Wednesday 30 December 2009

Comparison of measurements in co-ordinate metrology

Abstract

The primary output from a co-ordinate metrology system is a set of measured co-ordinates representing the locations of targets. This paper is concerned with the following issues: (a) how do we express the uncertainty associated with a set of measured co-ordinates and how can we summarise the uncertainty characteristics of a co-ordinate measuring system, (b) if two co-ordinate measuring systems measure the same set of targets, how do we assess whether the two sets of measured co-ordinates are consistent with each other, and (c) given two sets of measurements of the same set of targets, how can we obtain a combined estimate of the target locations. Any concept of traceability of co-ordinate measurements will need to provide a way of answering these questions. We show that multivariate probabilistic techniques, multivariate counterparts to those described in the Guide to the Expression of Uncertainty in Measurement, can give useful answers to these questions. We illustrate their application to laser tracker and theodolite systems.

Keywords: Co-ordinate metrology; Uncertainty; Traceability

link


Ramsden's three foot geodetic theodolite, 1792.



This theodolite is the oldest surviving of its size and was used on the Principal Triangulation of Great Britain and Ireland from 1792 to the early 19th century. It was used to measure both vertical and horizontal angles to a high degree of accuracy. This helped to produce the network of reference points underpinning the Ordnance Survey maps of the United Kingdom.

Image number: 10280157


Saturday 26 December 2009

Theodolite has ranked as the top selling navigation app in the US and UK

Hunter Research and Technology is pleased to announce that its new iPhone app Theodolite has ranked as the top selling navigation app in the US and UK iTunes stores after just three weeks on the market. This novel multi-function augmented reality app serves as a compass, GPS, map, zoom camera, and two-axis inclinometer. Theodolite overlays real-time information about position, altitude, bearing, and horizontal/vertical inclination on the iPhone’s live camera image.

Williamsburg Virginia, USA – Hunter Research and Technology is pleased to announce that its new iPhone app Theodolite has ranked as the top selling navigation app in the US and UK iTunes stores (sales data for December 19-20) after just three weeks on the market. This novel multi-function augmented reality app for the iPhone serves as a compass, GPS, map, zoom camera, and two-axisinclinometer . In addition to holding the top sales spot in navigation, Theodolite has been featured by Apple in the New and Noteworthy category, and has broken into the Top 50 Paid Apps ranking in the US and Top 20 in the UK. Weekly worldwide sales of Theodolite exceeded 10,000 units for the week ending December 19.

Based on the concept of a centuries-old astronomical instrument, Theodolite overlays real-time information about position, altitude, bearing, and horizontal/vertical inclination on the iPhone’s live camera image, turning the iPhone into a sophisticated location-aware viewfinder. Uses are endless, from land surveying to basic navigation, and the app is great for hiking, boating, sightseeing, photography, and sports.

Theodolite lets users take camera images directly from the app, with 2X and 4X digital zoom options. Geographical data can be stamped on the saved image for later reference. Current position can be viewed on the built-in map, with standard, satellite, and hybrid modes. On an iPhone 3GS, bearing is updated live on the map with both fixed view and world rotation.

Pricing and Availability:
Theodolite 1.0 runs on any generation iPhone with OS 3.1 or later and is available for $0.99 (USD) on the iTunes App Store. GPS functionality requires an iPhone 3G or 3GS. Compass functionality requires an iPhone 3GS. More information, including screenshots, is available on the Hunter Research and Technology website. Media professionals interested in reviewing Theodolite can request a promotional code to download the app from iTunes at no cost.

Wednesday 23 December 2009

Bausch & Lomb 1908 catalog of Engineering Instruments


7 inch Complete Transit Theodolite

This instrument has been used on important work as, for example, by the Canadian and United States governments in boundary surveys. It is well adapted for time and latitude observation, as well as triangulation and general survey work. We have supplied them to nearly all the leading colleges of this country. as it is particularly well adapted for purposes of instruction.

The U-shaped standards are employed in construction, great strength resulting from their being cast in one piece. The graduations of the horizontal circle are on a beveled edge, and read to 30" by two opposite verniers, the circle being divided into 1/3 degree. Attached reading glasses are provided for both the horizontal and the vertical circles if desired. The vertical circle is 5 1/2" in diameter and reads to 30" by double opposite verniers. Both the circle and the verniers are fully protected by covering guards. The telescope is inverting. The extra long center is of steel, resting in a cast-iron bearing, giving strength, durability and smoothness of motion, thus permitting extra sensitive levels.

Other Specifications

The horizontal circle has a diameter of 7" inside of the graduations, and 8 1/8" outside. The graduations are in 1/3 degrees, and read to 30" by double opposite verniers. The vertical circle has a diameter of 4 1/2" inside the graduations, and 5 1/2" outside. This circle also reads to 30" by double opposite vemiers.

The erecting telescope is 13" in length, with a power of 22 and 35 diameters. The effective aperture is 1 1/2" and the apparent field 36 degrees.

The telescope level is 4 3/4" long, and each division is sensitive to 10" of arc. The graduations are 2 mm. apart. The standard levels are also graduated in 2 mm. divisions, each division having a value of 30" of arc, The striding level to the telescope axis is graduated like the others, and each division represents 10" of arc.

The range of shifting center is 1/2". Three (not four) German silver leveling screws are provided.

The instrument is 14 1/2" in height, and weighs approximately 20 lbs., in carrying case 35 lbs., and 70 lbs. packed for shipment. The split-leg tripod weighs approximately 8 3/4 lbs., and when packed for shipment 21 lbs. The extension tripod weighs about 10 lbs., or 22 1/4 lbs. when packed for shipment.

