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At least 127 records · Page 7Linked to original sources
PubMed1992

The computer synthesis of expressive faces.

This paper presents a methodology for the computer synthesis of realistic faces capable of expressive articulations. A sophisticated three-dimensional model of the human face is developed that incorporates a physical model of facial tissue with an anatomical model of facial muscles. The tissue and muscle models are generic, in that their structures are independent of specific facial geometries. To synthesize specific faces, these models are automatically mapped onto geometrically accurate polygonal facial representations constructed by photogrammetry of stereo facial images or by non-uniform meshing of detailed facial topographies acquired by using range sensors. The methodology offers superior realism by utilizing physical modelling to emulate complex tissue deformations in response to coordinated facial muscle activity. To provide realistic muscle actions to the face model, a performance driven animation technique is developed which estimates the dynamic contractions of a performer's facial muscles from video imagery.

Computer Graphics↗
PubMed1995

Decrease of optic disc cupping and pallor of ocular hypertensives with timolol therapy.

PURPOSE: The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on optic disc cupping and pallor in ocular hypertensives. METHODS: Thirty-seven ocular hypertensives were randomly assigned to placebo or 0.5% timolol drops to both eyes in a double masked clinical trial. Measurements of ocular pressure and photographs of the optic disc for cupping by photogrammetry and pallor by computerized image analysis were made at about 3 month intervals, for 18 to 24 months of follow-up. RESULTS: None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with timolol developed a significant decrease in ocular pressure and a significant decrease in optic disc cupping with a smaller decrease in pallor compared to subject treated with placebo. Multivariate analyses indicated that the decrease of optic disc cupping and pallor was not associated with the ocular pressure on treatment or the decrease in ocular pressure during the trial. CONCLUSION: Timolol treatment was associated with a decrease in optic disc cupping and pallor. The effect of timolol appears to be related to mechanisms other than the decrease in ocular pressure.

Double-Blind Method↗
PubMed1976

The effect of oral physiotherapy on dilantin gingival hyperplasia.

Gingival hyperplasia was studied in 13 boys with epilepsy living in a state hospital. Boys were selected on the basis of having gingival hyperplasia, having all teeth between cuspids (upper and lower), having no occlusal abnormality and being cooperative. After gingivectomy, regrowth of gingiva was compared around lateral incisors on one side of the mouth having operator-assisted oral hygiene with that around lateral incisors on the other side of the mouth without operator-assisted oral hygiene. Regrowth of tissue was documented by precise photogrammetry. Oral hygiene, gingival inflammation and crevicular fluid were monitored. Less inflammation, less crevicular fluid and less regrowth of gingival tissues occurred around teeth subjected to good oral hygiene. Precise periodic photographic documentation of the clinical status of patients during studies such as this is considered very valuable.

Adolescent↗
PubMedDate not supplied

The PAR Technology Corneal Topography System.

BACKGROUND: Computer-assisted videokeratography has emerged as a useful clinical and research tool. All of the currently available commercial units utilize a modified placido disk image and require a smooth reflective surface. The PAR Technology Corneal Topography System (PAR CTS) is a prototype of a new computer-assisted corneal imaging device. The system produces a true topographic map (elevation map) by analyzing a projected grid on the corneal surface, as opposed to a placido disk reflection, and utilizes the technique of raster photogrammetry to define elevation points on the corneal surface. Because the system defines elevation points, not curvature, mathematical modeling is easily accomplished. Current software displays include a true topographic map, a spherical subtraction map in both relative and absolute scales, and a meridian analysis that is adapted to display refractive photoablative surgery. METHODS: We evaluated the accuracy of this device by analyzing three calibrated test spheres (55.76, 42.21, and 33.55 diopters). The test spheres were steel balls coated with a thin white silicone polyester coating that was necessary for grid projection. The test spheres were measured by a Taylor-Hobson contact profilometer possessing submicron accuracy. To determine the reproducibility of the system, three investigators measured three noncalibrated balls (20 mm, 18 mm, and 12 mm). The optical system was purposely decentered and refocused after each reading. RESULTS: Utilizing the CTS custom optics, system accuracy at the 8-millimeter test area was 0.03 (SD 0.03), 0.00, (SD 0.02), and 0.07 (SD 0.01) D respectively. Smaller diameter test areas resulted in a predicted loss of accuracy. Maximum intraobserver variability was 0.09, 0.06, and 0.11 D respectively, and maximum interobserver variability measured 0.18, 0.12, and 0.16 D. CONCLUSIONS: These data demonstrate that the PAR CTS is both highly accurate and reproducible in determining topography of spheres that approximate the curvature of the human cornea.

