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The Topcon IS (Imaging Station) is the latest offering from Topcon Positioning Systems’ optical equipment lineup. It is built on the 900 series robotic chassis, however its expanded capabilities go well beyond a typical servo-driven total station. True to Topcon’s philosophy of reaching the masses, they have managed to introduce a relatively affordable scanner that also can be used in the more mundane aspects of surveying as well as in high density scanning operations. Whereas you likely wouldn’t perform a boundary survey with a $100K laser scanner, the IS can easily be used as a conventional total station for such a task. Should a solo or two-man robotic stakeout session be required, the IS will also perform well. If safety, accessibility, speed, or the need of a scanner are the requirements, the IS may be the right fit.
The IS interface is via a single touch screen (mostly legible in bright sun) that has a twenty-four button keypad with a four-position rocker pad. The operating system is Microsoft Windows CE.Net version 4.20. The processor is an Intel PXA255 rated at 400 MHz. Admittedly, I have been a little skeptical of touch screens and Windows operating systems on a total station. However, considering the scanning and imaging capabilities of the instrument, as well as the onboard data collection, I don’t think a DOS-type system would be up for the challenge.
The gun sports two 1.3 megapixel digital cameras. One is above the objective lens and gives a wide angle similar to what the instrument operator would see looking over the scope. The second is coaxial with the scope and displays exactly what an operator would see looking through the scope. Images from both cameras are viewable from the LCD display on the faceplate. Theoretically, using the coaxial camera, you could perform a conventional survey without ever looking through the scope. A virtual crosshair that looks exactly like the crosshair in the scope is overlaid on the image and allows you to collimate a target. The image is refreshed at a rate of up to 10 images per second, which yields a very fluid picture as the instrument as turned.
The crosshair focusing knob is, as would be expected, around the telescope eyepiece, however, the image focus is actually on the right standard just above the vertical and horizontal jog/shuttle knobs. The IS is equipped with autofocus, which worked fairly well, but when it didn’t the jog/shuttle focus knob worked fine. (Jog and shuttle are fast and slow servo speeds).
On the same right standard is the recessed power button and the battery compartment. The instrument is powered onboard by a BT-65Q Lithium Ion battery at 7.4 volts and 5000 mAh, which are similar in appearance to a camcorder battery. Battery life is respectable. Whether running the robot or performing scanning operations, I was able to get 5-6 hours of use. The unit is shipped with three batteries to ensure a full day’s work. There is also an external power port. My one criticism of the battery life is the speed at which batteries depleted in the instrument while on the shelf. If the battery was charged a week ago and left in the instrument, chances are it is dead today. This means that the user will have to be vigilant about battery management.
On the left standard there is a rotating antenna for the onboard spread spectrum radio. I can’t say enough good things about internal radios on a robot, and particularly the one Topcon has in place on the IS. Having the built-in radio means that the time required to set up the IS is basically the same as setting up a conventional total station. The range of the radio was impressive and went farther than I would typically feel comfortable with when using a robot.
Below the antenna is a hatch that accesses a Compact Flash Card slot. As issued, the slot was occupied by a Wireless Local Area Network Card. WLAN allows the instrument to be operated remotely as an imaging total station. At 10 frames per second, bandwidth becomes vitalwhere Spread Spectrum just can’t keep up, WLAN can. At present though, WLAN is limited to a range of about 300 feet. So while the instrument can be operated remotely as a "conventional" instrument, being able to do so will require the user be within 300 feet of the instrument. Eventually, once this limitation is overcome, a robotic user will be able to direct the instrument to a building corner or some other feature using the image displayed on the data collector and collect a reflectorless shot just as though he or she was behind the instrument.
At the bottom of the left standard is a USB port for quickly uploading and downloading vast amounts of photo and scan data. The IS also has an integrated Bluetooth radio for wireless connectivity and is equipped with a built-in optical plummet.
Robotic and Conventional
Onboard data collection seems to be all the rage in Europe and elsewhere, but in America, the external DC is still king. Given the right type of work, I could seriously go for an onboard collector after working with TopSurv 7 on the IS. The onboard TopSurv 7 had the same look and feel as the TopSurv 7 I was using on the FC-2200 external data collector.
Topcon’s pursuit of developing an "end to end solution" for surveyors (everything from field equipment to office software and all points between) has resulted in a commitment of some serious resources focused toward various components that they had not previously keyed on before such as data collection. While discussing this with my contact at Topcon, Scott Langbein, Senior Manager, Product Marketing, I learned that Topcon has put together an impressive line up of intellect from some distinguished names in data collection. This was easily apparent in Version 7’s capabilities and easy work flow.
