Issue 3 - May - June 2007

    www.zupt.com

          INERTIAL NEWS
 

OTHER NEWS:

• BBC: Galileo system 'in a deep crisis'

Europe's proposed satellite-navigation system, Galileo, will need more public funds if it is to be built.

Hope is receding that a private consortium asked to run the system can end its infighting and meet a 10 May deadline to move the project forward.

This is likely to mean European taxpayers stepping in to cover costs. news.bbc.co.uk

Is this the reason why the UK may impose more GNSS based congestion charges?   Manchester evening news

• European Exports Regulations.  8th Annual Report of THE EUROPEAN UNION CODE OF CONDUCT ON ARMS EXPORTS: eur-lex.europa.eu

• D-TRADE Web Site of the US State Department… Only D-Trade Electronic Submissions as of April 30, 2007

As of April 30, 2007, the Office of Defense Trade Controls Licensing no longer accepts the “carbon paper” and “downloadable” DSP-5, DSP-61, and DSP-73 application forms. The D-Trade (electronic) version of these forms may only be used, and must be submitted through D-Trade.
pmddtc.state.gov
 

• Elephants everywhere... (5/29/2007) It was reported a herd of hundreds of wild elephants has been discovered in Sudan's swampy south where oil and gas exploration is in a planning stage... (OGI news).
 

• Sudan by the way is China's largest overseas oil project... http://www.hrw.org/reports/2003/sudan1103/26.htm

REMOTE SENSING TIPS:

Inertial technology -even ground based- is of great use for aerial photography, Lidar and remote sensing tech-niques.

• There is no need for crosses on the ground when an inertial system is integrated within the aerial camera: each pixel is already given a 3D position “on the fly” (direct georeferencing). But when a ground check is needed, with modern high definition cameras some details can be located on the ground in canopied areas, where the opening is not sufficient for a GPS survey. Inertial can survey those points (see that manhole, between those branches?) with great accuracy…

• To ground truth a Lidar survey over woods, one simply needs to drive the roads and trails of the project with an inertial system on board the vehicle (or walk it) …


• In GPS-Denied intervention scenarios, crews with inertial trackers can be followed on aerial images or video overlays in real-time while progressing inside buildings, underground or under water. They can in turn see themselves on the same overlays as they go, for total awareness…


• Glossary. Boresight Angle. The boresight angles of an aerial photogrammetric sensor are the angles between the axes of the sensor and the axes of the IMU mounted on or near the sensor. The term comes from traditional firearms where the angle of the sight is in theory never perfectly equal (or aligned with) the angle of the bore of the gun barrel. In order to “shoot straight” at short ranges, it was important to minimize this "bore to sight" angle. “Boresight” angle now means any angle between an orientation system such as an inertial system, and the device it is meant to orient. By the way, at longer ranges nowadays, artillery pieces use inertial systems to orient themselves ballistically on the fly.

 

INERTIAL SURVEY TIPS:

• Easy does it… however eager an operator might be to go straight through the bush, and fight “mano a mano” with the vegetation and the terrain, the best way to survey with an inertial system is to be a smooth operator...

• GPS surveyors do stay away from the forest where the high frequency GPS signal is badly affected, and usually blocked all together. Theodolite surveyors setup their instrument and patiently direct their rather large brush-cutting crew to create a wide and straight line in front of them before they can shoot their sideshots and foresight, change setup, and progress unhindered along a clean path.

• In comparison the Backpack Portable INS operator faces the forest on his own or with minimal cutting crew (1 man?). He can walk between trees, bushes and vines and deliver a survey production 3 or 4 times superior to his “optical” friend. The temptation is there to show his stuff and fight his way through the outback…

• It is much better though, to go slowly and walk around, to disengage from branches and thorns with some “suavity”, and to minimize dynamics. When less exhausted, the operator will breath easier during regular stops (Zupts), and the inertial navigation system in his pack will be submitted to less dynamics, less motion (less rotations, less accelerations), and the traverse will tie that much better.

• And like the study in “Survey Info” hereafter shows, the final results will be similar to what RTK GPS obtains in the open and mixed areas, with a productivity many times superior to “optical surveys” in the bush…

 

SURVEY NEWS:

• Topcon Agrees to Purchase Hayes Instrument
May 10, 2007

LIVERMORE, CA -- Topcon Positioning Systems, Inc., (TPS) announced it has signed a binding agreement to acquire one of the company's top survey products distributors, Hayes Instrument Company of Shelbyville, Tenn. The agreement includes an all-cash purchase for an undisclosed amount. topcon.com .

