The new dimension in measuring technology.
Abstract
Outstanding and enhanced total station functionality, GNSS connectivity, high resolution digital imaging and 3D laser scanning; this is mergeTEC a key component of the Leica Nova MS50.
mergeTEC not only merges the technologies it also merges the data. Images are referenced to total station measurements, total station measurements are complemented by 3D point clouds, which, themselves are colored by the image information. All data perfectly fits within the same coordinate system, globally referenced by GNSS measurements or by measuring known points.
How the Leica Nova MS50 – the world’s first MultiStation – can combine total station functionality,
GNSS connectivity, digital imaging and 3D laser scanning in a single instrument and how the separate sensors work will be presented in this white paper.
Introduction
Leica Nova MS50 embodies 90 years of innovative thinking of Leica Geosystems to develop precise, reliable and flexible technologies.
The Leica MS50 is part of the Leica Nova solution which contains:
Outstanding surveying instruments, built on the latest technologies,
Integrated dataflow, straightforward and easy to understand workflow,
Services and support, accessible worldwide.
Faster, Better, Smarter, Simpler. These key words describe the benefits of Leica Nova; a unique solution that covers the complete process from capturing and visualising data, taking decisions and delivering.
The Leica Nova MS50 includes precise 3D laser scanning, extensive and precise total station capabilities, digital imagery and GNSS connectivity. Thanks to mergeTEC, the Leica Nova MS50 not only combines the hardware but also merges the data itself; images are synchronised with 3D laser scans and the scans tied into total station measurements.
The Leica Nova MS50 allows the user to decide on-site which measurement technology to use to fulfil his measurement tasks. The results are available directly in the field, for example the volume of a stockpile derived from point clouds which have been scanned with the Leica Nova MS50.
Leica Nova MS50 – the world’s first MultiStation
The Leica Nova MS50 is the world’s first MultiStation and features outstanding precision, accuracy, efficiency, quality and versatility. The MS50 provides an angular accuracy of 1” (according to ISO 17123-3) and a new optical-distance measurement system (EDM) based on wave form digitizing technology. The EDM measurement accuracy is 1mm + 1.5ppm onto prism (according to ISO 17123-4) and 2mm + 2ppm for measurements onto any surface.
The new PinPoint R2000 EDM measures distances to any surfaces up to 2,000m and distances up to at least 10,000m onto a single prism. The new EDM not only enables extended measurement range onto any surface, but also significantly reduces measurement time. Onto prisms, the distance measurement time is reduced by around 50% which has a time saving impacting the overall measurement time.
The mechanical design of the MultiStation has been developed for highest protection against environmental conditions. The Leica Nova MS50 fulfils IP65 standards and withstands the MIL standard blowing rain test. This is the highest protection for any robotic total station currently available. The MultiStation emphasizes high-dynamic automation with its best-in-class speed and acceleration capabilities. Furthermore, PowerSearch functionality supports the Leica Nova MS50 to find the target points quickly and efficiently. A combined USB–RS232 interface at the nonrotating
part of the MultiStation as well as Bluetooth and WLAN ensure fast data transfer. A long-range Bluetooth radio handle can be connected to the MultiStation and ensures remote working ranges up to 1,000m.
The Leica Nova MS50 offers enhanced imaging functionality by implementing two cameras: the overview and the telescope camera. Both cameras deliver 5 megapixel resolution images for accurate image assisted surveying and high quality documentation.
The overview camera is located in the upper part of the telescope, while the telescope camera is located in line with the optical axis and has the full 30x magnification of the telescope optics.
The live video stream, which is provided with up to 20 frames per second on the display, can easily be switched between overview camera and telescope camera.
Autofocus functionality increases the measurement efficiency and reduces the fatigue of the operator’s eyes.
