Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Photogrammetry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1979

[Comparative clinical and photogrammetric studies on the marginal periodontium after the use of dentifrices].

A suggestion was made for testing the therapeutic effect of certain substances on gingival inflammation. Gingivitis was induced in 60 subjects by discontinuing of all forms of oral hygiene. Three tooth pastes, one of which was a placebo, were used for the study. Regression of the inflammation was determined with the periodontal indexes and photogrammetry. Photogrammetry appears to be well suited for objective evaluation of the therapeutic value of certain substances.

Dental Plaque↗
PubMed1986

[Optical methods in the study of superficial displacements of the lumbar vertebrae under a vertical load. Initial results and methodological aspects].

In order to assess superficial displacements under load in human lumbar vertebrae, the authors used three different optical methods: photogrammetry under non coherent light; double-exposure holographic interferometry; speckle granularity under laser exposure. Without any structural interposition, the displacements are measured within 10 mu for linear variations and 0.1 degrees for angular variations. Photogrammetry seems to be more adequate for the study of large range of displacements while holographic and speckle techniques are useful to assess, in the displacements, the part of the disc and the osseous structure deformation respectively.

Biomechanical Phenomena↗
PubMed1996

Three-dimensional facial morphometry and conventional cephalometrics: a correlation study.

The purpose of this study was to compare the correlation between three-dimensional soft tissue measurements obtained with three-dimensional digital infrared photogrammetry and two-dimensional data obtained with conventional cephalometry. Facial morphometry was investigated in a group of 20 healthy young men using both systems on each subject. From the lateral radiographs, conventional two-dimensional cephalometric hard and soft tissue data were calculated, while three-dimensional linear and angular soft tissue measurements were computed from the infrared photogrammetry. The correlations between the two sets of measurements were calculated. Three-dimensional soft tissue measurements correlated to cephalometric data primarily contained information useful for esthetic analysis. The soft tissue infrared measurements also allowed evaluation of the general hard tissue situation. Since the soft tissue measurements are calculated with a noninvasive system, they could be computed more frequently during treatment and be used to supplement pretreatment and posttreatment radiographs.

Adult↗
PubMed2002

[3-dimensional image acquisition for analysis of primary, cleft-induced facial deformity with an optoelectronic surface scanner].

BACKGROUND: Anthropometric analysis of the face has been performed with direct facial measurement and photogrammetry. Both methods have disadvantages. The aim of our investigation was to create a three-dimensional image of the primary cleft nasal deformity with a video scanner and to carry out linear measurements. MATERIAL AND METHODS: Facial plaster casts of 19 patients with uni- and bilateral cleft lip and palate before primary lip repair were scanned with digital surface photogrammetry DSP 400. The width of the nose and of the nostril floor, the distance of the alar bases, the length of the ala, and the nasal tip protrusion were measured. RESULTS: Imaging was possible without problems in all models. Direct measurements of the model correlated well with the results of the three-dimensional image. Significant dimensional differences of the nasal parameters examined were noted, depending on the cleft type. DISCUSSION: A video-supported surface scanner allowed immediate three-dimensional imaging of the face. The computer software analyzed the generated surface exactly. The data measured with the presented system resembled other previously published results.

Casts, Surgical↗
PubMed1989

A three-dimensional musculoskeletal model for gait analysis. Anatomical variability estimates.

Three-dimensional coordinates defining the origin and insertion of 40 muscle units, and bony landmarks for osteometric scaling were identified on dry bone specimens. Interspecimen coordinate differences along the anterior-posterior axis of the pelvis and the long bone axes of the pelvis, femur and leg were reduced by scaling but landmark differences along the other axes were not. The coordinates were mapped to living subjects using close-range photogrammetry to locate superficial reference markers. The error of predicting the positions of internal coordinates was assessed by comparing joint centre locations calculated from local axes defining the orientation of segments superior and inferior to a joint. A difference was attributed to: anatomical variability not accounted for by scaling; errors in identifying and placing reference landmarks; the accuracy of locating markers using photogrammetry and error introduced by marker oscillation during movement. Anatomical differences between specimens are one source of error in defining a musculoskeletal model but larger errors are introduced when such models are mapped to living subjects.

Anthropometry↗
PubMed2002

The use of Roentgenstereofluorogrammetry to predict the 3-D spatial coordinates of points in low speed events.