• Hexagon Acquires Allen precision Equipment…
May 4, 2007

Hexagon has entered into an agreement to acquire all outstanding shares of the American company Allen Precision Equipment, Inc. allenprecision.com.

• Gravity Probe B backs general relativity
16 April 2007

A preliminary analysis of data from the Gravity Probe B satellite has confirmed that the Earth's mass distorts the fabric of space and time…

…Gravity Probe B used superconducting quantum interference devices (SQUIDs) to measure tiny changes in the orientations of four perfectly-spherical, quartz gyroscopes… physicsweb.org
 

M. Uijt de Haag, D. Venable, M. Schmearcheck, Ohio University…                   ...Paper presented at the ION 2007.
 

Mitsubishi Electric is develo-ping a new space-based communications infrastruc-ture to be implemented in 2009. It’s called the Personal Navi, and it’s a new multimedia service for mobile phones that can deliver moving images. It uses the japanese Quazi-Zenith satellite system:
global.mitsubishielectric.com

 

SEISMIC NEWS:

• Fugro contracted for 3D shoot off India (may 2007)

• Bolivia's Congress approves 44 new oil and gas contracts

• Lybia annouces $900m gas deal with BP

• Chile will offer 10 Magallanes Basin blocks in June  

• OMV modernizes Austria's oil and gas production

• Seismic firms see business rise with search for oil and gas 15-04-07: gasandoil.com

• See our own Seismic Crew Locator on our web site. If you want us to provide a more accurate position for your crew, please contact us…
www.zupt.com
 

IN THIS ISSUE:
• News
• The Backpack today
• Suggestions
• Inertial & other survey tips
• Seismic info
• The rest of the World
 

ZEST - A monthly newsletter providing information, tips, insights and commentaries on the use of Zupt inertial navigation systems, other inertial systems, and their software, bug tracking, navigation in general, seismic survey, the use of GP Seismic™, and internet links etc

 To subscribe, email us at:              
   jg@zupt.com     

SURVEY INFO:

Actual (real-world) accuracy of RTK GPS.

• << …The use of an RTK capable GPS system can compensate for atmospheric delay, orbital errors and other variables in GPS geometry, increasing positioning accuracy up to within a centimeter…>> …actual –common- quote from a GPS manufacturer’s web site…

• Misconceptions on the actual accuracy of a set of data collected in the real world using the GPS RTK method are quite common and are due to overly optimistic statements from manufacturers, backed up by carefully conducted studies done by engineers and academics in well controlled environments (in wide open area etc…).

• Unfortunately the common surveyor doesn’t choose the environment of his project and tries to “push” his instrument to its limits: close to these buildings, under those trees (I am getting a signal!), with a hard hat close by the antenna etc…

• In most cases the only CHECKS, are the “QC” values generated internally by the receivers. Few have the luxury of resurveying a sample of their survey points with a different method, or comparing them to a reference datum.

• In fact in most average situations, a certain number of errors and blunders will introduce some significant biases into the results of a GPS RTK survey conducted in mixed vegetation areas (even with all internal “masks” set to the most rigorous levels).

• Here are the results of a comparison study done between the vertical values of about 2000 GPS RTK points surveyed with strict criteria (masks), in a mixed pasture-forest area, and the ground-truthed Lidar survey of the same project:

RTK Data:

Mean difference= -0.16 ft= -0.05m

Standard deviation= 1.05 ft= 0.32m

97.14% of the points are within 3 ft (0.91m) of Lidar DTM.

99.18% of the points are within 5 ft (1.51m) of Lidar DTM.
 

Actual (real-world) accuracy of Inertial Survey.

• on the same project about 8000 points were surveyed with INS.

• Here are the results of the same comparison study done between the vertical values of those INS points , in the same mixed pasture-forest area, and the ground-truthed Lidar survey of the project:

INS Data:

Mean difference= -0.18 ft= -0.05m

Standard deviation= 1.45 ft= 0.44m

94.36% of the points are within 3 ft (0.91m) of Lidar DTM.

99.18% of the points are within 5 ft (1.51m) of Lidar DTM (same as RTK).

THE READERS OF THIS NEWSLETTER…

We have close to eight thousands readers of this newsletter from all over the world… by just looking at your email address and its country code top level domain (cctld) name you are:

4206 ".com" (please tell us your country name)

332 ".edu"

290 ".net"

244  ".ca" (how is the weather up there ?)

222  ".mil" (we salute you)

165  ".gov"

145  ".fr" (bonjour!) and hundreds from all countries from the Americas, Europe, Africa and major Asian and Pacific nations.

SUGGESTIONS FOR IMPROVEMENT of B-PINS:

• Upgrade to the latest version of GPSeismic™ and interface directly with QuikLoad for the creation of Zupt zgw precomputed files and QuikView for the processing of zgs survey files. ( www.gpseismic.com ).... by the way v.2007 is out.

• Glenn Drummond of Global Geophysical recommends to eliminate the confirm screen when you call Next or Previous points on the Steer screen.

• Test the beta version of our Inline/Lateral Offset screens… Ask for our latest v2.0 Zing™ software.

• Shoulder Straps are a bit too wide says Dustin of GLS LLC (David Burns)… Dustin has strong shoulders. Also: "… can you build coordinates (of an offset point)?"… we should add a “Goto” function in the Inline/Lateral Offsets screens.

• In Case of Emergency, if the touch-screen stops working… you need to have access to the menus by using the keypad only (Dean Kniech of PGS onshore).

• Procedure to avoid errors in instrument height (HI). Always survey the points (Record) with the pack on the back, and always put the pack on the ground for a Tie (Update). That way the HI will never change for a given operator. The reason is that the height of the pack above ground (HI) doesn't change for a given operator, as long as he keeps the pack on his back during the survey...

• Geodetic Azimuth vs Grid Azimuth. Since your B-PINS instrument works on the WGS84 ellipsoid, make clear to the operators that all Azimuths used are Geodetic Azimuths and not grid azimuth like for the theodolite surveyor -maybe on the same project- who is working on the projection. The difference can be several degrees (it is the meridian convergence or “map angle”), and at large offset distances can translate into significant errors when not handled properly.



SEISMIC INFO…

• Who am I surveying for? Before heading for the field, the INS survey operator must ask himself what kind of line or grid he will survey, who will work on it later, and what are the reasons for the layout specifications. In geophysical survey for example, there are two types of survey lines: “receiver lines” where the geophones will be laid out and “sources lines” where the energy source points will be drilled or vibrated.

• Because of the great flexibility of inertial survey, the operator can decide to draw very straight lines, or to wind around obstacles at will… In no instance is there a need to remove or displace vegetation or property for the sake of the survey alone, which is not the case for other survey methods requiring line of sight or other (optical).

• Receiver Lines. What type of geophone will be used? -do they need to be oriented?- And in what pattern: straight line, circle, other? If numerous geophones need to be placed in a straight line, make sure you cut that wide and direct line between stakes, but if they are laid out in circles at each stakes and there is enough slack in the cables, you might be allowed some winding between trees and bushes…

• Source Lines. Place the stake in a spot where the driller will drill it, which often means to offset it 20 to 30 feet or more from the pre-plot position to an opening or an area of flatter ground. Does a point need to be placed a few feet on the other side of a fence or a stream? What is its access route? Are there branches overhead, or electric lines? Surveying the point where it will actually be drilled makes for more accurate data… not less… The same goes for vibrated points: they need to stay on the smoothed path of the vibrators, not in corners and dead ends, where the machines will not go anyways… Oh and let’s survey the center of the path (pad location), not the edge of it…


• Even in countries where manpower costs seem lower, the requirement to respect the existing environment is well indicated in seismic contracts. Plants and animals must be protected. This type of “low impact” seismic can be achieved with inertial survey systems that do not require any vegetation cutting in sensitive areas…

Seismic in the “morichal” .South America.



 

Save money, save the environment, be safe…

Here are those who are too few and need to distribute this letter throughout their beautiful nation:

Bangladesh (.bd), Bolivia (.bo), Botswana (.bw), Costa Rica (.cr), Cuba (.cu), Cyprus (.cy), Iceland (.is), Jamaica (.jm), Kuwait (.kw), Kazakhstan (.kz), Lebanon (.lb), Sri Lanka (.lk), Lesotho (.ls), Latvia (.lv), Luxemburg (.lu), Monaco (.mc), Malta (.mt), Nigeria (.ng), Papua New Guinea (.pg), Seychelles (.sc), Syria (.sy), Zambia (.zm), Zimbabwe (.zw)... oh and mr ".tv" are you really from Tuvalu?