A unique functionality of the Leica Nova MS50 is 3D laser scanning. The scanning functionality is seamlessly integrated into the standard workflow of a total station. This allows the 3D laser scans to always be in the current coordinate system of the MultiStation. Known setup routines (e.g. set azimuth, known backsight, resection) are used and the point clouds are automatically registered directly in the field. The onboard 3D scan viewer allows the user to verify and check the point clouds forcompleteness directly in the field. Scan shadows can be identified on site which minimizes the necessity for costly returns for re-measuring. Surfaces and volumes can be calculated with the QuickVolume application. Additional single measurements from the setup complete the data.
mergeTEC is the fusion of the latest innovative technologies and combines:
- enhanced and outstanding total station functionality
- GNSS connectivity
- digital imaging
- 3D laser scanning
Consequently, mergeTEC enables the user to select the appropriate measurement technology for the corresponding measurement tasks within one instrument. mergeTEC also guarantees that the captured complex 3D data is referenced to each other. The user does not need to care about referencing data among a multitude of scans, images and TPS measurements. He can use known TPS setup routines such as “set orientation”, “known backsight” or “resection”.
Enhanced and Outstanding Total Station Functionality
The Leica Nova MS50 emphasizes enhanced and outstanding total station functionality. The motorization, based on Piezo-technology, allows very fast telescope movements without any noise pollution. Furthermore, the fast motorization and the automatic target aiming technology ATR (automatic target recognition) enable best tracking performance onto a moving prism.
The Leica Nova MS50 uses a distance measurement system which allows highly precise and fast measurements. Ranges onto any surface are possible up to 2,000m and onto a single prism up to at least 10,000m.
The Leica Nova MS50 uses the SmartWorx Viva field software onboard. The SmartWorx Viva field software is well-known from Leica Viva total stations and is intuitive and easy to operate. SmartWorx Viva ensures the complete integration of the new measurement technologies such as imaging and 3D laser scanning into the standard measuring workflow. This makes it easy for the user to learn and to operate the instrument. Dedicated onboard software applications (e.g. for tunnelling, rail, road) extend the application area of the Leica Nova MS50.
GNSS Connectivity
GNSS is fully integrated in the workflow and the data structure. The Leica Nova MS50 allows SmartStation and SmartPole setup with several Leica GNSS smart antennas. This enables direct georeferencing without need for sighting known points. Thanks to enhanced Leica Geosystems GNSS technologies, the position can be defined quickly and reliably.
Digital Imaging
mergeTEC and the Leica Nova MS50 also address the widespread trend towards digital image integration. Digital imaging has become a central element in the measuring process. Therefore, the MultiStation features two high resolution 5 megapixel digital cameras – the overview camera and the telescope camera which is located in the optical axis of the telescope.
The live video stream can be shown on the instrument’s display or on the controller and can easily be switched between overview camera and telescope camera. When standing at the instrument, the user has the choice between looking at the live video stream and looking through the telescope. Digital imaging on the Leica Nova MS50 enables enhanced image assisted surveying and image documentation. Digital imaging improves the measurement efficiency, quality and documentation of the field measurements.
Image Assisted Surveying
Image assisted surveying supports the operator with Tap&Turn and 3D data overlay functionality, making the measurement process faster, simpler, and more comprehensible. Tap&Turn is a comfortable and efficient way to measure using the live video stream. The instrument turns to where the user taps on the display, directly at the instrument or from remote with a controller. The 3D data overlay functionality increases the measurement quality in terms of completeness by displaying measured points and points from the job as 3D data overlay. The overview camera helps the user to roughly aim onto the target. By using the telescope camera, the target can be precisely aimed based on the live video stream and the 30x magnification (Figure 5). An angular accuracy of 1” (according to ISO 17123-3) of the measurement can be achieved by using the live video stream from the telescope camera to aim onto the target.
Image Documentation
High resolution images can be captured with the overview camera and the telescope camera. These
images can be directly be linked and referenced to the measurements. The possibility to capture images of each measured point improves the documentation of the field work. Furthermore, sketching functionality allows making notations directly in the images for better understanding of what has been measured. The high resolution images from both cameras can be used for photogrammetric processing. The photogrammetric resolution of 1 pixel of the telescope camera corresponds to 5cc which results in a resolution of 2mm @ 200m.