Algorithms↗
PubMedDate not supplied

Wear measurements in clinical studies of composite resin restorations in the posterior region: a review.

During the last twenty years, wear-evaluation methods have changed, with newer techniques developed to determine the extent of loss of material in posterior composite resin restorations functioning in the mouth. These included: direct clinical evaluation; marginal evaluation on models; heights of exposed cavity walls; volumetric assessment of impressions; profilometry and artificial or natural references; section measurements; coordinate measuring device, contact and noncontact scanning; measuring microscope; photogrammetry; moiré topography; laser interferometry; scanning electron microscopy; and optical scanning. A laser scanning technique appears to hold great potential in clinical research.

Bicuspid↗
PubMed1990

Breast form changes resulting from a certain brassière.

Eleven adult female subjects aged 22-39 years wore a certain brassière for 3 months while anthropometry and moiré fringe photographs on the anterior trunk were taken regularly once a week. After the 3 months, the brassière was not worn for another 3 months. Then the measurements and photogrammetry were repeated for comparison using superimposed moiré configurations. The results are summarized as follows. Regardless of slim or obese trunk, subjects with pendent breasts showed the highest degree of breast form "correction" from wearing the brassière. In all subjects, after 3 months of brassière constraint, the underbust circumference was smaller but the chest circumference became enlarged, the distance between the right and left nipples became wider, and the breasts tended to hang down. This change was more marked in obese subjects with pendent breasts. And when this type of subject wore a "well-fitted" brassière for a long time, her breast form became developed; that is, her breasts hung down more.

Adaptation, Physiological↗
PubMed1990

[The spread of the backspray under different working conditions].

The use of high- and highest-speed preparation instruments and the therefore required intensive spray cooling results not only in more efficient working possibilities but also in an increased infection hazard, especially for the dentist and his assistance caused by the spray rebound. Simulated preparations were carried out on different tooth surfaces at different positions of the patient with or without exhaust under clinical conditions to objectify the space spreading of the spray rebound. The arrangement of the equipment has been objectified by photogrammetry so that the measurement data could be clearly classified. The use of the spraying mist exhaust reduces the spray rebound between 50 and 65%.

Aerosols↗
PubMed1989

[Dynamic study of the optic papilla].

There are several methods of accurately measuring the contours of the papilla and rim. Of these methods, photogrammetry and its refinements are known to provide reproducible results. Unfortunately, there is a discrepancy between the accuracy of these methods and the biological "background noise". This noise does not allow the precision of these methods to be improved beyond a certain level. This also applies for determination of the color of the papilla. An alternative to this problem is to use the "provocation" test. In this article, we try to show the importance of the dynamic test of the papilla (dynamic provoked circulatory response): measuring the change in pallor of the rim during an artificial increase in the intraocular pressure.

Glaucoma↗
PubMed1989

New methods for quantitative and qualitative facial studies: an overview.

The clinical study of birth defects has traditionally followed the Gestalt approach, with a trend, in recent years, toward more objective delineation. Data collection, however, has been largely restricted to measurements from X-rays and anthropometry. In other fields, new techniques are being applied that capitalize on the use of modern computer technology. One such technique is that of remote sensing, of which photogrammetry is a branch. Cartographers, surveyors and engineers, using specially designed cameras, have applied geometrical techniques to locate points on an object precisely. These techniques, in their long-range application, have become part of our industrial technology and have assumed great importance with the development of satellite-borne surveillance systems. The close-range application of similar techniques has the potential for extremely accurate clinical measurement. We are currently evaluating the application of remote sensing to facial measurement using three conventional 35 mm still cameras. The subject is photographed in front of a carefully measured grid, and digitization is then carried out on 35-mm slides specific landmarks on the cranioface are identified, along with points on the background grid and the four corners of the slide frame, and are registered as xy coordinates by a digitizer. These coordinates are then converted into precise locations in object space. The technique is capable of producing measurements to within 1/100th of an inch. We suggest that remote sensing methods such as this may well be of great value in the study of congenital malformations.