Imaging technologies such as cine-radiography, cine-MRI, and X-ray stereo photogrammetry have become popular diagnostic tools in biomechanical studies of musculoskeletal systems. However, their widespread use for research purposes has been restricted due to their high cost and somewhat limited availability. In an attempt to develop a reliable low cost system, a dual-fluoroscopic system capable of tracking the 3-D spatial motion of discrete landmark points in real time was developed. A simple methodology was developed to convert the analog fluoroscopic images to digital files for post-processing. A custom computer code based on the principles of X-ray stereo photogrammetry was also developed to predict 3-D coordinates from the 2-D images from the individual flouroscopes. The goal of the current study was to assess the accuracy and resolution of this system by using it to predict the motion of a test point following a known curvilinear trajectory. Our system predicted the time-varying motion and path of the test point within 0.25%. However, the current system is limited to studying low speed events only (max event frequency of 3Hz) due to the limited sampling frequency of the A/D conversion employed here.

Biomechanical Phenomena↗
PubMed1997

Comparison of hip center estimation using in-vivo and ex-vivo measurements from the same subject.

OBJECTIVE: To evaluate the accuracy of locating the hip center (HIPC) by comparing in-vivo estimations to posthumous HIPC measurement in the same subject. BACKGROUND: Numerous techniques have been used to locate the HIPC in living subjects and in cadavers. There are no published reports, however, which have compared measurements of the HIPC obtained in-vivo and ex-vivo for the same subject. DESIGN AND METHODS: Bilateral hip centers (HIPC) were estimated for an elderly male patient seven times over 32 months in a gait laboratory using a technique which combines kinematic data and static pointing. The patient's pelvis was recovered posthumously and analytical photogrammetry used to estimate the HIPC locations. Published methods which scale anatomical measurements to locate the HIPC were compared to our ex-vivo and in-vivo measurements. RESULTS: HIPC precision was 0.94 cm for the in-vivo measurements (N = 7 trial days) and 0.15 cm for the ex-vivo measurements (N = 6 photogrammetry trials). The resultant error between ex-vivo and in-vivo estimates of HIPC position was 1.17 cm. Resultant errors in locating the HIPC using published anatomical scaling factors ranged between 1.48 cm and 5.37 cm. CONCLUSIONS: Although we have been unable to compare in-vivo and ex-vivo HIPC measurements for more than one subject, results of our analysis suggest that using anatomical scaling to locate the HIPC may result in unsatisfactory subject-specific estimates of the HIPC.

Journal Article↗
PubMed2004

Tri-dimensional morphometric analysis of astrocytic processes with high voltage electron microscopy of thick Golgi preparations.

A characteristic feature of the astrocytic processes is to assume the form of shin sheets or lamellate coverings of other brain constituents. We analyzed the extensive and finely divided processes of the protoplasmic astrocyte in the molecular layer of the rat dentate gyrus by means of computer electron tomography and stereo-photogrammetry using tilted high voltage electron microscope images of thick Golgi preparations. The surface area and volume of the astrocytic processes were measured and the surface/volume ratios were estimated. The surface/volume ratios of astrocytic processes in the neuropile ranged from 18.9 to 33.0 per microm, and the mean value was 26.2+/-5.0 per microm. The values were roughly comparable to those previously reported for the microdomain of Bergmann glia cell terminal processes in the rat cerebellum, which were estimated from reconstructions using thin serial section electron microscope images. The large surface to volume ratio of the astrocytic processes in the neuropile resulted from the lamellar nature of the processes interposed between other cellular elements, and may reflect the functional activities of the astrocyte. The results suggest the usefulness of the electron tomography and stereo-photogrammetry for three-dimensional morphometrical analysis of the astrocytic processes, although both techniques can be expected to be refined further in order to provide more precise measurements of these complicated processes.

Animals↗
PubMed1993

Accuracy of the PAR corneal topography system with spatial misalignment.

The PAR Corneal Topography System is a computerized corneal imaging system which uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. Raster photogrammetry is a standard method of extracting object information by projecting a known pattern onto an object and recording the distortion when viewed from an oblique angle. Unlike placido disc based videokeratoscopes, the PAR system requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. We studied both the accuracy of the system with purposeful misalignment (defocusing) of the test object and determined the ability to image freshly deepithelialized, keratectomized, and photoablated corneas. The PAR system was both accurate and reproducible in imaging calibrated spheres within a defined zone in space. Whole cadaver eyes were imaged both before and immediately after removal of the epithelium, lamellar keratectomy, and laser photoablation. The system demonstrated the ability to image irregular, deepithelialized, and keratectomized corneas. The ability to maintain accuracy without precise alignment and the facility to image freshly deepithelialized and keratectomized corneas may make the system suitable for intraoperative refractive monitoring.

Cornea↗
PubMedDate not supplied

Experimental study on external tibial rotation of the knee.

