IMAGE MAGNIFICATION IN DIGITAL FLUOROSCOPY

Image magnification is inherent in radiography. In digital fluoroscopy, the three components of magnification are geometric, electronic and photographic. In this study, the total magnification factor of a digital imaging system was determined by two methods, 1) comparison of measurements of a known object to its image and 2) calculation of geometric, electronic and photographic magnification from the imaging system specifications. Both methods were employed for various focal-film distances, image intensifier tube modes and laser printer formats. Results of these two methods were different due to the detrimental effect of penumbra on image quality with increasing magnification. If a radiographic image is to be used to approximate object size, then a technique should be used that will minimize magnification. In digital fluoroscopy this is achieved with the shortest object-film distance (assuming a fixed focal-object distance), largest image intensifler mode and greatest number of images per sheet of film.     

Cone beam computed tomography in veterinary dentistry

The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal reconstructions were created using specialized software. Image quality and visibility of anatomical landmarks were subjectively assessed by two observers. Good image quality was obtained for the MPR para-sagittal reconstructions through multiple teeth. The image quality of the panoramic reconstructions of dogs was moderate while the panoramic reconstructions of cats were poor since the images were associated with an increased noise level. Segmental panoramic reconstructions of the mouth seem to be useful for studying the dental anatomy especially in dogs. The results of this study using human dental CBCT technology demonstrate the potential of this scanning technology in veterinary medicine. Unfortunately, the moderate image quality obtained with the CBCT technique reported here seems to be inferior to the diagnostic image quality obtained from 2-dimensional dental radiographs. Further research is required to optimize scanning and reconstruction protocols for veterinary applications.     

A Direct Approach for Quantifying Stream Shading

Management and regulatory standards for stream shading have been established to mitigate excessive stream temperature. Existing shade assessment tools, however, are inadequate for monitoring extensive stream networks. Our objectives were to develop and evaluate an efficient, low-cost field technique for sampling stream-surface shading using digital images and to evaluate the efficiencies and effectiveness of eight different digital image analysis techniques for shade assessments. We developed a quadrat-based technique and associated field equipment to directly photograph stream-surface shading. Sampling at random points (pixels) within the resultant digital images was the most accurate, efficient, and robust image analysis technique. An approach pairing the photographic field technique and the random point-sampling image analysis technique should enable managers to conduct ground-based assessments of stream shading over extensive stream networks. This approach may also provide an efficient means of collecting ground truth samples for even broader scale, remote sensing–based stream-shade assessments.     

一种基于图像处理技术的高原鼠兔识别方案

高原鼠兔(Ochotona curzoniae)是破坏青藏高原草地生态的主要生物灾害之一。对高原鼠兔传统的监测与鼠情调查方法需要耗费大量的人力物力,难以实现对鼠兔长期、连续的观测研究。为此,提出了一种基于图像处理技术的高原鼠兔自动识别方案,把图像处理技术应用到鼠兔识别系统中,获取对鼠兔监测与调查的数据,为鼠兔的防治提供理论依据。与传统的监测与调查方法相比较,该方案能够实现对鼠类活动无接触、动态、连续的监测,对鼠兔的防治以及改善高原的草地生态环境具有重要意义。     

Comparison of Point Intercept and Image Analysis for Monitoring Rangeland Transects

There is global recognition that sustainable land use requires monitoring that will detect change on a scale that protects the resource. That fundamental necessity is threatened where labor-intensive methods and high labor costs cause sampling deficiencies and increased Type-II error rates (false negatives). Ground-based imaging is a monitoring method that reduces monitoring labor costs. Nadir (vertical) images acquired with common digital cameras can be manually analyzed for cover using free software. We used an innovative field protocol to acquire standardized, freehand, nadir images (samples) of rangeland, then compared point intercept (PI) and image-analysis techniques. Between methods, precision (repeatability) across users was equivalent; cover measurements were often different, and the image-analysis technique took only a third as long to complete. Image analysis has several advantages over PI besides the reduced labor cost: Images are permanent resource records available for reanalysis if data are questioned, if software improves, or if management objectives change; and image analysis is less biased by moving vegetation, moving pointing devices, and bright vegetation color.     