Friday 18 December 2009

DGT02 - 2 sec Digital Theodolite

2-second digital theodolite totally re-designed for 2002, with a number of features you have come to expect from CST/berger.

  • State of the art glass encoder
  • 2-second horizontal and vertical readout.
  • Precision dual LCD panels with large, easy-to-read numbers
  • Vertical Tilt Sensor monitors the tilt angle in x-axis
  • Vertical angle measuring; provides three different options plus percentage of grade
  • Auto Power-Off Option: if unit is not moved it will shut off in- 20 minutes, 30 minutes or infinity.
  • Optical plummet
  • Zero resetting
  • Water resistant, sealed construction
  • Removable tribrach for multiple set-ups
  • Built-in battery pack can be attached and deteched by a single action
  • One year warranty

Wednesday 16 December 2009

Total Station (EDM)

A total station is an electronic/optical instrument used in modern surveying. It is also used by archaeologists to record excavations as well as by police, crime scene investigators, private accident reconstructionists and insurance companies to take measurements of scenes. The total station is an electronic theodolite (transit) integrated with an electronic distance meter (EDM) to read distances from the instrument to a particular point. Some models include internal electronic data storage to record distance, horizontal angle, and vertical angle measured, while other models are equipped to write these measurements to an external data collector, which is a hand-held computer.

Angles and distances are measured from the total station to points under survey, and the coordinates (X, Y, and Z or northing, easting and elevation) of surveyed points relative to the total station position are calculated using trigonometry and triangulation.

Data can be downloaded from the total station to a computer and application software used to compute results and generate a map of the surveyed area.

Some total stations also have a GNSS interface which combines the advantages of these two technologies (GNSS - line of sight not required between measured points; Total Station - high precision measurement especially in the vertical axis compared with GNSS) and reduce the consequences of each technology's disadvantages (GNSS - poor accuracy in the vertical axis and lower accuracy without long occupation periods; Total Station - requires line of sight observations and must be set up over a known point or with line of sight to 2 or more points with known location).

Most modern total station instruments measure angles by means of electro-optical scanning of extremely precise digital bar-codes etched on rotating glass cylinders or discs within the instrument. The best quality total stations are capable of measuring angles to 0.5 arc-second. Inexpensive "construction grade" total stations can generally measure angles to 5 or 10 arc-seconds.

Measurement of distance is accomplished with a modulated microwave or infrared carrier signal, generated by a small solid-state emitter within the instrument's optical path, and refected by a prism reflector or the object under survey. The modulation pattern in the returning signal is read and interpreted by the computer in the total station. The distance is determined by emitting and receiving multiple frequencies, and determining the integer number of wavelengths to the target for each frequency. Most total stations use purpose-built glass Porro prism reflectors for the EDM signal. A typical total station can measure distances with an accuracy of about 1.5 millimetres (0.0049 ft) + 2 parts per million over a distance of up to 1,500 metres (4,900 ft).[1]

Reflectorless total stations can measure distances to any object that is reasonably light in color, to a few hundred meters.

Robotic total stations allow the operator to control the instrument from a distance via remote control. This eliminates the need for an assistant staff member as the operator holds the reflector and controls the total station from the observed point.

Monday 14 December 2009

Leica TM5100A

The Industry Standard
The Leica TM5100A Industrial Theodolites bring precision on-site. With unrivalled precision and superb optics, our theodolites have become the standard instrument of choice in the aerospace industry for satellite alignment as well as for system and Heads Up Display alignment for combat aircraft.

Modular Flexibility
No matter your requirements, no matter the task at hand, we have the instrument that get your job done. When setting out, a single-instrument system, configured to your specifications, will meet most demands. And when the need arises, the system can be expanded to a multi-instrument system.

* Proven track record with several thousand TPS5000 instruments on the market give you the highest reliability possible.
* Highest angle accuracy make Leica Geosystems Indusrial Theodolites the most precise instruments worldwide in their category.
* Completely open and programmable software interface seamlessly integrates with your standard software or with automated processes via serial communication.
* Motorization & Automation features offer completely guided and highly automated measurement of inspection and assembly processes.
* Minimal setup time within just a few minutes guarantee minimal downtime in production and assembly processes.
* Wide range of accessories and targets give you the best adaptation to your part inspection, building and tooling applications.
* Use your instrument under almost all conditions – both indoors and outdoors.
* Built-In Autocollimation Eyepiece – a recognized global standard tool for direction and coordinate-based precision alignment tasks.

The inspection package Spatial Analyzer from New River Kinematics provides a perfect solution for multiple Theodolite Systems from Leica Geosystems. The powerful Unified Spatial Metrology Network (USMN) together with a wide range of analysis functions allows to solve even the most demanding measurement tasks.

Saturday 12 December 2009

Which is better Theodolite or Total Station?

Hello fellow professionals and others in similar field of interest.The question whether a theodolite is better than a total station is to the best of my knowledge answered this way.However each have their advantages as well as disadvantages from one another.It all depends on what factor is considered here at the moment.The advantages and disadvantages are however drawn from the factors as I go to highlight them as follows:
Factor1.The theodolite would be better if the cost of hiring the equipment is considered,therefore I call this the economic factor.Hence it would be by far cheaper for you to hire and use a theodolite.But you must bear in mind that if you have not used a theodolite before,then you run the risk of having some technical problems,not only that you would have to make a few mathematical deduction that is called a survey computation for you to have your bearings and distances well in place.It might be rigorous because distances have to be measured with a linear tape(steel tape).
Factor2.This has to do with personnel.You would have to need some few hands,depending on the scale or scope of the job at hand.Therefore,you have to bear in mind the cost of hiring laboures.
Using the Total Station would be by far the best,because it is easy to use and the instances of having to measure distances has to be eliminated.Then your distances are digitally deduced and the accuracy is more precise than having to use manually a linear steel tape.
You don´t need any rigorous mathematical numerical and angular deduction since there would not be any need to under go a rigorous survey computation.
Data acquired are just have to be downloaded and with some special software the data are processed and your desired result in most cases,your map or plan is ready for print.
As you have not used a theodolite before or bearing in mind you don´t have the required professional skill to use it,better for you to use a total station.That is easier for you to operate.But it is very costly.
I hope I have answered this question to satisfaction.I apologise where any form of professional bluders or totology may arise,knowing full well no one is really perfect.It has been a long time I have not touched anything that has to do with this topic.Thank you very much.

Friday 11 December 2009

Underground Surveying.

A primer in coal mine surveying and mapping.

When someone learns that I survey in underground mines, they very often ask, "What's it like to survey underground?" This article will discuss the similarities and differences between surveying in the sunlight and surveying deep underground.

In Alabama, where my coal mining experience has been, the seams are fairly level and range in thickness from around 2' to as much as 15'. If the coal seam or strata is thick enough to stand on, it is usually called high coal; if not, it is called low coal. In the low coal mines, coal is moved by low profile conveyor belts. In transportation areas, the roof is blasted higher than the seam, and at conveyor belt headers and other key locations, rock is removed to provide room to stand and work. The ideal height of a coal seam is around 7', which permits walking upright while being able to reach the roof. Anything much less or much more presents problems for the workers.

One of the first differences a new surveyor underground notices is the fact that all the survey points are overhead. Because of the mud and the constant traffic of mining equipment, it is not practical to set points in the bottom of the seam. Surveys are generally run on the centerline of the mine areas. Points are set by first drilling a small hole in the roof about 3/4" deep, into which a round wooden plug is driven. Then the survey point is marked by driving a metal spad into the plug. A spad looks like a small flat key. It has a round head with a hole through it and a straight shaft with a rounded point. Once the spad has been put on line, a plumb bob cord is threaded through the spad and tied with a slip knot. Distance measurements are made to the cord with a surveyor's chain or with an EDM. If electronic measurements are made, the prism must be mounted on a special holder to hang it from the spad. In high coal, a 32-ounce bob is used, since the high volume of air moving to the working faces makes it di fficult to steady a lighter one. In low coal it is sometimes necessary to use an extremely short bob, since there is so little headroom.

A Survey Day in the Mines

Surveyors are used to carrying a lot of stuff. To do their work efficiently they need plumb bobs, prisms and plumbing poles, measuring tapes, paint, flagging, nails, tacks, stakes, hammers, field books, calculators and data collectors, transit, EDM, tripod, radios... Underground mine surveyors need most of the same stuff, but that is only the beginning. Every surveyor underground wears a miner's hardhat and a wide leather belt that holds a self-rescuer to supply oxygen in case of emergency, plus a heavy battery connected by a cable to an electric lamp on the hardhat. Each crew carries a hand brace and drill bits as well as a heavy-duty, battery-powered hand drill. Instead of stakes and hubs, they carry wooden plugs and spads. They also carry a methane detector to avoid setting off an explosion. Since parts of most coal mines are wet, everyone wears 16"-high rubber safety boots. In thin coal seams the miners and surveyors must work on their knees in the mud, so heavy duty knee pads are standard equipment. In h igh seams the crew must carry a tall step ladder to reach the roof.

Another difference in underground surveys is that there often must be very short sights. In vertical shafts, it is often necessary to have two control points less than 20' apart since the points are transferred down the vertical shaft by wires or optical devices. And mine entries are often driven around 50' apart. Instrument setups are done with utmost care. The transit is leveled under the plumb bob (there is a mark on the top of the instrument), then the scope set on a 90 degree zenith angle. Then the position under the bob is checked again to ensure that there is no eccentricity. The string is hung from the hole through the spad, making sure it is tied so as to hang from the lowest point in the hole.


Wednesday 9 December 2009

Surveying Instructions with NBMG's EDM Theodolite

Setting Up an Instrument Station

  1. Place tripod over marker. Loosen the leg adjustments, lengthen the legs so plate is almost at eye level, then tighten again. Center tripod over marker using plumb bob. Push legs into ground with tabs near bottom, adjusting so plate is approximately level.

  2. After tripod is set in ground try not to touch or bump legs. Do not lean on tripod.

  3. Loosen tripod plate mounting screw and remove plastic plate cover. Use tabs on it to hang it on the tripod.

  4. Open theodolite case. Lift theodolite by top (battery) handle only, never by telescope barrel. Wipe dust from plate and theodolite base. Place theodolite on tripod plate.

  5. Engage mounting screw in theodolite base. Check optical plummet and slide theodolite gently on plate to center over marker. Then tighten the mounting screw securely.

  6. Loosen the azimuth and vertical angle controls. Level the theodolite by first adjusting the knurled leveling screw wheels so bull's-eye level is centered. Then rotate azimuth so horizontal level spans between two leveling screws. Turn the screws in opposite directions; the bubble will move in the direction of the left screw. Turn instrument 90 degrees and level by adjusting the third screw only. Repeat this procedure once for each pair of screws. Rotate instrument to check levels.

