Newsletter – April 2007
GPR-SLICE Users,
I would like to welcome 5new organizations to the GPR-SLICE community:
Southern Illinois University
Radarteam, Sweden
Universidad Politécnica de Cataluña, Barcelona, Spain
Wiebe Group, Geo-Rail Division, Germany
GeoSurveys, Portugal
Dr Harvey Henson from the Department of Geology evaluated GPR-SLICE for several months after hearing good things about the software. Harvey is our first subscriber in Illinois. His applications are in geologic as well as archaeological surveying.
Per Wikstrom is the president of Radarteam in Sweden. For those that do not know Radarteam(www.radarteam.se), this companydesigns and developments radar systems and antennas, some of which are being sold by GSSI in New Hampshire as part of their systems. Perhas taken a subscription of GPR-SLICE and GPR-SLICE View. He also has an interest in offering GPR-SLICE for their new 16 frequency sled radar system which they will be marketing shortly on their own.
Vega Perez Graciafrom the Dept. Ingenieria del Terreno, cartográfica y geofísica at the Polytechnica Universidad de Cataluña in Barcelona, was introduced to the software by Henrique Lorenzo at the University of Vigo. I had a chance to meet up with Vega in Barcelona on my last trip to Spain and introduce the softwares to here. Roger Sala from SOT Prospeccio has also graciously trained Vega in the subtleties in the software processing on his. Her university signed on to the softwares are subscribing to GPR-SLICE, VIEW and GPRSIM.
Daniela Hofmann from the Geo-Rail Division of Wiebe Group became the first subscriber to begin using the multi-channel array options in GPR-SLICE. Daniela's company owns the GSSI Terravision and have needed toemployGPR-SLICE in orderto manage this unique dataset. Special buttons open up in the software for multi-channel licenses so most of you will not get to see these options for you license. Daniela is planning a large survey in which over 10,000 lines of multi-channel profiles will be collected and processed in the software. Daniela also took a subscription to GPRSIM.
Helder Teraco who is starting a new company in Portugal called GeoSurveys, is just finishing up his Phd at theDepartamentode Geociencias, Universidadede Aviero. I never had chance to meet or talk with Helder, however, he was recommended to GPR-SLICE by the Mala Geoscience of Sweden in order to have the capability to image nonlinear survey grids. That is a great sign that this SwedishGPR manufactureris helping their equipment users meet their software needs by recommending GPR-SLICE.
We welcome all the new users to the software community.
Updates:
Several very important updates for GPS/GPR surveyswere implemented into the software at the request of users.The following updates to GPR-SLICE v5.0 are now on the website:
1) Revamping of the *.*.gps file to replace date designation with GPS elevation
2) NewGPS operations in the Static Corrections menu to read the GPS elevation and topographically correct GPS radargrams
3) Renaming of SS to UTM button to lat/long to Nav, SS to Nav renamed to Nav0 to Nav
4) Automatic detection of grid divisions for mouse mosaic correction menu
5) Cosmetic labeling for 2D radargram and 2Dtime slicedisplaysadded to Options menu
6) Parallel port executables are decommissioned - GPRSLICEV5.exe is the name of the new executable (for USB key security)
1) As was discussed among the GPR/GPS GPR-SLICE community, the need to expand the gps files was easily accommodated by replacing the date with the GPS elevation. Daniela Hofmann Geo-Rail in Germany asked that the GPS elevation correction be implement for their radargrams collected with a Terravision multi-channel radar unit. Rather than start a completely new *.*.gps file format., it was simple enough to remove the date in the 3rd column and replace this with the GPS elevation. The new format that one must create is
eastings, northings, elevation (m ), "time", scan #
An example file is shown below:
504784.008404931, 5874025.08523329, 64.1549987792969, "13:25:31.00", 1
504783.983005655, 5874025.1037484, 64.1589965820312, "13:25:31.40", 11
504783.936593125, 5874025.11519728, 64.1600036621094, "13:25:31.80", 21
...
Eastings, northings and elevation in meters are read in as double precision variables. The timewhich is recorded with quotes around it hasbeen expanded to include milliseconds or hundredths of seconds depending upon ones GPS system. The original GPS file formats were only created to the nearest second. In the above example with the new format,the seconds are given to0.01 seconds.Some GPS systems will have the NMEA string time given in milliseconds. Either import can be made into GPR-SLICE. Time is currently used in operations where the user has GPS fallout and they wants to interpolate GPS reading between recorded points. The GPS interpolate time option in the track menu currently will only look for integral seconds and find where portions of the file are missing more than 1 second of data. If users see a need to interpolate at sub-second readings please let me know and we will have to look at putting in options in the software to do this.