Use of chromametry and digital photography for objective measurement of skin color in clinically normal dogs

OBJECTIVE: To evaluate whether skin erythema in clinically normal dogs can be quantified by use of chromametry and image analysis of digital photographs. ANIMALS: 9 German Shepherd Dogs and 10 mixed-breed dogs. PROCEDURE: Hair was clipped at 7 sites on the body. Skin erythema was evaluated at the axillary region, right and left lateral aspect of thorax, right and left loin area (ie, part of the back between the thorax and pelvis), right and left groin area (ie, the junctional region between the abdomen and thigh), metatarsal digital pad, and on the nose. Replicate measurements were done by use of chromametry and image analysis of digital photographs, using erythema values in accordance with the Committee International d'Eclairage (CIE)-Lab color system. RESULTS: Repeatability was high for both techniques. Within-dog variation was lower than between-dog variation. Between-dog variation was high for both groups of dogs. Interregional variation was significant in German Shepherd Dogs and mixed-breed dogs. Erythema values revealed symmetry between the right and left lateral aspects of the thorax and loin and groin areas. CONCLUSIONS AND CLINICAL RELEVANCE: Precise objective methods are available for skin erythema quantification. Chromametric and photographic erythema values had a high within-dog reproducibility. Between-dog variability was high for German Shepherd Dogs and mixed-breed dogs as was regional variation, indicating differences in color among dogs.     

自动照相系统在野生动物调查中的应用

概述了自动照相系统的工作原理,介绍了该技术在国内外野生动物调查中的现状,同时还结合作者近几年的研究体会,分析了自动照相系统用于野生动物调查时的特点和存在问题及今后发展的趋势。作者认为,这项技术虽仍有不足,但由于自动照相系统所具有的客观性、隐蔽性、非损伤性及监测的长期性等特点,将来会在野生动物调查中具有非常重要的应用价值和可观的应用前景。     

II. Parameters to Monitor in the Trauma Patient – The Ideal.

Patient monitoring devices may be considered as extensions of the veterinary clinician's senses. Many of the parameters outlined above have been used for years, without the term “monitor” being used. In this report, several patient monitoring methods have been discussed, and their advantages weighed. It is hoped that judicious use of some of these monitoring methods may aid the veterinary clinician in diagnosis and treatment of his trauma patients.     

MONITORING THE TRAUMA PATIENT

Patient monitoring devices may be considered as extensions of the veterinary clinician's senses. Many of the parameters outlined above have been used for years, without the term “monitor” being used. In this report, several patient monitoring methods have been discussed, and their advantages weighed. It is hoped that judicious use of some of these monitoring methods may aid the veterinary clinician in diagnosis and treatment of his trauma patients.     

应用红外相机陷阱法估计荒漠啮齿动物种群密度

啮齿动物是草地生态系统中的重要成分。监测啮齿动物种群动态对于草地生态系统小型哺乳动物的生态学研究及草地鼠害控制均具有重要的意义。目前国内外对啮齿动物的种群监测主要以铗捕法、笼捕法为主,既费时又费力。红外相机技术的应用可弥补这一缺点,然而关于红外相机技术测度荒漠小型啮齿动物种群数量的研究并不多见。本研究采用红外相机陷阱法和标志重捕法对内蒙古阿拉善荒漠区主要啮齿动物的种群数量进行连续监测,并分析不同方法监测结果的优缺点,以期选择一种基于红外相机技术适合荒漠啮齿动物种群数量监测的方法。研究结果表明,基于红外相机技术的随机相遇模型和捕获率模型在评估荒漠区五趾跳鼠(Allactaga sibirica)和三趾跳鼠(Dipus sagitta)的种群密度中均具有较好效果,但是捕获率模型在评估子午沙鼠(Meriones meridianus)种群密度时效果优于随机相遇模型,且捕获率模型涉及参数较少。在监测荒漠啮齿动物种群数量时,对于跳鼠的研究两种方法均可使用,对于啮齿动物多物种种群数量研究,建议采用捕获率模型。     

The use of ultrasound in monitoring reproductive physiology of beef cattle.

Real-time, B-mode ultrasonography provides the opportunity to improve the methods of evaluation of ovarian function and diagnoses of pregnancy in beef cattle. Determination of the sex of a fetus early in pregnancy (d 55 to 85) and verification of embryo viability by monitoring fetal heartbeat are unique methods involving ultrasound scanning. These techniques and a method for evaluating the technique of artificial insemination can be used to improve reproductive management of cattle. The way in which ultrasound technology may have its greatest impact is as a tool for improving on the method of palpation per rectum for monitoring ovarian function and pregnancy in beef cows and heifers. Determination of fetal sex and monitoring embryo mortality are less likely to be applied regularly in herd management, but these procedures will be valuable in conducting research in reproductive physiology of beef cattle.     

