Navigation In 3D Space Research Articles

Registration of apartments and office spaces in 3D land administration – A case study in Croatia

Due to the needs of modern society, cadastral systems should be designed to support three dimensional (3D) spatial data. One of many possible approaches for implementing a 3D cadastre, in countries such as Croatia, is to establish a Building Register as a transitional register between 2D and 3D cadastres, where data about buildings and infrastructure would be collected, gradually adapted to the data model of 3D cadastre, and finally migrated to the 3D cadastre database. Sources for establishing the Building Register can be based on the records of state surveys, the register of administrative units, the land book, data managed by local and regional self-government units, data from construction documentation according to special regulations in the field of spatial planning, data managed by the building and infrastructure managers, as well as from other sources. A significant element of the 3D cadastre would be the inclusion of representations of buildings and units of use, as well as public utility infrastructure and complex spatial real-life entities (e.g., bridges, tunnels, overpasses, underpasses, overlapping of constructed objects with natural facilities, large shopping malls with more underground and overhead floors etc.). This paper presents a conceptual model of a 3D cadastre in Croatia by establishing the Building Register with focus on unit of use of real properties, namely apartments and office spaces. The paper also summarizes the current situation regarding the Croatian Land Administration System (LAS) and proposes a conceptual model for modelling unit of use of real properties. Additionally, a proposal is made herein to assign unique identifiers to buildings and their parts in a logical manner which would be intuitive and clear to citizens of Croatia, citizens of European Union and citizens of Croatia neighboring countries. The proposed methodology of determining unique identifiers could provide the means for easier navigation in 3D space and better understanding of spatial information by lay citizens, by institutions or emergency services.

Human sperm rotate with a conserved direction during free swimming in four dimensions.

Head rotation in human spermatozoa is essential for different swimming modes and fertilisation, as it links the molecular workings of the flagellar beat with sperm motion in three-dimensional (3D) space over time. Determining the direction of head rotation has been hindered by the symmetry and translucent nature of the sperm head, and by the fast 3D motion driven by the helical flagellar beat. Analysis has been mostly restricted to two-dimensional (2D) single focal plane image analysis, which enables tracking of head centre position but not tracking of head rotation. Despite the conserved helical beating of the human sperm flagellum, human sperm head rotation has been reported to be uni- or bi-directional, and even to intermittently change direction in a given cell. Here, we directly measure the head rotation of freely swimming human sperm using multi-plane 4D (3D+t) microscopy and show that: (1) 2D microscopy is unable to distinguish head rotation direction in human spermatozoa; (2) head rotation direction in non-capacitating and capacitating solutions, for both aqueous and viscous media, is counterclockwise (CCW), as seen from head to tail, in all rotating spermatozoa, regardless of the experimental conditions; and (3) head rotation is suppressed in 36% of spermatozoa swimming in non-capacitating viscous medium, although CCW rotation is recovered after incubation in capacitating conditions within the same viscous medium, possibly unveiling an unexplored aspect of the essential need of capacitation for fertilisation. Our observations show that the CCW head rotation in human sperm is conserved. It constitutes a robust and persistent helical driving mechanism that influences sperm navigation in 3D space over time, and thus is of critical importance in cell motility, propulsion of flagellated microorganisms, sperm motility assessments, human reproduction research, and self-organisation of flagellar beating patterns and swimming in 3D space.

Understanding MPEG-I Coding Standardization in Immersive VR/AR Applications

After decennia of developing leading-edge 2D video compression technologies, the Moving Picture Expert Group (MPEG) is currently working on the new era of coding for immersive applications, referred to as MPEG-I, where “I” refers to the “Immersive” aspects. It ranges from 360° video with head-mounted displays to free navigation in 3D space with head-mounted and 3D light field displays. Two families of coding approaches, covering typical industrial workflows, are currently considered for standardization—MultiView + Depth (MVD) Video Coding and Point Cloud Coding—both supporting high-quality rendering at bitrates of up to a couple of hundreds of megabits per second. This paper provides a technical/historical overview of the acquisition, coding, and rendering technologies considered in the MPEG-I standardization activities.

