Understanding the growth and development of individual plants is of central importance in modern agriculture, crop breeding, and crop science. To this end, using 3D data for plant analysis has gained attention over the last years. High-resolution point clouds offer the potential to derive a variety of plant traits, such as plant height, biomass, as well as the number and size of relevant plant organs. Periodically scanning the plants even allows for performing spatio-temporal growth analysis. However, highly accurate 3D point clouds from plants recorded at different growth stages are rare, and acquiring this kind of data is costly. Besides, advanced plant analysis methods from machine learning require annotated training data and thus generate intense manual labor before being able to perform an analysis. To address these issues, we present with this dataset paper a multi-temporal dataset featuring high-resolution registered point clouds of maize and tomato plants, which we manually labeled for computer vision tasks, such as for instance segmentation and 3D reconstruction, providing approximately 260 million labeled 3D points. To highlight the usability of the data and to provide baselines for other researchers, we show a variety of applications ranging from point cloud segmentation to non-rigid registration and surface reconstruction. We believe that our dataset will help to develop new algorithms to advance the research for plant phenotyping, 3D reconstruction, non-rigid registration, and deep learning on raw point clouds. The dataset is freely accessible athttps://www.ipb.uni-bonn.de/data/pheno4d/.

The upcoming European Space Agency (ESA) satellite mission GENESIS is an Earth-orbiting satellite carrying instruments of all four space geodetic techniques. The onboard transmitter for Very Long Baseline Interferometry (VLBI) will allow the observation of the satellite with VLBI radio telescopes. The objective of this study is to investigate the integration of VLBI observations of GENESIS into the operations of the VLBI Global Observing System (VGOS). Based on both current and foreseeable modern VGOS antenna networks, we consider the realistic observability of both geodetic radio sources and GENESIS. We conduct a comprehensive scheduling and perform extensive simulations of the VLBI observations. We assume that observations of GENESIS are scheduled within regular, geodetic experiments. The integration of GENESIS as an additional source in the scheduling results in a minimal degradation in the geodetic parameter estimation of station positions and dUT1 of less than 0.09 mm and 0.06 μs, respectively. The results suggest to schedule scans of GENESIS at intervals of about 5 min to limit the decrease in the number of observations of geodetic sources to less than 5% with respect to schedules containing only geodetic radio sources. The schedules for 24 h experiments comprise about 150 to 200 scans and 1000 to 5000 observations of GENESIS, depending on the size of the utilized network. The frame tie accuracy between the VLBI and GENESIS frames is assessed in the form of station positions, which are solely estimated from observations of GENESIS. Multiple 24 h experiments are simulated over 52 weeks with assumed session cadences of two to three experiments per week. By stacking the normal equations from three months of experiments, we obtain station position estimates with a precision of less than 10 mm. After 12 months, the repeatabilites are reduced to less than 5 mm.

Using the very long baseline interferometry (VLBI) technique to observe Earth-orbiting satellites is a topic of increasing interest for the establishment of frame ties. We present a simulation study on VLBI observations to BeiDou and Galileo satellites in L-band to investigate the accuracy of inter-technique frame ties between VLBI and global navigation satellite system (GNSS). We employ a global network of 16 antennas equipped with dedicated L-band receivers capable of observing BeiDou’s B1 and B3 navigation signals and Galileo’s E1 and E6 navigation signals. Through extensive Monte Carlo simulations, we simulate 24-h sessions to determine the optimal ratio of satellite to quasar scans. The optimal schedule uses about 80–90% satellite sources. We find that the 10–20% observations of quasar sources improve the estimation of the troposphere and, consequently, the estimation of the antenna position. Combining the normal equations from seven 24-h sessions, we derive a 7-day solution. The average antenna position repeatability is 7.3 mm. We identify the limitations of the results as the tropospheric turbulence, inaccuracies in the satellite orbit determination, and the lack of a more homogeneously distributed global network. This simulation study supports the understanding in the topic of building a frame tie using VLBI observations to GNSS satellites.

With the GENESIS proposal accepted, this study reevaluates the implementability of incorporating VLBI observations of satellites into geodetic VLBI experiments. Observations of NavIC system satellites were carried out using the 12-m AuScope radio telescopes in Hobart and Katherine. The primary focus is on scrutinizing the necessary efforts within the VLBI community aimed at effectively supporting the GENESIS satellite mission. Our investigation identifies limitations in the existing processing pipelines, particularly in the generation of station-specific procedure and local control files, as well as in satellite tracking support within the antenna control units, resulting in step-wise tracking rather than continuous tracking. Additionally, we have conducted an analysis to ascertain the effective visibility of the GENESIS satellite within both current and future VLBI networks. Our findings align with the envisioned visibility criteria of GENESIS when more VGOS-type stations are integrated into the current network. In this case, the satellite becomes visible from at least two stations with long baselines for approximately 75.6% of the time during experiments and 21.5% of the time in a year.

This paper introduces a new instrument enabling a novel combination of Earth measuring techniques: direct observations with the radio astronomical instruments to satellites of the global navigation satellite systems (GNSS). Inter-technique biases are a major error source in the terrestrial reference frame. Combining two major space-geodetic techniques, GNSS and Very Long Baseline Interferometry (VLBI), through observations to identical sensors has been considered infeasible due to their seemingly incompatible operating frequencies. The newly accessible L-band capability of the Australian VLBI Global Observing System telescopes is shown here, invalidating this prevailing opinion. A series of test observations demonstrate geodetic VLBI observations to Global Positioning System satellites for a continental-wide IVS telescope array, with the potential for observations at a critical scale. We anticipate immediate impact for the geodetic community, through first-ever inter-technique ties between VLBI and GNSS in the Australian region and via the opportunity for critical test observations toward the Genesis mission, geodesy’s flagship project in the area of space ties set for launch in 2028.

Interest in the topic of geodetic co-location in space and space ties has recently intensified within the geodetic community, particularly following the approval of the European Space Agency’s Genesis mission. From the perspective of very long baseline interferometry (VLBI), observations of Earth-orbiting satellites are not standard practice yet. To enable VLBI support for future co-location satellite missions, such observations must be integrated into the VLBI processing chain. In this study, we present comprehensive VLBI observations of Galileo navigation satellites conducted with the Australian AuScope VLBI array. Using the 12-m antennas in Hobart, Katherine, and Yarragadee equipped with VLBI Global Observing System instrumentation, Galileo E1 and E6 signals were observed in test experiments and a series of four full-scale 24-h observing sessions. We present the estimation of VLBI station coordinates from observations to navigation satellites, thereby demonstrating, for the first time, inter-technique ties between the VLBI and global navigation satellite system (GNSS) frame. We describe the processing strategy, including correlation, fringe fitting, precision assessment, and satellite tracking approach. Delay observables achieve precisions of a few picoseconds in the E1 band and several tens of picoseconds in the E6 band for 1-s integration times. However, unmodelled signals on the order of several hundred picoseconds are found in the residual delays. Estimated station coordinates agree with a priori values at the metre level, while baseline lengths agree at the sub-metre level. These results demonstrate the feasibility of large-scale VLBI observations to GNSS satellites and provide critical groundwork for future co-location satellite missions such as Genesis.