  7. Place prism target on rod and tighten locking ring. Extend rod so prism center is within 1 cm of theodolite objective height, with rod end resting on ground and in vertical orientation (check bull's-eye level on rod). Tighten knurled brass locking sleeve on rod. Measure prism and rod heights.

  8. Sight true north with brunton compass. Remember to set local declination. Identify landmark on horizon in north direction. Send rodman out 30 m in that direction. Sight rod with brunton and wave rodman to north position.

  9. Remove theodolite objective lens cap and replace with sun shade. Turn theodolite to sight on rod. Lock azimuth control. Turn instrument on with switch on battery handle. Wait 1 minute, then resight on rod using fine upper azimuth adjustments. Theodolite LCD panel should read some angle. Press 0-Set button to set north azimuth. Do not disturb lower azimuth lock.

Measuring a Station

  1. Rodman and surveyor each have a radio. Keep power setting on low and channel at 3. Avoid draining the batteries with unnecessary conversation.

  2. Rodman walks to station, announces the station number (written on flag) to surveyor by radio, and removes prism cap. The rodman holds rod vertically (continuously checking rod level) with prism pointing at theodolite. The rodman must remain still in this position until waved off or radioed by the surveyor.

  3. When waved off, rodman replaces cap on prism and walks to next station. Upon reaching the station the rodman should automatically set the rod in position for measurement and radio the station number.

  4. At the theodolite, the surveyor sights on the prism, first with the sight atop the telescope, then through the telescope. The outer eyepiece ring sets telescope focus; the innermost ring focuses the crosshairs. Note the station number reported by the rodman and check for consistency as measurements progress.

  5. If battery voltage is adequate, surveyor locks the angle controls and uses the fine adjustments to position the crosshairs on the prism. Note the horizontal and vertical angles, using the V/H button to switch the display between the two. Read the angles to the recorder, taking care to notice any minuses at the left side of the display.

  6. Begin laser ranging by pressing the triangle button. The instrument beeps periodically when the laser is on, consuming much power. After the instrument establishes the distance, press the triangle button to read the slope distance, horizontal distance, and vertical distance. Note any minuses.

  7. Press the NEZ button to read delta-y (northing), delta-x (easting), and delta-z (elevation change), record with any minuses.

  8. Halt laser ranging and conserve battery power by pressing the V/H button as soon as possible.

  9. Wave off or radio the rodman to continue to the next station.

  10. Check the theodolite leveling and carefully adjust if necessary, while rodman walks to next station.

Taking Down an Instrument Station

  1. To put away theodolite, turn power off and unlock azimuth and vertical angles. Replace sunshade with objective cap.

  2. Hold theodolite by battery handle. Loosen mounting screw and lift theodolite from tripod. Rotate base so white marks line up. Place theodolite in case with objective and lower angle lock down. Close case and latch.

  3. Replace tripod plate cover and tighten mounting screw. Lift tripod, bring legs together, and loosen leg adjustments. Shorten legs and retighten. Bind legs with strap.

  4. Put surveyor's notes in safe place. Remove prism from rod and put in padded case. Turn off radios.

  5. Charge both battery handles and both radios each night.

Sunday 6 December 2009

A surveying device that works with surveying prisms mounted on the masonry and measures any horizontal or vertical movement in the walls

A year after the MBTA suspended a construction project that caused a crack from the foundation to the roofline of Old South Church, the jackhammers are back in operation, thudding away and sending small tremors through the 136-year-old National Historic Landmark across from Copley Square.

Despite the clamor that echoes through the ornate sanctuary, MBTA and United Church of Christ congregation officials said the hallowed building is structurally sound.

Working with a team of structural engineers, restoration architects, stained-glass consultants, and an organ conservator, the contractor has installed an array of sophisticated subsurface devices to monitor the soil and the foundation to ensure there is no further damage to the church’s distinctive Roxbury puddingstone façade, its signature Gothic campanile, or its 6,500-pipe organ.

“We’re satisfied that they’re being extremely careful and that the foundation is not in jeopardy,’’ said Lois Corman, who is monitoring the construction for Old South Church.

The $45 million construction project, which is expected to take another year, was suspended last December during excavation work by an MBTA contractor hired to make the Copley Square subway station accessible to the handicapped. Framingham-based J.F. White Contracting Co. is installing an elevator shaft and replacing the station’s old brick entrance on Dartmouth Street.

MBTA officials said the work is monitored 24 hours a day by automated instruments in the ground and on the church’s walls that provide “real-time’’ data to reflect any shifts in the building or defects in the foundation.

“The automated instruments allow the project to monitor the building nearly continuously [several times an hour] in real time, and the data are uploaded to a project office site so that key parties can track the response of the building to construction activities,’’ said Lydia Rivera, a spokeswoman for the MBTA.

She said the equipment enables “rapid reaction to correct or mitigate undesirable impacts to the building.’’

The equipment includes a theodolite, a surveying device that works with surveying prisms mounted on the masonry and measures any horizontal or vertical movement in the walls. There also are seismographs to monitor vibrations from the construction and automated meters that track ground movement, groundwater changes, and any opening or closing movement in the large crack on the wall facing Dartmouth Street, which will be repaired after the elevator shaft is fully excavated and backfilled.

Neither MBTA nor church officials know how much it will cost to repair the damage, which they said will be covered by J.F. White’s insurance company. They expect the crack, still visible inside and outside the church, will be repaired by the end of next summer.

Reverend Nancy S. Taylor, the senior minister at the church, said she is comfortable with the new safety measures.

“We have investigated the current condition of the wall, foundation, and timber piles, and the MBTA and its contractor have redesigned the current and future construction activities with the purpose of ensuring no further damage to the church,’’ she said.