Telescope Camera
To enable precise measurements based on the live video stream, the telescope camera is located on the optical axis of the Leica Nova MS50. Thus the full 30x magnification of the high quality optics of the telescope is available on the live video stream. To maximise the working comfort, reduce the fatigue of the user’s eyes or to enable focusing from remote, mergeTEC comes with autofocus functionality. The autofocus functionality is executed either as a single autofocus or as a continuous autofocus which always ensures a sharp image.
The telescope has been designed such that a focussed image is simultaneously available on the live video stream and on the optical path through the ocular (see Figure 6). Parallel use of the display and looking through the ocular is therefore always possible.
Best optical quality is guaranteed by high-precision optical elements (see Figure 7) such as the porro-prism, which reflects the incoming light onto the CMOS sensor of the telescope camera and directly to the ocular for visual aiming. The focusing module (focusing lens and slider bar to move the lens along the optical axis) require micrometer tolerances in the production process to guarantee 1” angular measurement accuracy of the MultiStation.
Adjustment and calibration processes are key factors to achieve the highest quality of the imaging functionality.
The Leica Nova MS50 has been designed to use both, the visual path through the ocular and the live video stream for aiming at the target point. The possibility to use the camera and the ocular at the same time is important to ensure versatili-ty in the measurement processes and is required for highest measurement accuracies under difficult light conditions.
3D Laser Scanning
Thanks to the new electro-optical distance measurement system based on the wave form digitizing technology, the fast and precise Piezo-motorisation, the high processor power and Leica Geosystems’ scanning expertise, the Leica Nova MS50 integrates 3D laser scanning functionality into the regular measuring workflow of a total station. Detailed point clouds can be combined with topographic survey data.
EDM – Electro-Optical Distance Measurement
The Leica Nova MS50 features an electro-optical distance measurement system based on the wave form digitizing technology (WFD). WFD is a specific type of a time-offlight measurement system which sends out a signal and detects and stores a digital signal vector. The advantages of the WFD technology are the fast distance measurements, small laser dot size, high measurement accuracy and the long ranges which are available at the same time. Compared to the phase-based EDM technology, the distance measurements with the WFD technology are approximately 50% faster onto prisms but the measurement accuracy is slightly lower (see Table 3). Compared to pure time-of-flight measurement systems, the WFD technology results in better measurement performance, which shall be explained in the following.
The WFD based EDM sends out signals. When a signal is sent out, a small part of each pulse gets directly guided onto a photo detector and serves as internal calibration measurement. This pulse is called the start pulse. The rest of the pulse is emitted out of the telescope and reflected by the object. The returning pulse is called stop pulse. For every measurement, an internal calibration measurement is done.
For longer distances, the energy and therewith the signal to noise ratio (SNR) of one single returned pulse gets very small. This makes it difficult to extract the stop pulse. Therefore the WFD accumulates signals to the same target multiple times. As more signals are sent out and received, the better the stop pulse can be digitized (see Figure 8). The final distance is defined by the time difference between the start and stop pulse, digitized by the accumulated signals. For quality control, the shape of the start pulse is taken into account when digitizing the stop pulse. If the shape of the stop pulse is not similar to the start pulse, the distance measurement is not valid. This can happen when e.g. an object passes through the laser beam or the angle of incident of the laser beam on the object is very small.
The SNR gets improved by the square root of the measurement time. A measurement time of 9s for example has a three times better SNR than a measurement time of 1s. The selection of the measuring time therefore has an impact on the distance measurement accuracy.
The fast distance measurements, combined with high accuracy and long ranges which are provided by the WFD are prerequisite for 3D laser scanning.
This information is taken www.leica-geosystems.com
This information is taken www.leica-geosystems.com