Using biplanar roentgenographic photogrammetry, we investigated posterolateral rotatory instability of the knee joint both before and after sectioning of posterolateral structures, the posterior cruciate ligament, and the lateral collateral ligament. Fifteen fresh-frozen cadaveric knees were used. Compared with the intact state, sectioning of the posterior cruciate ligament alone did not increase the amount of external tibial rotation, but the axis of external tibial rotation shifted when the anterolateral bundle of the posterior cruciate ligament was cut. When the posterior cruciate ligament was cut after sectioning of the posterolateral structures and the lateral collateral ligament, external tibial rotation increased and the axis of external rotation shifted. The results demonstrated that sectioning of the anterolateral bundle of the posterior cruciate ligament is associated with a change in the location of the axis of tibial rotation. Therefore an isolated posterior cruciate ligament injury can alter the kinematics of the knee joint by changing the axis of external tibial rotation. The present results also demonstrate that the posterior cruciate ligament serves as a kind of secondary restraint to posterolateral rotatory instability in knees with injured posterolateral structures. Helical motion analysis using biplanar roentgenographic photogrammetry is a useful method for evaluating knee kinematics.

Aged↗
PubMed1980

Stereochronoscopy of the optic disc with stereoscopic cameras.

Goldmann's chronoscopy, a form of time-based photogrammetry of the optic disc, can be accomplished by repeated simultaneous stereophotography. The variations in centration and image orientation are nulled by azimuthal rotation and fusion of two pairs of stereophotographs taken at separate times.

Humans↗
PubMed1989

Malar augmentation. Patient classification and placement.

Aesthetic malar augmentation is described to improve the appearance of patients with flattening of the malar eminence, to create a more youthful appearance of the face, to make the face more oval in appearance, and to de-emphasize prominent nasal or mental profiles. Detailed preoperative analysis of surgical candidates has not been reported. Twenty models studied by photogrammetry of frontal, lateral, and oblique views were analyzed to synthesize ideal measurements of an aesthetic face with particular attention to points describing the malar mound. Photographs of patients operated on were analyzed using computer graphics to compare the synthesized ideal and surgical results. Ideal candidates are defined as those patients with ptotic malar mounds with adequate soft tissue to create a balanced and harmonious result. Examples of candidates and potential pitfalls are presented.

Adult↗
PubMed2005

Precision and error of three-dimensional phenotypic measures acquired from 3dMD photogrammetric images.

The genetic basis for complex phenotypes is currently of great interest for both clinical investigators and basic scientists. In order to acquire a thorough understanding of the translation from genotype to phenotype, highly precise measures of phenotypic variation are required. New technologies, such as 3D photogrammetry are being implemented in phenotypic studies due to their ability to collect data rapidly and non-invasively. Before these systems can be broadly implemented, the error associated with data collected from images acquired using these technologies must be assessed. This study investigates the precision, error, and repeatability associated with anthropometric landmark coordinate data collected from 3D digital photogrammetric images acquired with the 3dMDface System. Precision, error due to the imaging system, error due to digitization of the images, and repeatability are assessed in a sample of children and adults (n = 15). Results show that data collected from images with the 3dMDface System are highly repeatable and precise. The average error associated with the placement of landmarks is sub-millimeter; both the error due to digitization and due to the imaging system are very low. The few measures showing a higher degree of error include those crossing the labial fissure, which are influenced by even subtle movement of the mandible. These results suggest that 3D anthropometric data collected using the 3dMDface System are highly reliable and, therefore, useful for evaluation of clinical dysmorphology and surgery, analyses of genotype-phenotype correlations, and inheritance of complex phenotypes.

Adult↗
PubMed1987

Surface strain on human intervertebral discs.

The biomechanical functions of the internal components of the intervertebral disc are not well understood. The surface deformation of 17 human cadaveric lumbar intervertebral discs was studied by photogrammetry by adhering small optical targets to the disc surface and thereby recording the length, bulge, and vertical height of lines on the disc surface representing annular fibers. Discs were studied in pure compression, flexion and extension, axial rotation, and shear. Two definitions of a fiber were investigated: first with the end-points of the fiber on the vertebra ("bone-to-bone" definition), second, where the end points of the fiber were just before the disc vertebra junction (the "disc-only" definition). Measurements were compared with a "constant-volume" physical model and with a mathematical model of the intervertebral disc. Fiber strains were 6% or less under physiological conditions. Comparison of results from the two definitions of fiber length showed greater strains for the disc-only definition in compressive loading. Fiber strains were less than in the constant-volume model of comparable dimensions in compressive loading by a factor of about two, thus suggesting fluid loss or end-plate deformations in the physiologic conditions. The mathematical model indicated that the surface strain for intervertebral discs is very sensitive to the disc-height: diameter ratio and to fluid loss from the disc but is less sensitive to the helix angle of the fibers.