The project is complicated because the area around the church is built on fill and all the buildings are supported by wooden pilings, making them vulnerable to damage from excavation and drilling. The contractor also has to deal with the concerns of neighbors, some of whom filed an unsuccessful lawsuit against the MBTA because of aesthetic concerns about the project.

The Old South congregation traces its history back more than three centuries, to 1669, when it was established as Third Church in Boston.

It was later renamed Old South Church and moved from downtown to its current location in the Back Bay in 1875.

The building, an example of Ruskinian Gothic architecture, was designed by Charles Amos Cummings in the 1870s and updated by the Tiffany firm in 1905. It was renovated in the mid-1980s by Shepley Bulfinch Richardson and Abbott.

With Jersey barriers blocking off much of the corner of Dartmouth and Boylston streets, large earth-moving equipment and jackhammers have filled the area with piles of rubble.

While church officials have to schedule musical events and other meetings around the construction, they said they’re happy to see work underway again.

“Old South is as eager to see the newly renovated and accessible Copley T Station as we are eager to ensure that our building is not damaged any further in the process,’’ Taylor said. “We believe that with good will and good care, these two things are not incompatible.’’

A surveying device that works with surveying prisms mounted on the masonry and measures any horizontal or vertical movement in the walls

A year after the MBTA suspended a construction project that caused a crack from the foundation to the roofline of Old South Church, the jackhammers are back in operation, thudding away and sending small tremors through the 136-year-old National Historic Landmark across from Copley Square.

Despite the clamor that echoes through the ornate sanctuary, MBTA and United Church of Christ congregation officials said the hallowed building is structurally sound.

Working with a team of structural engineers, restoration architects, stained-glass consultants, and an organ conservator, the contractor has installed an array of sophisticated subsurface devices to monitor the soil and the foundation to ensure there is no further damage to the church’s distinctive Roxbury puddingstone façade, its signature Gothic campanile, or its 6,500-pipe organ.

“We’re satisfied that they’re being extremely careful and that the foundation is not in jeopardy,’’ said Lois Corman, who is monitoring the construction for Old South Church.

The $45 million construction project, which is expected to take another year, was suspended last December during excavation work by an MBTA contractor hired to make the Copley Square subway station accessible to the handicapped. Framingham-based J.F. White Contracting Co. is installing an elevator shaft and replacing the station’s old brick entrance on Dartmouth Street.

MBTA officials said the work is monitored 24 hours a day by automated instruments in the ground and on the church’s walls that provide “real-time’’ data to reflect any shifts in the building or defects in the foundation.

“The automated instruments allow the project to monitor the building nearly continuously [several times an hour] in real time, and the data are uploaded to a project office site so that key parties can track the response of the building to construction activities,’’ said Lydia Rivera, a spokeswoman for the MBTA.

She said the equipment enables “rapid reaction to correct or mitigate undesirable impacts to the building.’’

The equipment includes a theodolite, a surveying device that works with surveying prisms mounted on the masonry and measures any horizontal or vertical movement in the walls. There also are seismographs to monitor vibrations from the construction and automated meters that track ground movement, groundwater changes, and any opening or closing movement in the large crack on the wall facing Dartmouth Street, which will be repaired after the elevator shaft is fully excavated and backfilled.

Neither MBTA nor church officials know how much it will cost to repair the damage, which they said will be covered by J.F. White’s insurance company. They expect the crack, still visible inside and outside the church, will be repaired by the end of next summer.

Reverend Nancy S. Taylor, the senior minister at the church, said she is comfortable with the new safety measures.

“We have investigated the current condition of the wall, foundation, and timber piles, and the MBTA and its contractor have redesigned the current and future construction activities with the purpose of ensuring no further damage to the church,’’ she said.

The project is complicated because the area around the church is built on fill and all the buildings are supported by wooden pilings, making them vulnerable to damage from excavation and drilling. The contractor also has to deal with the concerns of neighbors, some of whom filed an unsuccessful lawsuit against the MBTA because of aesthetic concerns about the project.

The Old South congregation traces its history back more than three centuries, to 1669, when it was established as Third Church in Boston.

It was later renamed Old South Church and moved from downtown to its current location in the Back Bay in 1875.

The building, an example of Ruskinian Gothic architecture, was designed by Charles Amos Cummings in the 1870s and updated by the Tiffany firm in 1905. It was renovated in the mid-1980s by Shepley Bulfinch Richardson and Abbott.

With Jersey barriers blocking off much of the corner of Dartmouth and Boylston streets, large earth-moving equipment and jackhammers have filled the area with piles of rubble.

While church officials have to schedule musical events and other meetings around the construction, they said they’re happy to see work underway again.

“Old South is as eager to see the newly renovated and accessible Copley T Station as we are eager to ensure that our building is not damaged any further in the process,’’ Taylor said. “We believe that with good will and good care, these two things are not incompatible.’’

Sunday 29 November 2009

Digital Theodolit Sokkia

Digital Theodolite
Sokkia DT-210

- Pembacaan : 1 "
- Ketelitian : 2 "
- Pembesaran Lensa : 30x
- Display : 2 Muka

Digital Theodolite
Sokkia DT-510

- Pembacaan : 5 "
- Ketelitian : 5 "
- Pembesaran Lensa : 30x
- Display : 2 Muka

Digital Theodolite
Sokkia DT-510A

- Pembacaan : 5 "
- Ketelitian : 7 "
- Pembesaran Lensa : 30x
- Display : 1 Muka

Digital Theodolite
Sokkia DT-610

- Pembacaan : 5 "
- Ketelitian : 7 "
- Pembesaran Lensa : 26x
- Display : 1 Muka

Friday 27 November 2009

During the 2009 visit of the SA Agulhas, Jürgen Matzka from Denmark, Alan Berarducci from the US and Bjorn Ove Husoy from Norway visited Tristan to finalize the magnetometer station on Tristan da Cunha.

The station was started in 2008 by Leo Gening from Enviroconsult and now, in its final setup, measures the magnetic field of the Earth every second. To deliver data according to the highest standards, Robin Repetto (who is also station manager) and Jason Green were trained to perform weekly calibration measurements with a theodolite. The other two instruments of the station are a Danish FGE magnetometer, located in a pyramide shaped shelter and sending online data to the oiutside world, as well as a Candian GSM magnetometer that measures the magnetic field strength. The project is a cooperation of several institutes and mainly funded by the Danish Agency for Science, Technology and Innovation.

In the South Atlanic, the magnetic field is too steep and too much easterly directed, too weak and still decreasing, says Jürgen Matzka. We want to learn more about the processes in the core of the Earth that are responsible for the weakening magnetic field, but also study the consequences this has for the interaction between planet Earth and space. Similar stations are on Ascension, St. Helena, the Falklands, Hernamus and Sao Paulo. In 2011, three satellites will be sent into space in ESA’s Swarm mission to measure the magnetic field, and the magnetometer station on Tristan da Cunha will be one of the ground stations for this.

We would like to say thank you to all of you for helping making the Magnetometer Station work successfully. Thanks to the Tristan da Cunha administration, Island Council and the whole community for their permission and support. Thanks to our station manager Robin and operator Jason and all people involved offloading and building the station. Thanks for electrical support, carpentry, internet and bringing the stones away from the field around the station and all the other things. Very imprtantly, thanks for all the advice we got on how to proceed with the station to make it fit into the Tristan community. And finally thanks to James and Felicity, for their great hospitality throughout our stay.

Monday 23 November 2009

funny theodolite

Where someone be confused, they will go to something that can make them fell comfortable. one of it is by riding comics or watch some funny pictures. like this...

Tuesday 17 November 2009

The Marines manually track the balloon with an electronic magnetic meteorological theodolite

They're few, they're silent and they can't be detected, but they can track a 60mm mortar round from several miles away.

More than 25 Marines from target acquisition platoon, 12th Marine Regiment, 3rd Marine Division, III Marine Expeditionary Force, combed the ranges of the North Fuji Maneuver Area, Nov. 2-10, to practice their skills in locating enemy indirect firing positions and collecting weather information during Artillery Relocation Training Exercise 09-03.

Of the two sections, radar and sensors, the radar section uses state-of-the-art technology to locate and track indirect fires from enemy positions and determine where the shots originate. In turn, acquired target locations are forwarded to an artillery unit's fire direction center to calculate how to eliminate the threat, according to Chief Warrant Officer 2 John Crites, officer-in-charge of the platoon.

"If we tell you where the enemy shot from, you can bet that's where they're going to be," said Crites who hails from Chicago, Ill.

In reference to artillery, the 'King of Battle,' may be the heavy weights in the fight, but without the information acquired by the target acquisition platoon and the forward observers, the guns would be at a stand still, according to Crites.

The tools the radar section uses for success includes a counter battery radar, a lightweight counter mortar radar and a ground counter fire system that analyzes acoustic sound to locate enemy positions.

During the exercise, the Marines performed tactical day and night movement that included setting up and tearing down their equipment within minutes. In addition, the Marines were careful in selecting each site by considering the radars' ability to observe the battle space, and also local security capabilities such as entry and exit routes and defensive firing positions, Crites added.

Within the platoon, the meteorological team plays an important role in the battlefield as well. One of the ways these Marines collect meteorological data is by using the piloted balloon method.

According to Cpl. Mark Castro, a meteorological Marine with the regiment, the Marines monitor the ascent of a helium-filled balloon at various time intervals. As the balloon changes direction, the team determines the wind's speed and direction. The Marines manually track the balloon with an electronic magnetic meteorological theodolite, a telescope used for measuring horizontal and vertical angles, with the observed azimuth and elevation angles recorded at certain time intervals. Additionally, the Marines factor in predetermined surface temperature and atmospheric pressure from Department of Defense chart tables of the region.

For the gun line, weather data plays an important role in firing accuracy. It determines how the battery will send rounds down range, according to Castro.

According to Col. Keil Gentry the commanding officer of 12th Marines, there has been nearly an 80 percent turnover in personnel from the regiment.

"For most of the Marines and sailors here, this is their first trip to the Fuji area," Gentry said.

Despite the majority of the sections being new, their leaders were proud of the performance of the Marines.

"For some of my guys, this was their first time out in the field, so it was a good opportunity to hone our skills and build a cohesive team from the bottom up," said Sgt. Dennis Littlepage, non-commissioned officer-in-charge of the target acquisition platoon.

