Kinematic Tracking and Laser Range Finding
Introduction of Kinematic GPS
Kinematic GPS is a satellite navigation system that enables information obtained from satellites to be accurate and enhance precise positioning from the remote satellites (Wang 203). It uses carrier waves to transport and process data, using one control station to provide real-time images, which are extremely accurate in position. It is mostly used in geographic and hydrographic survey whereby the signals are aligned by the navigation receivers which contain the pseudorandom binary sequence. The method of positioning is known as code based positioning because the receiver interprets and uses these pseudorandom codes, which are transported by more than one satellite so as to pinpoint the exact ranges of each satellite. These locations of each post are then used to show the exact location with just an error of centimeters. For objects that require more accuracy, the kinematic GPS uses carrier waves of a higher magnitude which will display more accurate data through the code based positioning.
The range is quantified by finding the carrier cycle numbers between the station and multiplying by the wavelength of the carrier. The ranges which have been calculated will, however, include errors which arise from tropospheric delays, ionospheric delays, as well as ephemerides. Kinematic tracking using GPS requires the transmission of measurements to the rover station from the base station so as to eliminate these errors (Wang 204). The ambiguity resolution is a prerequisite as it helps to find the number of whole cycles. It is the rovers that determine the positioning of satellites using calculated algorithms that fuse with the ambiguity resolution, and the positioning accuracy by the rovers is affected by issues like the precision of the differential corrections and the distance from the base station. The selection of the area site is mandatory for reducing the effects of the environment like multipath and interference, as well as the value of the base station and strength of the antennas.
The principle of LiDAR and TLS
The LiDAR principle is the same as Electronic Distance Measuring Instrument (EDMI) whereby a pulse-like laser is shot from a transmitter and the energy is reflected then contained (Wang et al 504). The reflector is determined using the time of travel of the laser between the reflector and transmitter and it could either be a natural object or artificial; like a prism. The range of the LiDAR is mainly measured by the distance calculated while other complex measurements and calculations give coordinates of the reflector.
Use of laser scanner technology in geological expedites is mainly for displaying images of relief through high-resolution digital models which display in 3D (Hyyppä et al 9). The LiDAR techniques are used in landslides, debris flow, and rock fall. The functions of the models are categorized into four classes; hazard assessment and mapping susceptibility, detection of mass movements, monitoring, and modeling. Emphasis is mostly on how LIDAR-derived HRDEM is used to study landslides and related phenomenon. The two most important remote sensing techniques which are formulating landslide studies include light detection and ranging and interferometric synthetic aperture radar (InSAR). These techniques are usually ground-based and are often focused on the identification and quantification of little displacements over a wide range. Laser scanning provides point clouds which are of high resolutions over the topography and contains activities that range from monitoring and deformation to mapping and rock fall displacements.
A LiDAR is made up of a scanning device as well as a laser beam transmitter. The two primary processes of determining the range are pulse and phase techniques. The phase method gives a more precise interpretation but has a quite limited range (Murgoitio et al 153). The pulse method, on the other hand, provides a wider range and is used in both the TLS and ALS for monitoring of relief activities on the earth surface like landslides (Wang et al 26). The TLS and ALS sensors transmit waves that get hit by relief objects as well as man-made features and document the returning signal.
Introduction to LiDAR and its applications
LiDAR is majorly used in landslide analysis so as to come up with on-point high-resolution digital evaluation models (HRDEM) in uneven networks, which are 2.5D displays of the topography (Jaboyedoff et al 6). The density is reliant on the position of the sensors for determining the resolution of the terrestrial laser scanning or airborne laser scanning. Laser is an acronym and stands for Light Amplification by Stimulated Emission of Radiation. A laser is an instrument that lets out beams of highly charged electromagnetic radiation. Laser devices are used for the obtaining of 3D data on the topography at a very fast rate. The laser range finder/laser scanner is formulated in two ways, depending on the location of the sensor: ground centered for TLS and airborne for ALS (Murgoitio et al 153).
The location of the ALS is usually determined by a GPS and information obtained is stored by a technological storage device. The location of the TLS is not determined in the field but can be possible if fitted with its own internal GPS. It makes it easier to geo-analyze the point cloud of the TLS by either using another existing point cloud or using ground control marks.
Hyyppä, J. U. H. A., et al. “Unconventional LIDAR mapping from air, terrestrial and mobile.” Proceedings of the Photogrammetric Week. 2013.
Jaboyedoff, Michel, et al. “Use of LIDAR in landslide investigations: a review.” Natural hazards 61.1 (2012): 5-28.
Murgoitio, Jayson, et al. “Airborne LiDAR and terrestrial laser scanning derived vegetation obstruction factors for visibility models.” Transactions in GIS 18.1 (2014): 147-160.
Wang, G., et al. “The integration of TLS and continuous GPS to study landslide deformation: a case study in Puerto Rico.” Journal of Geodetic Science 1.1 (2011): 25-34.
Wang, Guoquan, et al. “Delineating and defining the boundaries of an active landslide in the rainforest of Puerto Rico using a combination of airborne and terrestrial LIDAR data.” Landslides 10.4 (2013): 503-513.