Adult↗
PubMed1996

Digital photogrammetric quantification of surface area and volume on scanning electron micrographs of frozen hydrated lung tissue.

A digital video plotter (DVP, Leica), the personal computer equivalent of an analytical plotter, was used to measure the coordinates of points chosen from stereo pair images of the surface of frozen hydrated lung imaged at magnifications of 2000 and 5000 X with a low-temperature scanning electron microscope (SEM). Rat lung tissue was frozen in vivo with a liquid nitrogen cryoprobe under carefully controlled physiologic conditions. At slow freezing rates, water in the aqueous layer at the surface of the lung segregates into ice crystals (dendrites) which branch in the plane of the surface. Coordinates of points on dendrite surfaces were measured by the DVP and passed to TERRAMODEL (Plus III Software, a land modeling program) where they were used to generate a three-dimensional model, from which surface area and planimetric area of the lung surface were calculated. Additional measurements were made at the top and bottom of the ice structures and a Basic language program was written to calculate the volume of ice on the lung surface. Digital photogrammetry coupled with low-temperature SEM of frozen samples allows measurement of water and water-containing microstructures ubiquitous in biology.

Animals↗
PubMed1996

[Changes in abdominal wall mechanics after mesh implantation. Experimental changes in mesh stability].

The use of biomaterials for incisional hernia markedly reduces the recurrence rates. Disadvantages are high rates of local wound complications and restriction of mobility by the rigid "shell". The abdominal wall mobility after mesh implantation is analysed for eight different mesh materials. The initial textile testing reveals relevant differences in structure with marked asymmetry in the different directions. The materials are implanted as inlay in rats for 3, 7, 14, 21 and 90 days. The deformation of the abdominal wall following intraabdominal pressure of 0-70 mmHg (0-9.81 kPa) is documented by 3D-photogrammetry, the tensile strength by tearing of excised strips of mesh. Three commercial available materials and two laboratory modifications lead independently of their textile characteristics to a marked restriction of the rounded configuration of the abdominal wall. The tensile strength exceeds by far the physiologically necessary value of 16 N/cm. Three newly developed meshes made of multifilament polypropylene with reduced amounts of material (21% and 28% relative to Marlex) lead to no restriction of the abdominal wall configuration yet have uncompromised stability. It might be possible to reduce the rate of local wound complications by the use of these newly developed meshes.

Abdominal Muscles↗
PubMed1984

Mathematical kinematics in engineering of endoprostheses. Evaluation of the results of gait analysis.

Certain optical methods (photogrammetry) achieve great precision in analysis of body motion. However, this study clearly shows that the tracing of body surface movement is unsuitable for analysis of actual joint motion, at least in the knee joint, because of the soft tissue shifting which occurs. It is also shown that comparatively simple mathematical-kinematic techniques can be used to check the degree of error of methods of measurement in orthopedics. It is to be assumed that no currently available knee joint prostheses function in a kinematically perfect manner. If the movement of knee joint prostheses is to be optimized and implantation errors affecting kinematics avoided, it seems indispensable, at the current level of technology, to employ X-ray stereophotogrammetry to describe natural knee joint motion.

Biomechanical Phenomena↗
PubMed2002

Contactless measurement of canine retraction by digital macrophotogrammetry during hybrid retractor application.

A new contactless method for measuring tooth movements is presented. Digital macrophotogrammetry (DMP) enables the orthodontist to obtain information on the three-dimensional movement of a tooth at each session. Analysis of the DMP images provides information on the translation and toration of a tooth during treatment. It is conceivable that the introduction of DMP will make an important contribution to quality assurance.DMP application during canine retraction with the Hybrid Retractor((R)) has pave the way for the orthodontic appliance to be correctly adjusted at each session. Despite intra- and interindividual differences during canine movement, for which the anisotropy of the bone seems to be basically responsible, a movement velocity of ca 1.2 mm is to be expected over the entire treatment period. The preconditions for the three-dimensional orientation and description of canine movement are:1. The markers on the brackets and attachments must be clearly visible throughout the treatment.2. The teeth to which the scaling frame is fixed should not move during treatment.3. Four measuring points should be visible on each bracket.4. The control points on the frame must be positioned three-dimensionally, and it must be possible to determine their position with sufficient accuracy in advance. In vitro calibration of the photogrammetry presented here yielded a resolution of 1 micrometer for translation and of better than 1/10 degrees for rotation around the three spatial axes under optimal conditions.

Cuspid↗