Cephalometry↗
PubMed1989

Facial morphology as determined by anthropometry: keeping it simple.

Anthropometry remains an efficient, noninvasive method for describing craniofacial morphology in spite of the appearance of more sophisticated technologies. The major advantage afforded by anthropometry is its technical simplicity, a fact which makes it a readily available tool for evaluating patients, planning facial surgery, or delineating basic features of craniofacial syndromes. Anthropometry lacks the detail of more powerful technologies, but it is better suited for populational studies because of the availability of comparative, normal databases. The standard z-scores produced by such comparisons lend themselves to multivariate analysis. This type of comparative analysis is not yet possible for computerized tomography, three-dimensional imaging, or photogrammetry. To illustrate the utility of this technique an example is cited from an ongoing study of hypohidrotic ectodermal dysplasia (HED) in which anthropometry reveals details of facial morphology overlooked in previous studies. These include the presence of reduced facial height and a striking reduction in the size of the facial features in spite of the fact that facial widths are comparatively normal. Gene carriers show a similar though nonidentical pattern of defects. Like all morphometric approaches, anthropometry has its limitations. Well-designed protocols minimize these limitations by incorporating multiple facial dimensions in the analysis and by emphasizing careful collection of data with standard instruments and methodology.

Cephalometry↗
PubMed1988

Aqueous humor flow measured with fluorophotometry in timolol-treated primates.

Anterior chamber aqueous humor flow rate was measured in unanesthetized owl monkeys using fluorophotometry and anterior chamber photogrammetry. The mean anterior chamber turnover constant (ko) was 0.01, the mean aqueous humor flow rate was 2.75 microliters min-1, and the mean anterior chamber volume was 317 microliters in 16 eyes of eight monkeys. A significantly lower (11%, P less than 0.002) flow rate was measured in the afternoon compared to flow rates measured in the morning. This diurnal cycle is analogous to the fluctuations in flow in humans and supports the hypothesis that aqueous humor formation in primates is regulated by endogenous mechanisms. To investigate the role of adrenergic mechanisms in regulating flow, the dose-response effect of topical timolol (0.5-100 micrograms) was measured. Five microliters drops were used to minimize systemic absorption. Lower concentrations (0.01% and 0.05%) caused sporadic changes in flow. Topical 0.1% timolol (5 micrograms) significantly decreased aqueous humor flow in the treated eye compared to baseline flow while flow in the contralateral eye was not significantly different from baseline flow. Higher concentrations of timolol (0.5% and 1%) caused a dose-related bilateral decrease in flow. These results indicate that even with small topical volumes systemic absorption of the higher concentrations of timolol occurs. Significant local inhibition of flow occurred following 5 micrograms of topical timolol whereas an equal bilateral decrease in flow occurred following a 100 microgram dose. These results suggest that the standard clinical dose (approximately equal to 100 micrograms) is supramaximal for decreasing aqueous flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1995

A three-dimensional evaluation of human facial asymmetry.

Soft-tissue facial asymmetry was studied in a group of 80 young healthy white Caucasian adults (40 men, 40 women) with no craniofacial, dental or mandibular disorders. For each subject, the 3-dimensional coordinates of 16 standardised soft-tissue facial landmarks (trichion, nasion, pronasale, subnasale, B point, pogonion, eye lateral canthi, nasal alae, labial commissures, tragi, gonia) were measured by infrared photogrammetry by an automated instrument. The form of the right and left hemifaces was assessed by calculating all the possible linear distances between pairs of landmarks within side. Side differences were tested by using euclidean distance matrix analysis. The mean faces of both groups were significantly asymmetric, i.e. the 2 sides of face showed significant differences in shape, but no differences in size.

Adult↗
PubMed1994

Co-existence of oblique pinnae and congenital heart disease.

