Leica RTC360 enhancements to increase your efficiency
Data size reduction, adaptive image resolution and tilt accuracy improvements in the RTC360
The Leica RTC360 3D laser scanner combines high-speed scanning and image data acquisition, powered by a truly unique Visual Inertial System (VIS Technology) that’s easy to use for all experience levels. With Leica Cyclone FIELD 360 field application and Leica Cyclone REGISTER 360 office software, the 3D reality capture solution is one of a kind. Since the release of the RTC360 in 2018, continuous enhancements have been regularly released to refine the user experience further.
Below we share two significant enhancements from recent firmware versions 4.0 and 5.0:
Data Size Reduction and Adaptive Image Resolution
3D laser scanners and imaging laser scanners collect large amounts of spatial data in a short period. This collected data is temporarily recorded on a USB storage device for final import and post-processing in office software, such as Cyclone REGISTER 360. If you are working in the field all day long on a complex project with many setups, for example, the data size on the USB storage device will be significant and could complicate data handling.
With RTC360 firmware v4.0, focus on improving data handling was fundamental. We introduced a new Adaptive Image Resolution feature which dramatically reduces the size of imaging data. To achieve general data size reduction, a new scan data format and new image compression algorithm were developed. This new format and compression algorithm reduces the size of the data and ensures the quality of the scan and image data remains high.
Scan Data Format
The reduction of scan data size with the new scan data format is represented in the graph below. It shows the data size in Megabytes per setup without images for all three scan resolutions from the various RTC360 firmware versions that have taken place since its original release in the market.
As you can see in firmware version 2.0, we reduced setup data size by approximately 70% from the initial data size in firmware version 1.50. With the release of firmware version 4.0, data size is reduced by approximately 35% compared to version 2.0. A setup collected with firmware version 4.0 or newer uses only 20% of the data storage compared to the original release of the RTC360 in 2018.
Additionally, in firmware version 4.0, data size was reduced by introducing a new image compression algorithm. The graph below shows that firmware version 4.0 has furthermore reduced data size of more than 30% compared to firmware version 2.0. A setup containing scan and image data collected with firmware version 4.0 or newer takes less than 20% of the data storage compared to the original release of firmware version 1.5 with the RTC360 in 2018.
Adaptive Image Resolution
To save time when importing scan data into post-processing office software, the RTC360 can be programmed to cleverly remove redundant imaging data by simply enabling the Adaptive Image Resolution feature. By default, the RTC360 collects images in full resolution (4000 x 3000 pixels) independently from scan resolution. The RTC360 automatically adjusts its imaging resolution to suit the desired scan resolution by enabling the Adaptive Image Resolution feature. This means that raw images are down sampled for low and medium resolution scans so that each measured 3D point has its corresponding pixel in imaging data. Resolution of images taken with a medium scan resolution is set to 2000x1500 pixels and for low scan, resolution is set to 1000 x 750 pixels. By selecting these resolutions, point cloud colour information is not lost, as shown in Figure 1 below.
Figure 1: Comparison of point clouds colourised by intensity values (left side) and true colours (right side) for all scan resolutions (high, medium and low from top to bottom) with Adaptive Image Resolution feature enabled.
There is no doubt that the new scan and image data formats drastically reduce data size and provide users with peace of mind that data handling is better without compromising the final data quality.
For many projects where the main deliverable is a colourised point cloud, it is highly recommended to enable the Adaptive Image Resolution feature as it optimally reduces setup data size - 10% for medium resolution scans and 70% for low resolution scans compared to setups with the feature disabled. Import time into post-processing office software is improved by up to 60%. There is less data to be read and processed, decreasing data transfer time and producing a “field to final deliverable” quicker than before.
When users are in the field all day and need to complete many setups, they need one storage device that contains all data from their laser scanner. The USB storage device provided with the RTC360 can easily manage all data from a vast number of setups. However, with firmware version 4.0, we enhanced the USB storage device even more. It can store five times more scan setups and setups with imaging compared to the original firmware available at release. If the Adaptive Image Resolution feature is enabled, it can store 18 times more setups. The graph below shows the maximum number of setups stored on the RTC360 storage device per firmware release over the last three years.
As the data size is optimised by using less space, so is the data transfer time. Less time is needed to transfer data. Archiving the data on a permanent storage device is therefore cheaper as users don’t need to spend additional money on hardware or cloud data storage solutions.
High Tilt Accuracy
When the RTC360 was first introduced into the market, the tilt accuracy was specified at 3’ or 180’’ for any tilt of the laser scanner. This solution prevented the need for customers to level the scanner for each setup, however for some specific applications like levelness of a floor or slab, or the verticality or horizontality of an object, the tilt accuracy did not meet requirements. For this reason, an additional focus for levelling the RTC360 on a tribrach or setting-up targets in the field and measuring them with a total station to define the levelled reference for later registration in the office software was a necessity.
Firmware version 5.0, therefore, released a new High Tilt Accuracy feature which significantly improved the tilt accuracy of the RTC360 laser scanner by a factor of 10. With the High Tilt Accuracy feature enabled, tilt accuracy is 18’’ in a working range of ± 5° for the laser scanner’s upright and upside-down orientation. For any greater tilt of the laser scanner or if the High Tilt Accuracy feature is disabled, the previous 3’ tilt accuracy continues to be valid.
Figure 2: High Tilt Accuracy feature on the Settings screen.
To achieve the new High Tilt Accuracy with the existing IMU sensor, our engineers developed a brand new algorithm for processing the IMU data, collected over a 360° rotation around the azimuth axis of the RTC360 laser scanner. To achieve the High Tilt Accuracy, a local gravitational acceleration derived from the last known GNSS position is used to calculate a tilt.
The new high tilt accuracy of 18’’ assures that a point cloud is levelled up to 10 times more accurately than before, allowing users to perform field tasks without additional effort. With the High Tilt Accuracy enabled, the levelness of a floor or a slab, the verticality or horizontality of an object can be checked with an error smaller than 1.7 mm @ 20 m or 3.5 mm @ 40 m, meeting the requirements of typical laser scanning jobs.
Figure 3: Maximum Horizontal/Vertical errors with 18'' of tilt accuracy at a given distance.
To ensure the best possible scan and image data quality and tilt accuracy for your RTC360, please download the latest firmware version, which is available for download from Leica Geosystems’ myWorld customer portal.
Senior Product Engineer, Terrestrial Laser Scanning
Reality Capture Division