COMPUTED TOMOGRAPHIC DETERMINATION OF TIBIAL TORSION IN THE DOG

The goal of this study was to develop a method for computed tomographic (CT) measurement of tibial torsion, and to compare this technique with direct anatomic measurement of tibial torsion in cadaveric canine tibiae. Paired hind limbs of 10 cadaveric dogs were mounted on a custom-designed limb holding apparatus. One-millimeter thick, contiguous, transverse CT slices were obtained from the distal femur to the proximal tibia and 2 mm CT slices were obtained from the distal tibia to the proximal tarsus. The tibiae were freed of soft tissues and digital photographic images of the proximal and distal articular surfaces were obtained with the camera lens aligned perpendicular to the long axis of the tibia. Multiple proximal and distal tibial axes were identified on the images; two proximal and two distal axes were found to be repeatable in all specimens in both the direct and CT methods. The torsion angle was calculated by determining the difference between the axis angles for each pair of proximal and distal axes. There was no significant difference in torsion angle identified between the direct photographic and CT method for any pair of proximal and distal axes. CT determination of tibial torsion is a rapid and accurate method, and warrants investigation in clinical patients.     

Diagnostic accuracy of digital photography and image analysis for the measurement of foot conformation in the horse

Reasons for performing study: Rigorous evaluation of practicable methods for the objective assessment of foot conformation has not been performed. Objectives: To assess the practicability, precision and accuracy of the process of obtaining measurements of horses' feet using photography and image processing software. Methods: Precision study: Lateral photographs of horses' feet were obtained twice by 2 veterinary surgeons (image acquisition ‐ IAc). Photographs were analysed by 2 masked veterinary surgeons on 2 occasions (image analysis ‐ IAn). Measurements were compared within and between operators for self and non‐self acquired photographs. Agreement indices (AIs) and 95% limits of agreement (LOA) were calculated for the IAn process alone and for the combined IAc + IAn processes. Accuracy study: Measurements obtained from lateral photographs were compared with those obtained from lateromedial radiographs. AIs and 95% LOA were calculated for each measurement. Results: Precision study: Mean intra‐ and interoperator AIs for the IAn process alone were ≥0.90 while those for the combined IAc + IAn processes were ≥0.89 for all measurements. Similar mean AIs and 95% LOA were calculated regardless of image origin. The 95% LOA for hoof angle, heel height/toe height% and coronary band angle for all comparisons were within target values. Accuracy study: Mean AIs were ≥0.89 for all measurements. The 95% LOA for heel height/toe height% and coronary band angle were within target values. Conclusions: Excellent precision was identified within and between operators regardless of image origin. High levels of accuracy were also identified, especially for heel height/toe height% and coronary band angle, indicating that photography and radiography may be used interchangeably. Potential relevance: Acquisition and analysis of photographic images is an appropriate method for the objective measurement of foot conformation, both in clinical and research settings.     

应用MODIS进行草原生物量估测误差原因分析

草原生物量遥感监测从地面调查到遥感分析涉及诸多环节和步骤,不计偶然误差,系统误差存在于每一个环节,造成系统误差的原因来自多方面,一是遥感影像的分辨率低、噪声多和处理过程中信息损失;二是地面样方信息的不确定性和片面性;三是当前遥感监测业务和技术发展水平的局限等。本研究结合当前普遍应用的草原监测方法,总结并分析了各种误差来源和对监测结果产生的影响。     

Using Very-Large-Scale Aerial Imagery for Rangeland Monitoring and Assessment: Some Statistical Considerations

