Development of a Network RTK Positioning and Gravity-Surveying Application with Gravity Correction Using a Smartphone

Abstract

This paper proposes a smartphone-based network real-time kinematic (RTK) positioning and gravity-surveying application (app) that allows semi-real-time measurements using the built-in Bluetooth features of the smartphone and a third-generation or long-term evolution wireless device. The app was implemented on a single smartphone by integrating a global navigation satellite system (GNSS) controller, a laptop, and a field-note writing tool. The observation devices (i.e., a GNSS receiver and relative gravimeter) functioned independently of this system. The app included a gravity module, which converted the measured relative gravity reading into an absolute gravity value according to tides; meter height; instrument drift correction; and network adjustments. The semi-real-time features of this app allowed data to be shared easily with other researchers. Moreover, the proposed smartphone-based gravity-survey app was easily adaptable to various locations and rough terrain due to its compact size.

Assessment of 3D Models Placement Methods in Augmented Reality

“…The unavoidable white noise in the gyroscope data causes some rotational angle drift. Over time, this noise builds up and leads to inaccurate placement outcomes [52].…”

A Survey of Marker-Less Tracking and Registration Techniques for Health & Environmental Applications to Augmented Reality and Ubiquitous Geospatial Information Systems

“…This can be converted into yaw, pitch, and role values and the pose with 3 degrees of freedom. Before any use, raw data must be rectified of any bias (the distance between the data center at zero) and scale (the difference between the range of data from the sensor and real meaningful data) [37].…”

“…Accelerometers measure linear acceleration from both the linear movement of the device and the Earth's gravity [103]. The rotation around the x-(roll) and y-(pitch) axes can be calculated from the accelerometer's raw data [37]. Because both gyros and accelerometers are affected by errors, they usually fuse to compensate for the weaknesses of each other [104].…”

“…Gyroscope data have inseparable white noise that induces some drift in the rotational angle. This noise accumulates over time and produces inaccurate results [37]. Drift is the most important weakness of gyros and may accumulate up to 10 degrees per minute overtime [102].…”

“…Although the nominal accuracy of digital compasses is reported as 0.5 degrees by manufacturers, it can degrade significantly (to six degrees in some cases) with vicinity to cars or other sources of the electromagnetic field [2]. The fusion of the compass with inertial sensors can improve the accuracy of yaw rotation by using its pitch and roll to map magnetometer data to the horizontal plane [37].…”