integral
lengths
in
the
radargrams. Navigation tags for ANG surveys can be at non-integral
lengths. The reason for this is in the process of creating time slices and a
need to properly include and equal weight all portions of the radargram in
the time slice binning process, tags are set at non-integral locations. For
instance a 10.0 meter radargram, would get tagged with 11 navigation tags
but a 10.43 metter radargram for would get 12 navigation tags (including
the scan #1). The user would be able to break down the 12 tags in the
radargram with the Cut Per Mark option to generate additionally smaller bins
for time slice operations. With that said, because of the non-integral
location that can occur with ANG survey for the tagged scans, on displays,
the labeling will show at fractional numbers. This also requires that the # of
decimals in the x axis display be set to something other than 0. Several
users complained that they could not get out equidistantly labels at a desired
graphic increment. For this reason, an old option that was taken out of the
software has been re-instated (Figure 6). The Big Tick frequency, if set to a
negative value in the Options menu, will override the scan header navigation
Figure 6. Location of a flag for overriding scan header tags and customizing labeling to any
interval desired (normally for ANG defined surveys).
- and provide a completely graphical labeling where the user can control the
interval between labels.
An
that is
option
labels
example of a traditional scan header labeling for an ANG survey line
10.43 m and what can be achieved with a negative Big Tick frequency
is shown in the following figure.
In the traditional ANG survey, the
have fractions in them. With the override engaged the user can
achieve any integral display on the tick labeling. The tick labeling interval
can also be sub-integral if desired by clicking off the Automarker labeling
checkbox in the Options menu.
Note: Scan marker override option is only available for X, Y, XY or ANG
surveys and is not applicable or available for GPS surveys.
Other features and options added to GPR-SLICE include:
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Tiff image export and world file TFW extensions added to the Pixel
Map menu
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Double precision of writing dxf object file in OpenGL Volume with
UTM or large coordinate offsets
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Lat/long and lat/long decimal range display options available in the
OpenGl, Radar 2d menu and the Pixel Map menu
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Front and back label reverse location display in OpenGL
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OpenGL 2+ labeling places front depth label in back of volume
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GPS log filename extensions setting option available in Create New
Info menu to allow for various custom logging conventions
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Import XYZ point file into OpenGL Draw
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Active projects dimension increased from 500 to 5000
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Warning message box on double GPS points and Double GPS scan#s
on GPS log file conversion in the Edit Info FIle menu along with
recommended filtering in the GPS Track menu
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+/- time slice scroll buttons added to Multichannel menu for large
areas and in the regular 2D Pixel Map menu
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Append option added to TSpoints
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TSpoints in the 2D Pixel Map menu importable in OpenGL Volume
Draw menu
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Import Geodata, xzyd format added
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Grid division between two time slice datasets added to Grid menu
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DXF negative z elevation and undo/redo buttons added to OpenGL
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Auto deletion of decrementing scan numbers in GPS log files
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FK radargram filtering - beta version working for small files with
scans less than about 2000
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Append identifier to rename a set of truncated radargrams added to
the Radar Edit menu - useful for separating Dual Frequency
radargrams written double long
In addition, many minor and several important bug fixes were made and
all users should download the latest software.
Note: All users will need to update their current version of GPRSLICE to insure their software will launch after January 1, 2014.
Supplemental manuals and/or Powerpoints discussing in more detail
operations in GPR-SLICE are now available on the Subscribers Only page of
the website. Two supplemental manuals are currently downloadable and
discuss:
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Vector Radial Tunnel Operations in GPR-SLICE
Importing and Displaying EM data in GPR-SLICE
On the multi-channel page of the website a new supplemental is available:
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GSSI SIR 30 Operations in GPR-SLICE
Recent and Upcoming Events
GPR-SLICE workshop class from Sept 28-29 was taught by Dr. Alex Novo
in Montreal and was attended by 10 people from coming from Brazil, Canada
and the US. Alex has scheduled be a 2 day GPR-SLICE workshop in
Pontevedra Spain the University of Vigo from December 18-19,
2013. Details on this workshop are available on the Upcoming
Events page of the website and our facebook page. The dates for 2 day
workshop in February in Woodland Hills California will be scheduled shortly.
20th Anniversary of the Nutubaru Kofun Survey
For those that are not familiar with the origin of the GPR-SLICE logo, it
came from a survey Koji Tobita and I did back in 1993 with Yasushi
Nishimura from Nara National Cultural Properties Research Institute, and
with Hiromichi Hongo and Noriaki Higashi from Miyazaki Prefecture Dept of
Archaeology in a field in Shintomimachi on the island of Kyushu in
Japan. In these days we were still working with analog equipment and 16
mb tape drives and 50 m antenna cables in the field!
It
was not so streamline to collect data as we required gas field generators
required to power the equipment as well as experiencing recording issues
and missed data records on magnetic tape. The yellow plastic tape on the
control unit was to insure that the analog gain controls did not inadvertently
get changed which could mess your day up. A 2 day filed survey on
November 12 and 13 was batch processed on the evening on the 13th and
into the early next morning. We woke up to see an unexpected perfectly
round anomaly, 22m across from a 6th century destroyed - Kofun period
burial mound. The strong feature inside the round moat is a collapsed burial
chamber. The results were published in the Miyazaki Shimbun on November
14. Up to this point in our limited GPR experiences our lab had yet to see
such a beautiful image which clearly indicated that we could discover a lost
structure that our ancient ancestors had built.
The 20th anniversary of the image taken on the Nutubaru Burial
Mound is this month. Time flies!
cheers...Dean
Dean Goodman
Geophysicist, Phd
GPR-SLICE Software
Geophysical Archaeometry Laboratory Inc.
dean@gpr-survey.com
gal_usa_goodman@msn.com
www.GPR-SURVEY.com
facebook: https://facebook.com/pages/GPR-Slice/124352290972979?ref=hl
*This newsletters is available in *.doc form on the Subscribers Only page of the
website