Laser-Inertial Aided 3D Scanner Using Geometric Invariant for Terrain Construction

Researchers in robotic vision technology are facing larger challenges, where the 2D technology has flaws in complex robot navigation in 3D space. Using 3D scanner, the robot is able to get a more detailed terrain construction, making it easier to carry out its tasks. The 3D image is obtained by fusing the Hokuyo URG-04LX and the 6-DOF IMU that consists of acceleration sensor and gyro sensor. IMU sensor outputs are the angle, speed, and position in 3D. Nevertheless, just the value of the angle is used in this study to construct 3D images based on geometric invariant. To reduce the interference in the sensor output, two types of filter are applied; the Gaussian filter used on the output of 2D LRF, while the complementary filter is applied to the output of the IMU sensor. Angle measurement plays an important role in term of geometric invariant for terrain construction. The complementary filter has provided the best angle measurement results with the lowest error on time constant (τ) = 0.475s and sampling time (dt) = 10ms. Thus, the proposed systems have successfully made an obvious 3D image of the terrain in the indoor testing.

Three-dimensional head-direction coding in the bat brain.

Navigation requires a sense of direction ('compass'), which in mammals is thought to be provided by head-direction cells, neurons that discharge when the animal's head points to a specific azimuth. However, it remains unclear whether a three-dimensional (3D) compass exists in the brain. Here we conducted neural recordings in bats, mammals well-adapted to 3D spatial behaviours, and found head-direction cells tuned to azimuth, pitch or roll, or to conjunctive combinations of 3D angles, in both crawling and flying bats. Head-direction cells were organized along a functional-anatomical gradient in the presubiculum, transitioning from 2D to 3D representations. In inverted bats, the azimuth-tuning of neurons shifted by 180°, suggesting that 3D head direction is represented in azimuth × pitch toroidal coordinates. Consistent with our toroidal model, pitch-cell tuning was unimodal, circular, and continuous within the available 360° of pitch. Taken together, these results demonstrate a 3D head-direction mechanism in mammals, which could support navigation in 3D space.

Interacting in 3D Space: Comparison of a 3D Two-handed Interface to a Keyboard-and-mouse Interface for Medical 3D Image Manipulation

Interacting with computer-generated 3-dimensional (3D) data can pose challenges in the control of 3D objects and navigation in 3D space. The traditional mouse-driven interfaces are limited to controlling two degrees of freedom (DOF) at a time. The current research examines the efficacy of a two-handed interface (THI), “iMedic,” that uses two 6-DOF controllers that afford a more direct style of manipulation of 3D medical imagery. The iMedic interface employs a 3D “multi-touch” type of interaction for manipulation of objects, and self-navigation in space. Medical 3D images of human anatomy from computer tomography (CT) scans were used as a testbed in comparing the two interface: the THI, and a traditional keyboard-and-mouse interface (KMI) commonly used in medical imaging contexts. Novice system users with medical background used each system to carry out navigation, visual search, and measurement tasks with abstract synthetic and realistic anatomical objects. Results indicate that for novice users, there was no clear advantage to either interface in subjective or objective measures. However, a case study of an experienced user showed clear advantages in all tasks using the THI. Reasons for the findings are examined, and interface design implications are discussed.

Interacting in 3D Space: Comparison of a 3D Two-handed Interface to a Keyboard-and-mouse Interface for Medical 3D Image Manipulation

Interacting with computer-generated 3-dimensional (3D) data can pose challenges in the control of 3D objects and navigation in 3D space. The traditional mouse-driven interfaces are limited to controlling two degrees of freedom (DOF) at a time. The current research examines the efficacy of a two-handed interface (THI), “iMedic,” that uses two 6-DOF controllers that afford a more direct style of manipulation of 3D medical imagery. The iMedic interface employs a 3D “multi-touch” type of interaction for manipulation of objects, and self-navigation in space. Medical 3D images of human anatomy from computer tomography (CT) scans were used as a testbed in comparing the two interface: the THI, and a traditional keyboard-and-mouse interface (KMI) commonly used in medical imaging contexts. Novice system users with medical background used each system to carry out navigation, visual search, and measurement tasks with abstract synthetic and realistic anatomical objects. Results indicate that for novice users, there was no clear advantage to either interface in subjective or objective measures. However, a case study of an experienced user showed clear advantages in all tasks using the THI. Reasons for the findings are examined, and interface design implications are discussed.