The paper reports a syndrome in which oblique placement of one or both the pinnae on face was found to co-exist with congenital anomalies of heart like VSD, PDA and Tetralogy of Fallot, etc. Although clinically discernible in 90% of the subjects, objective evidence of obliquity of pinna was documented by photogrammetry. The values for the ear inclination in subjects categorized clinically as normally placed pinna were 7.9 degrees +/- 3.39 degrees with range 2 degrees-17 degrees. In contrast, subject where the pinna was clinically categorized as oblique had mean AEI 16.5 degrees +/- 5.81 degrees with a range 5 degrees-33 degrees. Eighteen of the 20 subjects with oblique pinna were demonstrated to have some congenital anomaly of heart as indicated by clinical and echocardiographic examination. In contrast, in subjects with normally placed pinna only 3 out of 34 possessed clinical heart defects. Presence of oblique pinna indicates a thorough search for undetected heart defects.

Adolescent↗
PubMed1995

[Biomechanical study on the optimal running route for anterior cruciate ligament reconstruction].

The purpose of this study was to determine the isometric points for anterior cruciate ligament (ACL) reconstruction and to investigate notch impingement with isometric reconstruction. The length pattern of ACL was assessed by three-dimensional bi-plane X-ray photogrammetry for determining the isometric point for ACL reconstruction. The isometric points were studied in six fresh cadaveric knees with no injury in any ligament. Five femoral and four tibial attachment sites were selected for intra-articular reconstruction. In each knee, 20 different combinations were studied. For extra-articular reconstruction, three femoral and three tibial sites were selected. In these knees, nine different combinations were studied. One isometric point for intra-articular ACL reconstruction was a combination of the 5-mm superior posterior point from the femoral attachment of the ACL and the center point of the tibial attachment. The other was a combination of the anterior-proximal edge of the femoral attachment and anterior edge of the tibial attachment. There were no isometric points for extra-articular ACL reconstruction. To investigate notch impingement, eight cadaveric knees were studied. One femoral and three tibial attachment sites were selected. For the reconstructed ligaments, 8-mm and 10-mm cables were used. In each cadaveric knee, six different conditions were studied. When the tibial hole was positioned in the center of the attachment of ACL with an 8-mm graft, then notch impingement did not occur. When the tibial drill holes were positioned in a more anterior position, then notch impingement occurred in all the cadaveric knees in which an 8-mm graft was used. With the 10-mm grafts, notch impingement occurred in all three bony tunnel conditions. In these conditions, notch impingement occurred widely from the medial side of the roof to the wall of the lateral femoral condyle. Thus, if the graft diameter is greater than 8 mm, adequate notch plasty must be performed.

Anterior Cruciate Ligament↗
PubMed1978

Multiple-slit illumination of the optic disc.

A modification to a photo slit-lamp illuminator adds detail to the human optic disc surface by projecting onto it a pattern of fine parallel lines. These stripes curve as they traverse the disc, and its surface contour is revealed. Application of this technique may improve the reliability of methods used to quantitate disc topography.

Evaluation Studies as Topic↗
PubMed1978

Classification of human cataracts.

A stereoscopic system of lens photography was developed and was applied in the classification of different forms of cataract. Lenses, after surgical extraction, can be classified by a technician, independent of ophthalmological collaboration. This system meets the needs of the laboratory scientist and has been adopted by the Cooperative Cataract Research Group.

Cataract↗
PubMed1979

Optic disc parameters and onset of glaucomatous field loss. I. Methods and progressive changes in disc morphology.

Serial stereoscopic fundus photographs taken in known relationship to the onset of glaucomatous visual field loss on 12 eyes were intermixed with those from 206 age- and race-matched controls and analyzed in randomized masked fashion. Progressive changes in the size, shape, or contour of the disc, and a newly described parameter, thickness of the nerve fiber layer as it crosses the disc rim, were readily apparent by the time of onset of glaucomatous field loss in all but two abnormal eyes (one case). In the latter instance, direct comparison of stereophotos indicated progressive pallor of the remaining disc tissue. Serial stereophotographs appear superior to fundus drawings for anticipating glaucomatous field loss.

Glaucoma↗