Thursday 12 November 2009

Heinrich Wild’s optical theodolite, introduced in Switzerland in the 1920s, had several new features, including an auxiliary telescope

Leonard Digges introduced the word "theodolitus" in his Pantometria (London, 1571). This surveying instrument had a circular ring or plate divided into 360 degrees, and a pivoting alidade with sight vanes at either end. Theodolites of this sort, as well as others with a second pair of sight vanes affixed to the graduated circle, were soon in widespread use. In 1791, George Adams Jr. called this instrument a "common theodolet," reserving the term theodolite for the telescopic instruments with horizontal circles and vertical arcs that had been introduced in London in the 1720s. While the telescopic theodolite was popular in England, Americans preferred the surveyor’s compass and, later, the surveyor’s transit, which were cheaper and more robust. In the 18th century form, the telescope is mounted directly on the vertical arc. In the transit theodolite, which originated in London in the 1840s, the telescope is transit mounted, with a vertical circle mounted at one side. Heinrich Wild’s optical theodolite, introduced in Switzerland in the 1920s, had several new features, including an auxiliary telescope that lets the user read either circle without moving away from the station.

Some theodolites measure horizontal angles with geodetic accuracy. The first instrument of this sort was made by Jesse Ramsden in London in 1787, and purchased by the Royal Society for use on the geodetic link between Greenwich and Paris. The first instrument of this sort in America was made around 1815 by Troughton in London for the fledgling United States Coast Survey.

Ref:

J. A. Bennett, The Divided Circle (Oxford, 1987), pp. 40–41, 146–149, 195–200.

George Adams Jr., Geometrical and Graphical Essays (London, 1791), pp. 220–222 and fig. 5.

Wednesday 4 November 2009

Mounted on the azimuth axis is a magnetic compass

We are proud to offer this beautifully detailed functional and calibrated solid brass reproduction of a precision theodolite. Theodolites are still used today for ultra high precision optical alignment and measurement. There is a spirit level and three adjustable legs for fine leveling. The azimuth and elevation axes can be read on a vernier scale with the assistance of built-in magnifiers. To reduce bearing errors each axis has slow motion controls and the telescope can plunge and reverse. The azimuth axis has a second spirit level mounted on the telescope with a mirror to aid in leveling. Mounted on the azimuth axis is a magnetic compass. The azimuth scale is 5 1/4 inches (13.3 cm) in diameter and the elevation scale is 4 3/4 inches (12.1 cm) in diameter. The theodolite's 22-power non-inverting telescope has two focusing adjustments; one for the precision reticule focus and the other for focusing the target. The telescope uses precision optics and has a brass lens cover. The telescope measures 8 inches (20.3 cm) long. The solid brass theodolite measures 13 1/2 inches (34.3 cm) tall, and weighs 16.4 pounds (7.45 kg).
The theodolite comes complete with a beautiful hardwood case as well as a teak and brass surveying tripod. The teak tripod contains a second round spirit level and the height is adjustable up to a maximum height of 5 feet, 9 1/2 inches (177 cm) with a maximum eye height of 5 1/2 feet (168 cm). The theodolite mount uses large 3 1/4 inch (8.25 cm) diameter course thread. The theodolite and tripod weigh 30 pounds (13.6 kg).
In addition to the tripod , a beautiful solid hardwood case is included to store and carry the theodolite. The case has storage for accessories and includes a plumb. The case features an internal lock and the case measures 16 1/2 inches (41.9 cm) long, 8 3/4 inches (22.2 cm) deep, 7 1/4 inches (18.4 cm) tall, and weighs 8 pounds (3.6 kg). Note that this theodolite is fully functional and certified accurate for surveying.
The Polished Brass Theodolite, hardwood case, and teak tripod is offered for $2,375.

Sunday 1 November 2009

Search Geographic Surveying Instrument products in China, Search Geographic Surveying Instrument manufacturers & suppliers in China;


Product Description

Laser Theodolites DE series can be convenient to focus and adjust the laser brightness and you can order laser plummet as you like. Also, the laser brightness and focus are adjusted.

More Product Features
Trademark: UNICOM-OPTICS or Neutral English
Model NO.: DE5B-L
Standard: Iso
Productivity: 5,000pcs/year
Unit Price/Payment: FOB USD935.00/pc
Origin: Tsingtao
Packing: Carton
Min. Order: 1
Transportation: By Air
Company: Tsingtao Unicom-Optics Instruments Co., Ltd.

Sunday 25 October 2009

Oregon County Surveyors



The purpose of this Association is to promote public works activities, including the construction and maintenance of roads and appurtenances to recognized engineering standards in the counties; to promote the professional application of land surveying; to promote the ethical practices of these professions; and by the exchange of ideas, give all counties in Oregon the advantages of these professions in all phases of county services.

http://www.aocweb.org/surveyors/

Tuesday 20 October 2009

Nikon NPL-632 Total Stations deliver a versatile, easy-to-use platform to help you get the job done right


NIKON NPL-632

$8,610.00



Nikon NPL-632 Total Stations deliver a versatile, easy-to-use platform to help you get the job done right. Featuring a CompactFlash (CF) slot and a USB port, the NPL-632 total station make data transfer a breeze.

The NPL-632 has reflectorless capabilities that expand the environments you can survey without sacrificing speed or accuracy—you can survey in areas where using a prism would be impossible or dangerous. Up to 650' away to most surfaces, the NPL-522 maintains mm accuracy and pin-point sighting. The Nikon exclusive focus targeting system eliminates reflected shot distance errors experienced by other brands.

1" Angle Reading / 2" Din / 650' Prismless Range / 16,400' EDM Range with single Prism / 26X Scope / Long Battery Life / Waterproof IPX-6 Construction

Combined with the powerful On-Board Data Collection ,
Stakeout & COGO software this multi-media , Prismless
Total Station is a turnkey stand alone solution for most any
Land Surveying application. The USB memory slot accepts
any STD USB memory stick and allows (with the included
PC software "Connex") , the fastest dtat mamgement in the
business.

BTS series Total Station


Product Description

Index: Telescope
Length of sleeve: 150mm
Aperture: 45mm
Telescope: 30x
Image: Erect
Field of view : 1o30'
Shortest distance: 1.5m

Electronic measurement:
Mode of measurement: Measuring Mode
Signal collection: 2 Signals for horizontal 1 Signal for vertical
Accuracy: 2"
Minimum reading: 1"/5"
Diameter of circles: 71mm
LCD: Double Chinese digital

Compensator
Sensor: Compensation
Range of compensation: +/-3'
Accuracy of compensation: +/-5"

Date communication
Date output interface: RS232C

Optical plummet
Magnification: 3x
Field of view: 5o
Range of focusing: 0.5m-infinite

Bubble
Plate level: 30"/2mm
Circular level: 8'/2mm

Lllumination
LCD: yes

Battery:
Specification: Rechargeable batteries
Time Complete unite: 4h
Time Angle measurement: 20h
Voltage: 7.2V
Capability: 2.2Ah

Instrument
Dimension: 114x375x342
Weight: 5.6Kg

Measuring distance
Measurement: 1.5Km/single prism 2.1Km/triple prisms
Measuring accuracy: +/-(5mm+3ppm)

Minimum reading
Measuring mode: 1mm(0.001ft)
Tracking mode: 10mm(0.01ft)

Measuring speed
Accurate measuring mode: 2.5seconds
Tracking mode: 0.5seconds
Range of atmosphere correction: -99ppm-+99ppm (step 1ppm)
Range of prism constant correction: -99ppm-+99ppm (step 1ppm)

Memory points inside: 8000



Sunday 18 October 2009

Theodolite Survey in surveying theory and practice

To verify the reliability of the Survey of some map, we decided to test the angular distances between monuments using a theodolite. a tall multi-storied building was selected as the base of the theodolite readings. The roof offers a good view of all the main monuments.

The theodolite was calibrated and aligned to magnetic north (MN) with a compass and positioned on the south-east corner of the building. Readings were taken in clockwise order from MN, starting with site no. 1. The angular difference between a) two monuments and b) the gross offset from MN was measured and recorded. Due to obstruction by a water tank of the field of view between angles 240° and 350° along the Western horizon, the theodolite was repositioned on the NW corner of the building, reset and re-calibrated with the standard reference and the NS baseline. Due to these adjustments, both theodolite positions can be taken as one, called TP. Interestingly, no monuments were found in line with magnetic north or south, such that the north-south is not emphasised. In contrast, the east-west line is prominently represented in both the terrestrial and celestial schemes. To us, this suggests that the east-west line is the more important basis of calculation in astronomy.

Wednesday 14 October 2009

Moments in Kentucky Legislative History

In a step toward settling Kentucky’s boundary dispute with Tennessee, the Kentucky General Assembly gave final approval on November 22, 1821, to a line marked by William Steele, surveyor for Kentucky, and Absalom Looney, surveyor for Tennessee. The entire dispute between the two states was not completely settled until 1859 with a boundary that cost Kentucky a considerable amount of territory.



Surveyor’s theodolite used by Robert Alexander to survey the southern border of the Jackson Purchase. At the behest of the legislature, Alexander was appointed by Gov. Gabriel Slaughter in 1819 to survey the Kentucky-Tennessee border in the former Chickasaw land between the Tennessee and Mississippi Rivers. Donated by Alex Alexander. KHS Collections.

Friday 9 October 2009

THeodolite Optical


Product Description

Geo-Tech's best selling 5" electronic theodolite 
without compensator
 

Features:
 
Water resistant, sealed construction
 
2 large LCD panels with easy to read numbers
 
state of the art glass encoder
 
Switchable horizontal and vertical angle readout
 
Built in cross hair and display panel illumination
 
Rechargeable on board battery & dry battery box supplied
 
removable tribrach for multiple set ups
 

Specifications
 
Telescope: upright image
 
Length: 155mm
 
Objective aperture: 45mm
 
Magnification: 30X
 
Field of view: 1degree 30'
 
Resolving power: 2.5"
 
Shortest focus distance: 1.3m
 
Electronic angle measurement: 360 or 400g
 
Min. reading: 1"/5"
 
Accuracy: 5"
 
Optical plummet:
 
Mag. 4x
 
Field of view: 5degree
 
Focusing range: 0.5m-
 
Power supply:
 
AAx4 (6hrs)
 
rechargeable battery: 6v(15hrs)
 
Weight: 4.4kg/6.8kg with case

Packing:

1unit/ctn

Model NO.:

GTH-05

Standard:

Export Standard

Productivity:

500units/year

Unit Price/Payment:

T/T, L/C

HS Code:

90152000

Trademark:

Geo-Tech,Neutural Packaging or customer's brand

Origin:

China

Min. Order:

10units

Transportation:

By air, by sea or by courier

Friday 2 October 2009

Diagram of a Pibal Theodolite

This is a illustration depicting David White 6061, 47 and early Warren-Knight models 47, 474 and 84 etc. Pibal Theodolites. A few units were also produced in the 1940's by Seiler Instruments under contract. The illustration and units mentioned above differ slightly from the current Warren-Knight production units in the style of the battery case. See the Pibal Models pages located on this site for for information on the variants of theodolites that are similar to this one as well as some interesting others.

Note that Warren Knight also makes a digital unit that looks quite a bit different than this one. Other digital theodolites as well as currently marketed balloon theodolites are featured on the Manufacturer's Pages on this site.

There are at least three prism types used in balloon theodolite optical paths, and a radically different optical path utilized in a marine theodolite.