For those Sensors and Software users, you probably have noticed no difference since GPR-SLICE will automatically extract the elevationfor the $GGCPA NMEA string. For those GSSI users that are making their *.dzt.gps files on their own, please replace the3rd columndateentry with the GPSelevation. If you did not collect elevation in your survey simple set the third column to a floating point number such as 0 - do not leavethe datein the file with quotes as this can cause input errors for someoperationsin this latest version of GPR-SLICE v5.0.
The 5th column which is the scan # must not repeat itself and must of course be increasing. Recently, a datasetfromGeo-Rail that had the GPS file generated had 4-7 points with constant scan numbers. This occurred in their GPS file because they are using 10HZ recording and the buffering in the GPS logger was such that the scan number would not get incremented till about a half second or so. The Del Double GPS button in the GPS track menu has been modified to also remove double or multiple scan numbers in addition to multiple replicated GPS eastings and northings values.
2) GPR-SLICE now has operations to read the GPS elevation and make corrections for this in the Static Menu. Shown in Figure1 is the revamped Static Menu to accommodate automatedGPS elevation corrections for batch operations. Clicking the Extract GPS/Nav button will make the necessary elevation file for correction that is used. The file that is generated is dependent upon the samples/scan and the velocity that is set in the menu as well. An example of the correction is shown in the Static Corrections menu. When the correction is being implemented, a real 2D radargram will be shown (Figure 2). However, the GPS radargram may actually trace out a 3D path. To see the complete 3D GPS radargram with topography, you will need to display it in the 3D GPS Radargram menu (Figure 3). The user also has the option to compile all the GPS elevation information for all the radargrams in the project into an xyz topo1.dat file and then grid this to obtain the topo1.grd. The topo1.grd file can be used todrape 3D rectangular volumes into the topography for a site.
3) We are starting to standardize GPS related information and to connect these datasets with surveys in which total station or other UltraWideBand or laser navigation is being used. Several of our users are now foregoing GPSand using tracking systems which give much more accuracy and can be used in wooded areas or even inside buildings. To generalize navigation we have renamed 2 buttons in the Edit Info File menu to reflect the changes.The SS toNav button has been renamed to lat/long to Nav and the SS to Nav button has been renamed to Nav0 to Nav.
The lat/long to Nav button will now take a*.gps filewith the format:
Trace #1
$GPGGA,121904.40,5136.1319966,N,01228.2666311,E,1,06,2.4,87.488,M,,,,*03
Trace #7
$GPGGA,121904.50,5136.1319827,N,01228.2666212,E,1,06,2.4,87.482,M,,,,*0E
Trace #17
$GPGGA,121904.60,5136.1319681,N,01228.2666114,E,1,06,2.4,87.474,M,,,,*03
....
and generate the *.*.gps:
324868.692104053, 5719825.10702795, 87.4879989624023, "12:19:04.40", 1
324868.6797875, 5719825.08166426, 87.4820022583008, "12:19:04.50", 7
324868.667541448, 5719825.05499935, 87.4739990234375, "12:19:04.60", 17
...
where the *.*.gps is *.dzt.gps for GSSI, *.dt1.gps for Sensors and Software, and *.rd3.gps for Mala.
Because Geophysical Survey Systems and Mala Geoscience have yet to make any standardized GPS formats, we are currently going to ask other equipment users to follow the Sensors and Software format which these buttons were originally named for. Most of our GSSI users are already making the *.dzt.gps files on their own. The only change you need to be aware of is that the 3rd column is now elevationand not date!
The Nav0 to Nav button was named for the total station tracking where the files arewritten exactly as they are in the *.gps file as shown above, but the latitude and longitude are replaced with actual localgrid coordinates from thetracking system. The Sensors and Software users are now getting these identical file formats so the only difference in creating the *.*.gps files is that UTM conversion is notrequired. The Nav0 to Nav button reads the *.gps file andrewrites it into GPR-SLICE *.*.gps format by simply extracting the x and y coordinate directly from the total station "NMEA" string.
I had briefly discussed a few of these namingissues late last year with Erik Kitt at 3D Geophysics and he recommend generalizing the navigation for GPS and total stations with the Nav identity.At first Iwashesitant but aftermonth of thoughtand dealing with total station data I came up withthesame idea that Erik suggested!.