The availability of very-large-scale aerial (VLSA) imagery (typically less than 1 cm ground-sampling-distance spatial resolution) and techniques for processing those data into ecosystem indicators has opened the door for routinely using VLSA imagery in rangeland monitoring and assessment. However, for VLSA imagery to provide defensible information for managers, it is crucial to understand the statistical implications of designing and implementing VLSA image studies, including consideration of image scale, sample design limitations, and the need for validation of estimates. A significant advantage of VLSA imaging is that the researcher can specify the scale (i.e., spatial resolution and extent) of the images. VLSA image programs should plan for scales that match monitoring questions, size of landscape elements to be measured, and spatial heterogeneity of the environment. Failure to plan for scale may result in images that are not optimal for answering management questions. Probability-based sampling guards against bias and ensures that inferences can be made to the desired study area. Often collected along flight transects, VLSA imagery lends itself well to certain probability-based sample designs, such as systematic sampling, not often used in field studies. With VLSA image programs, the sample unit can be an entire image or a portion of an image. It is critical to define the sampling unit and understand the relationship between measurements and estimates made from the imagery. Finally, it is important to statistically validate estimates produced from VLSA images at selected locations using quantitative data of the same scale and more precise and accurate than the VLSA image techniques. The extent to which VLSA imagery will be useful as a tool for understanding the status and trend of rangelands depends as much on the ability to build the imagery into robust programs as it does on the ability to quickly and relatively easily collect VLSA images over large landscapes.     

基于不同下垫面的农业干旱遥感监测方法与发展前景

干旱是我国农业面临的主要自然灾害之一。利用遥感手段监测农业干旱,针对作物生长发育过程中不同下垫面状况选取适用的监测指标,可以及时、有效地评估干旱对作物生长的影响,从而为各级政府部门制定防灾减灾政策提供重要的依据。本文总结了目前广泛应用的基于不同下垫面状况的农业干旱遥感监测方法,并将这些方法分为适用于裸露地表与低植被覆盖条件的监测方法、适用于中高植被覆盖条件的监测方法及适用于各种下垫面状况的综合监测方法。在此基础上,对未来农业干旱遥感监测发展方向进行了研究与探讨:1)监测数据源由单一数据源向多源数据转变;2)监测指标由单一的气象监测指标向气象、卫星遥感与作物生理物理特征相结合的综合监测指标转变;3)逐步实现"3S"技术集成与数据共享。     

A Technique for Estimating Rangeland Canopy-Gap Size Distributions From High-Resolution Digital Imagery

The amount and distribution of gaps in vegetation canopy is a useful indicator of multiple ecosystem processes and functions. In this paper, we describe a semiautomated approach for estimating canopy-gap size distributions in rangelands from high-resolution (HR) digital images using image interpretation by observers and statistical image classification techniques. We considered two different classification methods (maximum-likelihood classification and logistic regression) and both pixel-based and object-based approaches to estimate canopy-gap size distributions from 2- to 3-cm resolution UltraCamX color infrared aerial photographs for arid and semiarid shrub sites in Idaho, Nevada, and New Mexico. We compare our image-based estimates to field-based measurements for the study sites. Generally, percent of input points correctly classified and kappa coefficients of agreement for plot image classifications was very high. Plots with low kappa values yielded canopy gap estimates that were very different from field-based estimates. We found a strong relationship (R² > 0.9 for all four methods evaluated) between image- and field-based estimates of the total percent of the plot in canopy gaps greater than 50 cm for plots with a classification kappa of greater than 0.5. Performance of the remote sensing techniques varied for small canopy gaps (25 to 50 cm) but were very similar for moderate (50 to 200 cm) and large (> 200 cm) canopy gaps. Our results demonstrate that canopy-gap size distributions can be reliably estimated from HR imagery in a variety of plant community types. Additionally, we suggest that classification goodness-of-fit measures are a potentially useful tool for identifying and screening out plots where precision of estimates from imagery may be low. We conclude that classification of HR imagery based on observer-interpreted training points and image classification is a viable technique for estimating canopy gap size distributions. Our results are consistent with other research that has looked at the ability to derive monitoring indicators from HR imagery.     

巴赞影像本体论在数字电影时代的真实性解读

电影作为一种视觉艺术而存在,它的发现和完善得益于技术的发明和改进。特别是近年来,数字化电影所占的比例越来越多,技术的重要性更加凸显。然而这种新的技术也给l乜影艺术带来了不小的冲击,大量特技的运用,超出了人们的想象,电影的真实性又成为一个热点话题。而对数字电影时代艺术与真实的关系的探讨,有助于梳理巴赞“摄影影像本体论”,重新审视经典电影理论的历史地位和局限性,为我国电影事业的发展提供一个新的视角。