Navigating through TopSurv’s various menu options is straightforward. According to Topcon, a user will only need to navigate through a maximum of four icons to reach any function. The more common ones I used were typically only two icons away. Jobs are stored in a *.tsj file and all raw data and coordinate data is stored within it. True to the concept of utilizing images in surveying, Topcon has not only incorporated a digital camera in the instrument, but also in the FC-2200 itself. This allows you to capture an image of a feature and attach it as a note to a stored shot. In the office, using the Topcon download software, Topcon Link, points can be viewed along with their linked images.
One of the notable features I found in TopSurv allows the user to quickly toggle the method used for collecting points, switching from "single face one" observations, to "average of multiple face one" observations, to "sets" was uncomplicated. The interface for performing sets robotically was as clean as I’ve used. Instead of being fully automated, before each pointing measurement is made, the user must accept the data on the screen. So if the robot is supposed to be pointed at the backsight, somewhere near zero degrees, and it accidentally got locked on something it shouldn’t have, you can initiate one of several search tools to get your wayward robot back on target before proceeding with the rest of the set.
Another thing I really liked about TopSurv is its full-featured offsetting capabilities which I found particularly suited to reflectorless locations of building corners, etc. I also really liked the way the system communicated. With the IS selected and configured in the data collector to communicate via the built in 2.4 GHz radio, the data collector immediately searched for the IS, requiring only a few seconds. The Bluetooth sniffed the RC-3 and I was ready to work. The FC-2200 is also equipped with a snap-on radio bundle, the RS-1. With this setup, I was completely cable free at the instrument and the rod.
Topcon has always employed passive tracking. With this technology the prism locks onto anything closely resembling a prism. Older passive tracking instruments may lock on to something that really doesn’t even look like a prism, like a shiny windshield, a piece of chrome or of course, the infamous tail light.
Even though Topcon uses passive tracking, for initial locking, Topcon has the RC-3. The RC-3 sends out an infrared signal that is sensed by the robot and directs the robot to the actual prism. This can be very handy in difficult environments, and very quick. I was really impressed by the range at which I was able to acquire the prism using the RC-3. At 1400 feet I was able to direct the IS to me across a moderately busy highway. I was also able to do the same at very short rangesas short as 20 feet away.
I have extensive experience with older Topcon robotic technology and it can be a real nuisance when the instrument locks onto shiny objects like those mentioned above somewhere away from the prism. However, the IS seemed highly resistant to such distractions. To test it, I went to a local grocery store on a Saturday afternoon. I set up the 360-degree prism across the busy parking lot (about 400 feet away) and turned the instrument a few degrees from it. I then initiated a general search in which the instrument simply looks for a prism (no RC-3 to assist). The instrument began its boxed search, scanning left and right, up and down, stopping occasionally as it passed a shiny reflective imposter. Here is where the IS separated itself from my past experiences with Topcon robotics. Instead of simply loitering on the reflection of the sun on a shimmering chrome bumper, it would pause for less than a second as it interrogated the object and then move on until the prism was within view, at which time it snapped to attention. While I’d much prefer the IS not even be distracted by reflective signals, it is a passive tracking system. The fact that it was able to intelligently distinguish the 360-degree prism from the glistening chaff around it was very encouraging.
I can’t conclude this section without discussing the unbelievable reflectorless capability of this instrument. It is spec’d to have a reflectorless range of just over 6500 feet (2000 meters). Here are some real world measurements from a real world set up to typical objects.
As a test of beam width I shot a street sign and the galvanized pipe for sign at 501 feet with identical results. This shows it wasn’t getting some reflection on objects beyond the post and from the post and then returning some average distance beyond the post. Beam width is as important as range for any reflectorless instrument, and will determine the situations you will be able to effectively use it. Again for the purpose of testing beam width, I successfully measured to the top nut of a fire hydrant at 359 feet.
I can think of a few 1A certifications we did on existing cell towers which required triangulated intersections because the range was too great for our reflectorless total station. That would not have been the case with the IS. I was able to shoot a steel self support tower at 1,460 feet away, a white water tower at 2,560 feet, and at 4,065 feet I was able to shoot the white antenna array at the top of a steel self support tower, but not the steel structure itself.
