Laser-based detection and depth estimation of dry and water-filled potholes: A geometric approach

In secondary Indian roads, one often encounters potholes which can be either dry or water-filled. Accordingly, to ensure safe driving, it is imperative to detect potholes and estimate their depths in either condition. In this paper, we develop a physics-based geometric framework, where such detection and depth-estimation can be accomplished using suitable laser. Specifically, we relate dry pothole depth to measured optical deviation using simple ray optics. Further, we use Snell's law of refraction to obtain a quartic equation, and its appropriate real root to relate water-filled pothole depth to the corresponding optical deviation. Here we take into account diminishing resolu- tion with increasing distance from the camera. We conclude by experimentally validating our method

Quantitative shadow compensated optical coherence tomography of choroidal vasculature

Conventionally rendered optical coherence tomography (OCT) images of the posterior segment contain shadows which influence the visualization of deep structures such as the choroid. The purpose of this study was to determine whether OCT shadow compensation (SC) alters the appearance of the choroid and the apparent choroidal vascularity index (CVI), an OCT-derived estimated ratio of luminal to total choroidal volume. All scans were shadow compensated using a previously published algorithm, binarized using a novel validated algorithm and extracted binarized choroid to estimate CVI. On 27 raw swept-source OCT volume-scans of healthy subjects, the effect of SC on CVI was established both qualitatively and quantitatively. In shadow compensated scans, the choroid was visualized with greater brightness than the neurosensory retina and the masking of deep tissues by retinal blood vessels was greatly reduced. Among study subjects, significant mean difference in CVI of -0.13 was observed between raw and shadow compensated scans. Conventionally acquired OCT underestimates both choroidal reflectivity and calculated CVI. Quantitative analysis based on subjective grading demonstrated that SC increased the contrast between stromal and luminal regions and are in agreement with true tissue regions. This study is warranted to determine the effects of SC on CVI in diseased eyes

Amplitude-scan classification using artificial neural networks

Optical coherence tomography (OCT) images semi-transparent tissues noninvasively. Relying on backscatter and interferometry to calculate spatial relationships, OCT shares similarities with other pulse-echo modalities. There is considerable interest in using machine learning techniques for automated image classifcation, particularly among ophthalmologists who rely heavily on diagnostic OCT.Artifcial neural networks (ANN) consist of interconnected nodes and can be employed as classifers after training on large datasets. Conventionally, OCT scans are rendered as 2D or 3D humanreadable images of which the smallest depth-resolved unit is the amplitude-scan refectivity-function profle which is difcult for humans to interpret. We set out to determine whether amplitude-scan refectivity-function profles representing disease signatures could be distinguished and classifed by a feed-forward ANN. Our classifer achieved high accuracies after training on only 24 eyes, with evidence of good generalization on unseen data. The repertoire of our classifer can now be expanded to include rare and unseen diseases and can be extended to other disciplines and industries

Choroidal vascularity map in unilateral central serous chorioretinopathy: A comparison with fellow and healthy eyes

Background: To map the choroidal vascularity index and compare two eyes in patients with unilateral central serous chorioretinopathy (CSCR). Methods: This was a retrospective, observa-tional study performed in patients with unilateral CSCR. Choroidal thickness (CT) and Choroidal vascularity index (CVI) were measured and mapped in various zones according to the early treatment diabetic retinopathy (ETDRS) grid. Results: A total of 20 CSCR patients (20 study and 20 fellow eyes) were included in the study. Outer nasal region CT was seen to be significantly lower than central CT (p = 0.042) and inner nasal CT (p = 0.007); outer ring CT was significantly less than central (p = 0.04) and inner ring (p = 0.01) CT in CSCR eyes. On potting all the CVI values against the corresponding CT values, a positive correlation was seen in CSCR eyes (r = 0.54, p < 0.01), which was slightly weaker in fellow eyes (r = 0.3, p < 0.01) and a negative correlation was seen in healthy eyes (r = −0.262, p < 0.01). Conclusions: Correlation between CVI and CT was altered in CSCR eyes as compared to fellow and normal eyes with increasing CVI towards the center of the macula and superiorly in CSCR eyes

Structural Features of Patients with Drusen-like Deposits and Systemic Lupus Erythematosus