Last word
You can find our previous newsletter on our web site. Please let us know what you would like to see in a newsletter. Send us info, tips, suggestions, links, pictures etc… let us know if you want your questions or comments to remain private or to appear in the newsletter. Circulate it around, and /or give us email addresses of others who would like to receive it.

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Find our link “Feedback” under Contacts on our web site. Please use it to send us any info, not only on bugs in our software, but suggestions etc…

www.zupt.com/feedback

See you soon!
 

YOUR LETTERS…

[Great Newsletter] These are a nice touch and a good source of information. They depict the level of professionalism that the company strives for. I’m surprised that you have time considering how busy you are. Great job guys! Les Merriam.

Just a quick message to say what a fantastic map you have created. It will be a great resource for us in the industry. I've been wanting to do this for so long but never got around to it (or didn’t have the tools).
I have mailed the link to my consultancy [] who are now the largest consultancy for client reps on seismic vessels so I hope they will distribute the link so as they can give you regular updates on crew / vessel locations and to leave comments on future work. Again, well done on the great site. Aled…communitywalk.com/map/89151



…In the newsletter you run an item on "Source Point Offsets". To me, as a person with some knowledge of seismic survey design it is disappointing to see that some companies still use inferior rules for offsetting shots. To you, as a provider of surveying equipment, it is just a client's wish. Yet, it may help if you understand why offsetting of shots in the described way is not the way to do things.



The reason why many seismic specialists still use the offsetting and skidding technique stems from the old days when seismic data were gathered into bins, stacked and then poststack migrated. At those times it was important to avoid midpoint smear in the bins and the offsetting rules are designed to get all midpoints as close as possible to bin centers. However, as soon as there is some dip, at least DMO is applied prior to stacking and already then midpoint centering is of no use any more, as DMO is applied to individual traces and you can tell the program to output at bin centers. More importantly, nowadays, prestack migration techniques are becoming more and more important, because these techniques honor the true position of sources and receivers and the true raypaths. In prestack migration all traces are modified and output to a square grid of output positions around the input location. So, midpoint centering is not at all important anymore. What is really important is to promote optimal prestack imaging results.

The way to achieve optimal imaging results is to ensure that an M-fold data set can be split into M single-fold gathers, each of which is optimally suited for creating an image. Then you get M different images at each output point and these M images can be stacked for optimal noise suppression. (It should not surprise you that single-fold data can be used for imaging: that is exactly what we do when applying poststack migration; the input to poststack migration also consists of one trace per bin, i.e., is single fold.) The task of survey design is to come up with rules that promote optimal imaging capability of the M single-fold subsets. The best way to do this is by considering sources and receivers as samples of their respective acquisition lines. If you cannot lay out straight acquisition lines, then you should attempt to lay out smoothly curved acquisition lines. Prestack images always involve the use of many neighboring traces with neighboring receivers from a receiver line and neighboring sources from a source line. This means that sources should never be treated as individual entities. Solitary shots as produced in the offsetting and skidding approach cannot produce good prestack images and if you have many of such unrelated shots one can just as well use poststack migration, because there will be too many spatial discontinuities in the data set for successful prestack imaging.



Another way of looking at this is by realizing that sources in the crossline direction have the same role as receivers in the inline direction. Usually common shot gathers look perfect, because receiver stations are usually laid out along straight lines. Common receiver gathers should look like common shot gathers, and that can only happen if the shots are arranged in a regular pattern as well. Solitary shots produce awfully looking receiver gathers. They produce lots of migration artifacts due to the spatial discontinuities in those gathers.



Acquisition is the most expensive part in the chain of acquisition, processing and interpretation. It is a shame to see so much money wasted due to inferior rules for dealing with obstructions. Maybe you can help your clients to do better than what they are asking for. Best regards, Gijs Vermeer.



Find our link “Feedback” under Contacts on our web site. Please use it to send us any info, not only on bugs in our software, but suggestions etc…

www.zupt.com/feedback