I shot a light brown power pole at 3,740 feet, a flat black mail box at 827 feet, a concrete power pole at 4,655 feet, and a wood privacy fence at 4,161 feet. I was lusting a little after the results of this reflectorless exercise.
A Half-man Crew?
Total stations reduced a typical survey team to a two-man crew, and robotics and RTK require just a one-man crew. But a half-man crew is the best way I can describe the manpower needed for the scanning application of the IS.
I took the IS to our local city park to do a few mock scanning projects. One was a WPA-built rock-lined drainage channel about four feet deep and about eight feet wide. Because the scanning function resides in the TopSurv7 onboard software, I was able to set up a job just like any other boundary or topographic survey.
I first set up on an unmarked random point where I felt I could do the most damage. Using the long range reflectorless capability of the IS, I measured to three different points that were precise, seemingly stable, and well distributed beyond the extents of my project. Using one of the remote points as a backsight, I began scanning.
Scanning is fairly simple to set up. In the scanning routine, you identify the upper left and lower right extents of your scan area on the image shown on the screen. Next, you select the density you want the instrument to record scan points. This can be done by specifying a vertical and horizontal angular distance or by defining a horizontal and vertical linear distance interval. If you choose the linear approach, you can either specify the approximate distance you will be observing, or you can point to an area you feel represents the approximate distance of the scan area and take a shot. The IS then trigonometrically determines the angular spacing appropriate for that distance.
Once initiated, the instrument then records photos from its wide-angle camera of the entire scan area. The images are later stitched together seamlessly for a mosaic of the scan area. You can perform the photo mosaic routine without actually performing a scan. This allows you to document a setup with a full 360-degree panoramic view of a set up for any survey: construction, boundary, topo, whatever. Consider the benefit to your documentation that a feature like this represents.
Once the images have been captured, the instrument prompts you to start scanning. Once fired off, the instrument turns to the upper left corner and begins a very quick left to right, down, right to left, down, sweep of your selected area, collecting at a rate of up to 20 shots per second. That’s right, twenty shots per second. On the screen you can watch as the display showing your scan area becomes populated with tiny squares representing each shot being taken. While this is nowhere near as fast as an actual laser scanner, it is very quick.
I scanned a 100-foot-tall steel derrick at a 0.2 foot by 0.2 foot interval from a couple hundred feet away. This took a little less than two hours. Scanning the channel at something more like a 0.5 foot interval went much faster. With the resection routines in the TopSurv7 software, I was able to work basically control free. At the beginning of each setup, I would observe the three distant points and determine my position. The statistics allowed me to determine that I had a good solution, and having three points offered me a little redundancy. Had it been a real job, I would have had more.
While the scanner was working, I found myself pondering the meaning of life as I sat on the bank of the rock channel watching the tiny stream flow beneath my feet. I had the time, and the IS didn’t really need me once I set it on its task. It obviously wasn’t completely autonomous, but it was close. Close enough to be less than a full one-man crew. Like I said, perhaps more like a half-man crew.
Once the scanning was complete, I used Microsoft’s Activesync to move the information from the instrument to my computer via USB. Once on the computer, I imported the files to Image Master for IS. Topcon offers two products with the Image Master label. One is for the IS, the other for photogrammetric work, Image Master Pro. Image Master for IS has some basic tools for working with scan data registration (I used the By Occupied and Backsight Points method), photo overlay, Triangulated Irregular Network creation, measurement tools (the derrick was 101.15 feet tall according to Image Master), polyline creation and editing tools, and exporting tools. The workflow for most users will likely entail importing the scans and photo mosaics, viewing and editing the points (I like the color by elevation for this), manually creating breaklines where needed, developing a TIN and exporting the TIN as a .dxf file to a CAD program for final modification. While I would have liked to have seen more filtering tools than were available, Image Master for IS worked well for its rudimentary purpose.
In the end, if I needed a fully dedicated laser scanner, I’d go for a laser scanner. However, if the idea of a scanner seems beneficial to your work load, but not enough to justify the cost, the IS may be a good option. It performs great as a robotic total station and is also able to snag a lot of data very quickly as a scanner. Add photo documentation as a collateral benefit and you’ve got a nimble piece of gear with an attainable price tag.
Shawn Billings is a licensed land surveyor in East Texas and works for Billings Surveying and Mapping Company, which was established in 1983 by his father, J. D. Billings. Together they perform surveys for boundary retracement, sewer and water infrastructure routes, and land development.
A 1.793Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE