Photographic Positions Research Articles

A METHOD FOR MEASURING LARGE-SCALE DEFORMATION OF LANDSLIDE BODIES BASED ON NAP-OF-THE-OBJECT PHOTOGRAMMETRY

Abstract. Geological disasters such as landslides and debris flows pose a serious threat to human life and property. To mitigate this risk, monitoring and early warning systems are essential. However, monitoring high-angle landslide areas can be challenging due to the steep and complex terrain, making it difficult to carry out large-scale and refined deformation measurements using existing methods. This paper proposes a method to measure the large-scale deformation of landslide bodies based on nap-of-the-object photogrammetry. The method uses UAVs to acquire high-resolution 3D models of steep and high landslide areas at multiple time periods. Then, 3D model matching is employed to obtain accurate variation information for terrain deformation measurement. To obtain fine 3D models, a terrain-adaptive nap-of-the-object photogrammetric flight planning is applied to design the optimal photographic positions and directions for capturing ultra-high-resolution images. The images are processed using photogrammetric principles and technologies to produce fine 3D models. For terrain deformation measurement, an algorithm is proposed to obtain 3D correspondences by fusing DEM differential and 3D model texture matching. The 3D points variation vectors are then calculated, and the large-scale deformation measurement results of the landslide body can be derived after the vectors are aggregated. Experiments were conducted on the Lijiebeishan landslide in Gansu Province, western China. The results showed that the proposed deformation measurement method was highly effective in accurately detecting areas with displacement greater than 5 cm, and the large-scale deformation trend is consistent with GNSS predictions. In conclusion, the proposed method is an effective way to measure the large-scale deformation of landslide bodies in high-angle landslide areas, providing a valuable tool for monitoring and early warning systems.

Modelling and Repeating Early Photographic Positions with Aerial Drones

Modelling and Repeating Early Photographic Positions with Aerial Drones

Mathematically optimized trajectory for terrestrial close-range photogrammetric 3D reconstruction of forest stands

Terrestrial close-range photogrammetry offers a low-cost method of three-dimensional (3D) reconstruction of forest stands that provides automatically processable 3D data that can be used to evaluate inventory parameters of forest stands and individual trees. However, fundamental methodological problems in image acquisition and processing remain. This study enhances the methodology of photogrammetric Structure from Motion reconstruction of forest stands by determining the best photographer's trajectory for image acquisition. The study comprises 1) mathematical optimization of the route in a square grid using integer programming, 2) evaluation of point clouds derived from sequences of real photographs, simulating different trajectories, and 3) verification on real trajectories. In a forest research plot, we established a 1 m square grid of 625 (i.e., 25 × 25) photographic positions, and at each position, we captured 16 photographs in uniformly spaced directions. We adopted real tree positions and diameters, and the coordinates of the photographic positions, including orientation angles of captured images, were recorded. We then formulated an integer programming optimization model to find the most efficient trajectory that provided coverage of all sides of all trees with sufficient counts of images. Subsequently, we used the 10,000 captured images to produce image subsets simulating image sequences acquired during the photographer's movement along 84 different systematic trajectories of seven patterns based on either parallel lines or concentric orbits. 3D point clouds derived from the simulated image sequences were evaluated for their suitability for automatic tree detection and estimation of diameters at breast height. The results of the integer programming model indicated that the optimal trajectory consisted of parallel line segments if the camera is pointed forward – in the travel direction, or concentric orbits if the camera is pointed to a side – perpendicular to the travel direction. With point clouds derived from the images of the simulated trajectories, the best diameter estimates on automatically detected trees were achieved with trajectories consisting of parallel lines in two perpendicular directions where each line was passed in both opposite directions. For efficient image acquisition, resulting in point clouds of reasonable quality with low counts of images, a trajectory consisting of concentric orbits, including the plot perimeter with the camera pointed towards the plot center, proved to be the best. Results of simulated trajectories were verified with the photogrammetric reconstruction of the forest stand based on real trajectories for six patterns. The mathematical optimization was consistent with the results of the experiment, which indicated that mathematical optimization may represent a valid tool for planning trajectories for photogrammetric 3D reconstruction of scenes in general.

