The main goal of the GAL project was to revisit the method of strapdown airborne gravimetry (SAG) in light of the Galileo^(a) system. In traditional SAG, strapdown inertial measurements and GPS ranging signals (code and phase measurements) are used, where strapdown inertial measurements are obtained from inertial measurement units (IMUs).

Gravimetry is the measurement of the strength of the gravity field of a celestial body. In modern geodesy, many times, gravimetry is synonymous to the measurement of the differences between an actual gravity field and a [global] model of that gravity field. The Earth gravity field is approximated by global and local models that are computed by geodesists from gravity measurements and some other types of geodetic observations like level differences or deflections of the vertical. While global gravity models might be highly accurate they are of limited spatial resolution –i.e., of 100 km wavelengths and lower– and local gravimetric densifications are required.

DINA, “Dynamic networks for trajectory determination in complex environments” (original title in Spanish “Redes Dinámicas para la determinación de trayectorias en entornos complejos”) is a research and development (R&D) project that aims at developing software to demonstrate, in an application relevant environment, the feasibility of trajectory determination with the dynamic network approach for mapping and post-mission trajectory reconstruction.

DINA mainly aims at time-Position-Velocity-Attitude (tPVA) determination with navigation satellite range measurements, inertial measurements and measurements made on “imaging sensor” data, where an “imaging sensor” can be a line, frame camera or a laser scanner. The project, focuses on post-mission processing for optimal precision, accuracy and reliability.

The ATENEA project aimed to integrate GNSS, INS and LiDAR observations to perform precise and accurate navigation and positioning in general outdoor environments, from urban canyons to open areas. The ATENEA approach to navigation and positioning was of particular interest for a wide range of high precision tasks in difficult environments. ATENEA demonstrated the potential of INS/GNSS/LiDAR integration by being rehearsed and tested in the area of kinematic surveying for urban mapping.

Urban mapping with LiDAR techniques -the so-called terrestrial mobile mapping- is already an active domain, but is today only viable using high-end systems with a unitary cost in the order of 800 k€. On the technical level, the orientation of LiDAR instruments and the georeferencing of the scanned objects is provided nowadays by loosely or closely coupled INS/GPS integrated systems, leading to suboptimal performance in urban areas with poor satellite visibility and harsh multipath conditions.

Continue Reading