Again, Sensors and Software formats I believe have led the charge in implementation of standard and clean GPS and total station navigation file format. Unless the other companies make some of their own proprietary formats that are "permanent" we are asking everyone to follow the above formats. Most of the GSSI people are directly making the *.dzt.gps files on their own. However, if you want GPR-SLICE to handle UTM conversion or extraction of the $GPGGA NMEA string then you need to make the *.gps file in order to use the lat/long to Nav utility.
4) Carl Lipo from Cal State University Long Beach suggested that the Mosaic Correction operations could be sped up ifGPR-SLICE could automaticallyrecognize the multi-grid divisions set in the Edit Info File menu. Carl wanted the Mosaic Correction menu to be able to automatically highlight the rectangular regions within a multi-grid survey to have gain corrections applied. If the division file is saved with check marks delineating grid divisions in a large information file, these divisions can now be accessed with new buttons that appear in the Mosaic Correction menu (Figure 5). Clicking the Div+/- buttons will highlight the specific grid divisions allowing the user then to manually adjust the gains or dc offset for these areas to try and match the gain. Remember, mosaic corrections via screen capture will still have edge effects. To minimize these problems it is good to apply the mosaic capture and correction with unsmoothed-raw grids and then to apply a smoother, e.g. a 3x3 or 5x5 low pass smoother to the corrected grid to blend in the edge effects between adjacent grids. In general, the other method of Transform matching for mosaic corrections will normally always give slightly better results and edge blending, although it is much more time consuming to correct a multi-grid for mosaic noises.
5) Additional labeling of axes in 2Dtime slice and radargram displays is now available in the Options menu (Figure 6). For multi displays and depending on if a very thick font weight and widths are being used, some overdrawingcan occur. In these instances, the user may need to place the auto display onto the custom setting and shift the plots accordingly to accommodate large and thick font settings so the plots do not overdraw. Leaving the labeling information blank will give the traditional labeling displays where only the distance and the time unit are written very compactly next to the time and first x axis coordinate. The labeling additions are currently available only for 2D radargram and 2D time slice displays. In addition, an optional dual depth label for 2D radargrams will be placed into the next GPR-SLICE update. The slot for this however is already in the Options menu but is not yet activated.
6) The last parallel port key executables were decommissioned this week. We no longer are creating secured copies of the software with the -parallel extension. Also in this regard the GPRSLICEv5-USB.exe is now being renamed to simply GPRSLICEv5.exe. Please make sure to update your shortcut on your desktop to this new name!
The latest updates are availableon the Subscribers Only page of the www.GPR-SURVEY.com website, password "Gypsy Ln".
Upcoming Events:
GPR-SLICE and GPRSIM will be exhibited at the SAGEEP conventionhttp://www.eegs.org/sageep next week in Denver from April 1-4.For those users attending the SAGEEP convention, I will make myself available in the evening to answer any specific questions or to run some brief training sessions at your request. You can also come by during the slow times at theexhibit booth.
GPR-SLICE and GPRSIM softwares will also be on display at the Society of American Archaeology meeting in Austin next month from April 24-29 https://ecommerce.saa.org/saa/staticcontent/staticpages/meetings/exhibitors.cfm. I invite all those usersthat plan to attend this meeting to also come bythe booththere as well.
Dr.Robert McCullough has opened up his GPR workshop from July 9-11 at the Indiana-Purdue Archaeological Field School in Indiana to all interested parties. Since 2005 we have been training undergraduate students in GPR and GPR-SLICE processing. This new expanded workshop will be 2 dayevent which will include a full day of GPR-SLICE software training where all attendees will process data collected at the Strawtown Archaeological site http://www.ipfw.edu/archsurv/strawtown_geophysical.html. This workshop is a fee based workshop. If you have an interest to attend please contact Dr. Robert McCullough .
The University of California Santa Barbara will be running a GPR training session on the island of Santa Cruz http://www.unex.ucsb.edu/continuingeducation/courses/gpr/. For those of you that are interested please contact Steve Koppenjan or Lili Byall . Steve Koppenjan of Bechtel Corporation was the organizer of GPR 2002, Dr. Michael Glassow from the Dept of Anthropology at UC Santa Barbara, Bill Silvawho isthehead archaeologist for the CaliforniaDept of Transportation, Larry Conyers of the University of Denver, and myself will be instructors for the workshop.