Landform monitoring in active volcano by UAV and SfM-MVS technique

Abstract. Nishinoshima volcano in Ogasawara Islands has erupted since November, 2013. This volcanic eruption formed and enlarged a new island, and fused the new island with the old Nishinoshima Island. We performed automated aerial photographing using an Unmanned Aerial Vehicle (UAV) over the joined Nishinoshima Island on March 22 and July 4, 2014. We produced ortho-mosaic photos and digital elevation model (DEM) data by new photogrammetry software with computer vision technique, i.e. Structure from Motion (SfM) for estimating the photographic position of the camera and Multi-view Stereo (MVS) for generating the 3-D model. We also estimated the area and volume of the new island via analysis of ortho-mosaic photo and DEM data. Transition of volume estimated from the UAV photographing and other photographing shows the volcanic activity still keeps from initial level. The ortho-mosaic photos and DEM data were utilized to create an aerial photo interpretation map and a 3-D map. These operations revealed new knowledge and problems to be solved on the photographing and analysis using UAV and new techniques as this was first case in some respects.

Localization of ectopic maxillary canines — is CBCT more accurate than conventional horizontal or vertical parallax?

To compare the accuracy of cone-beam CT (CBCT) with conventional horizontal and vertical parallax for the localization of ectopic maxillary canines. Observational study. A typodont was constructed using human teeth embedded in radio-dense impression material, containing a simulated ectopic canine. Image sets (vertical/horizontal parallax and CBCT scans) were obtained for nine positions. A photograph confirmed the true position of the canine. Six observers used horizontal (HP) and vertical (VP) parallax techniques with conventional radiographs and the axial, coronal and sagittal CBCT views to locate the canine tip. Images were manipulated as required using proprietary software (http://www.carestream.com and http://www.i-cat.com). Intra-observer reproducibility was calculated by one observer re-evaluating the image sets after 2 months. Individual observer validity was calculated in relation to the photographic position of the canine using weighted Kappa. Differences in the proportion of correct locations between CBCT and vertical/horizontal parallax were tested using McNemar tests (P<0·05). Intra- and inter-observer agreements were excellent (0·8985) and substantial (0·7528), respectively. Individual observer validity was substantial-excellent (0·7368-0·900). The canine position was correctly identified in 94% of cases located using CBCT, 83% using HP and 65% using VP. The differences between CBCT and vertical and horizontal parallax were highly statistically significant (P<0·01). CBCT is more accurate than either horizontal or vertical parallax for the localization of ectopic maxillary canine teeth.

Dynamical study of the wide visual binary ADS 12815 (16 Cyg)

A homogeneous series of photographic position measurments of the visual binary ADS 12815 obtained on the 26-inch refractor of the Pulkovo Observatory (1960–2007) is analyzed. The Pulkovo observations allow for the existence of the planet around component B discovered by Cochran et al. based on radial-velocity measurements. The orbit of the planet must be steeply inclined to the plane of the sky (i ≥ 70°). Uniform series of position measurements obtained at the Dearborn Observatory, US Naval Observatory, and Pulkovo Observatory, the HIPPARCOS parallax, and the relative radial velocities obtained by Hauser and Marcy at the Lick Observatory are used to calculate the elements of possible orbits for the ADS 12815 stars using the apparent motion parameters method. The corresponding periods are more than 20 000 yr, the semi-major axes more than 900 AU, and the eccentricities more than 0.65. All possible orbits are steeply inclined to the Galactic plane. The obtained family of orbits is in better agreement with observations than the family calculated by Hauser and Marcy.

Current state and development of the minor planets research in Nikolaev Astronomical Observatory

Regular positional observations of minor planets in Nikolaev Astronomical Observatory have been begun with installation of photographic Zone Astrograph in 1961. The observations of 19 selected minor planets up to 12 magnitude were obtained for 36 years. Accuracy of the photographic positions of minor planets is rather high, 0 . 15 ′ ′ – 0 . 19 ′ ′ . These positions were used for improvement of the system of fundamental catalogue and determination of its orientation to the dynamical reference frame. CCD observations of asteroids have been begun at the Zone Astrograph in 2000. There was obtained about the same accuracy, as in photographic observations. During 2004–2006 NAO participated in international collaboration with TUBITAK National Observatory (Turkey) and Kazan State University (Russia) in positional and photometric observations of small Solar system bodies. About four thousands of CCD images for 58 asteroids of 11–18 mag were obtained with internal and external errors of 30–80 mas of a single determination. Some of these observations, as well as the observations of the Minor Planet Center, are being used for the current asteroid mass determinations in Nikolaev observatory. Available results allow us to consider the Russian–Turkish telescope RTT150 as a good candidate for ground-based astrometry support of the future space mission GAIA, moreover in the period before GAIA.

Photographic observations of solar system bodies at the Engelhardt astronomical observatory

We describe a large database of photographic observations of Solar System bodies obtained at the Engelhadt Astronomical Observatory (EnAO). We give a brief description of the methods of observations and the accuracy of their reduction with the PPM and Tycho-2 catalogues. The photographic positions of the major planets, except Jupiter, are in the system of the Tycho-2 catalogue and their comparison with DE200 ephemeris coordinates are given.

Measurement of the profile angle and the aesthetic analysis of the facial profile.

Cephalometric measurement of the face in terms of aesthetics can be difficult and misleading due to the variability of the intra-cranial reference lines. Extra-cranial references are more accurate, but can be time-consuming to apply. The Aesthetic Horizontal is an intuitive datum line related to the 'photographic position' of the head, which is expedient in use and clinically relevant. A new and straightforward technique is presented for transferring the Aesthetic Horizontal directly from the patient to any recent radiograph, which can then be used as the reference line for an aesthetic analysis of the facial profile. The instrument used for measuring the profile angle and the transfer is readily constructed from a protractor and small weight. The technique can also be used to transfer any other orientation (e.g. Natural Head Position or Natural Head Posture) from the patient to a recent radiograph.

Astrometric photographic observations of Helene

Astrometric photographic positions of the Saturnian satellite Helene obtained from 22 plates taken in 6 nights are presented. The observations are distributed between 5 missions in 1985 and 1987. All positions are compared with those calculated by Jacobson (1999). The residuals have mean and standard deviation smaller than and respectively.

Working Group on Satellites: (Groupe de Travail Pour Satellites)

During the period from July 1996 to Dec 1998, 189 photographic positions of the galilean satellites were obtained with the zonal astrograph (D=120 mm, F=2044mm). In the year 1998 the close approach of the satellite system with the star N 117881 from the HIPPARCOS catalogue was observed. The observations of 1996 were processed using PPM catalogue and the observations of 1997, 1998 in the ICRS using HIPPARCOS and ACTRC star catalogues. The results are not yet published, but are available upon request. Observations made since 1962 up to 1996 with the zonal astrograph were reprocessed and results are in preparation for publication. During the period from 1996 to 1998, 69 positions of the Galilean satellites were determined by photoelectric meridian observations with the Repsold meridian circle equipped by CCD-microscopes (F=2150 mm, D=150 mm).

Photographic positions for the first eight satellites of Saturn

Astrometric positions of the rst eight Saturnian satellites obtained from 138 photographic plates taken in 30 nights in the years 1982 to 1988 are presented. All positions are compared with those calculated by the theory TASS1.7 (Vienne & Duriez 1998). The observed minus calculated residuals give rise to standard deviations smaller than 0: 00 3.

Photographic observations of Pluto 1991-1994 with the Baldone Schmidt telescope

photographic positions of the Pluto for 1991-1994 are presented. The observations were carried out by Latvian astronomers using the 80/120/240 cm Schmidt telescope at Baldone near Riga. 34 plates were reduced by using the 12-21 reference stars from catalogue of southern stars FOCAT-S, created at Pulkovo. The mean reduction errors vary from 0.23 00 to 0.34 00 for both coordinates. The obtained Pluto positions were compared with the ephemeris JPL DE200. The increase of the mean (O-C) residuals in RA, already noticed in previous works by the Pulkovo authors, is conrmed. In 1994 the (O-C) residuals with respect DE200 have reached 2.32 00 0.07 00 in RA and 0.74 00 0.07 00 in Dec.

New constants for Sampson-Lieske theory of the Galilean satellites of Jupiter from mutual occultation data

New constants for Sampson-Lieske theory of the Galilean Satellites have been derived using 6360 individual photographic positions (1891–1990) and 438 pseudo astrometric positions from mutual occultations during 1973, 1979, 1985 and 1991. Using these new sets of constants, significant improvement is noticed in the O-C values of the sky plane coordinates of the mutual event data set and residuals in longitude for Io and Europa are found to improve. Problems concerning the inclusion of mutual event data in attempting evaluation of secular variations of the mean motions of the satellites are discussed.

The Hipparcos Extragalactic Link

In conformity with the IAU resolutions on reference frames adopted in 1991, the Hipparcos catalogue will represent, in the visible spectrum, the celestial reference system defined by fixed positions of extra-galactic radio-sources. This will be realized by the strongest possible link between the IERS celestial reference frame with positions and/or proper motions of the largest possible number of Hipparcos stars determined also with respect to extragalactic objects. The data which will be used must be available before April 1995. It will include the following: positions and proper motions of radio stars observed by VLBI, VLA and MERLIN; photographic positions in fields including quasars; proper motions with respect to galaxies of the Lick, Yale, and Kiev programs, proper motions derived from pairs of photographic plates taken at large time intervals; and possibly data acquired by Hubble Space Telescope and from Earth's rotation data. The organization of the tasks within the working group is briefly described. The final accuracy of the link is expected to be of the order of, or better than, half a milliarcsecond.

Pluto: An analysis of photographic positions obtained with the pulkovo normal astrograph in 1930–1992

Abstract Results of photographic positional observations of Pluto with the Pulkovo Normal Astrograph (NA, 33/346), made in 1930-1992 and reduced to the system FK5 J2000.0, are presented. All the positions of Pluto observed are compared with the ephemerides JPL DE200. The mean residuals (O - C) in R. A. and Decl. for the middle epochs of observations are given. It is shown that in 1989-1992 the residuals (O - C). reached 2.24 ÷ 2.51 arcsec and keep tendency to further growing. The comparison between the averaged values (O - C)α obtained from observations with different telescopes in 1989-1992 is made, and the existence of a well pronounced trend found in earlier work is confirmed. The spectral analysis of the sets of positional and photometric observations of Pluto detected in (O - C)α and (O - C)δ at the 95 percent confidence the harmonics with amplitudes 0.16 ± 0.04 arcsec, 0.27 ± 0.05 arcsec, and periods 2.11 ± 0.02 yr, 16.5 ± 0.05 yr, respectively. The periodic component with amplitude 0m.16 ± 0m. 04 and period 7.88 ± 0.26 yr is confirmed from analysis of Pluto's light curve for 1954–1990. Possible explanations of the trend and the periodicities found are discussed.

Photographic positions of Minor Planets

AbstractPhotographic precise positions of 16 minor planets obtained with the G.P.O. astrograph at E.S.O. (La Silla ‐ Chile) in January 1988 are given.

Photographic positions of Minor Planets

AbstractPhotographic precise positions of 16 minor planets obtained with the G.P.O. astrograph at ESO (La Silla, Chile) are given.

Photographic positions of Minor Planets

AbstractPhotographic precise positions of 13 minor planets obtained with the G.P.O. astrograph at E.S.O. (La Silla, Chile) in September 1987 are given.

Photographic positions of Minor Planets

AbstractPhotographic precise positions of minor planets, obtained with the G.P.O. astrograph at ESO (La Silla ‐ Chile) and with the ZEN astrograph at Merate, are given