Background: The relevance of drusen-like deposits (DLD) in patients with systemic lupus erythematosus (SLE) is to a large extent uncertain. Their genesis is proposed to be correlated to immune-complex and complement depositions in the framework of SLE. The intention of this study was to determine potential morphological differences in the choroid and retina as well as potential microvascular changes comparing two cohorts of SLE patients divergent in the presence or absence of DLD using multimodal imaging. Methods: Both eyes of 16 SLE patients with DLD were compared to an age- and sex-matched control-group consisting of 16 SLE patients without detectable DLD. Both cohorts were treated with hydroxychloroquine (HCQ) and did not differ in the treatment duration or dosage. Using spectral-domain optical coherence tomography (SD-OCT) choroidal volume measures, choroidal vascularity indices (CVI) and retinal layer segmentation was performed and compared. In addition, by the exploitation of optical coherence tomography angiography vascular density, perfusion density of superficial and deep retinal capillary plexuses and the choriocapillaris were analyzed. For the choroidal OCT-scans, a subset of 51 healthy individuals served as a reference-group. Results: CVI measures revealed a significant reduction in eyes with DLD compared to healthy controls (0.56 (0.54–0.59) versus 0.58 (0.57–0.59) (p = 0.018) and 0.56 (0.54–0.58) versus 0.58 (0.57–0.60) (p < 0.001)). The photoreceptor cell layer presented significant thinning in both eyes of subjects with DLD compared to control subjects without DLD (68.8 ± 7.7 µm vs. 77.1 ± 7.3 µm for right eyes, p = 0.008, and 66.5 ± 10.5 µm vs. 76.1 ± 6.3 µm for left eyes, p = 0.011). OCTA scans revealed no significant changes, yet there could be observed numerically lower values in the capillary plexuses of the retina in eyes with DLD than in eyes without DLD. Conclusions: Our results illustrated significant alterations in the choroidal and retinal analyzes, suggesting a correlation between DLD and the progression of inflammatory processes in the course of SLE leading to retinal degeneration. For this reason, DLD could serve as a biomarker for a more active state of disease

Euclidean Auto Calibration of Camera Networks: Baseline Constraint Removes Scale Ambiguity

Metric auto calibration of a camera network from multiple views has been reported by several authors. Resulting 3D reconstruction recovers shape faithfully, but not scale. However, preservation of scale becomes critical in applications, such as multi-party telepresence, where multiple 3D scenes need to be fused into a single coordinate system. In this context, we propose a camera network configuration that includes a stereo pair with known baseline separation, and analytically demonstrate Euclidean auto calibration of such network under mild conditions. Further, we experimentally validate our theory using a four-camera network. Significantly, our method not only recovers scale, but also compares favorably with the well known Zhang and Pollefeys methods in terms of shape recovery

Smart camera networks: An analytical framework for auto calibration without ambiguity

With the proliferation of smart environment, smart multi-camera networks assume growing significance. Specifically, non-intrusive calibration of such camera networks becomes imperative in smart applications such as telepresence systems, where multi-view imaging/recording needs to be performed in a dynamic setting with continuously changing intrinsic and extrinsic camera parameters. Unfortunately, popular auto calibration methods are known to introduce ambiguity or require manual intervention. In this backdrop, we propose a three-camera configuration (which can be generalized) with a stereo pair having known baseline distance and an additional (mono) camera positioned arbitrarily, and analytically establish the uniqueness of auto calibration in the proposed configuration

Data mining methodologies and application for libraries. Library marketing for improving patron satisfaction : Expectation to the improvement of library services by data analysis

図書館学の五法則にも謳われているように図書館は時代に合った利用者サービスを求めて変わり続けなければならない。現在進行している高度情報化社会への流れは，携帯電話などによるネットワーク情報端末の進化によってもたらされたものである。このような社会変化やそれに伴う利用者の変化に図書館が対応し続けていくためには，マーケティングの手法を取り入れ，利用者の要望に従来以上に応えられる態勢を構築する必要がある。本稿では，図書館マーケティングに関して，概念の定義や手法開発へのアイディアなどを示し，その重要性を訴える。今後有益な手法を具体的に開発し，将来の図書館にとって核となるサービスモデルを構築しなければならない。As was described in the Five Laws of Library Science, libraries are supposed to keep changing and providing their patrons with up-to-date information services. We are in a rapidly changing society now due to the development of mobile network terminals like smart phones. In order to adapt to such a rapid change, libraries should adopt the concept and technologies of marketing. It is the only way for them to survive so that they can keep getting to be accepted as reliable and necessary organization by their patrons. In this paper we define, present potentiality of library markething, and demonstrate its importance. We have to keep investigating the beneficial methods and to construct the service model for the futute libraries

A Fundamental Study on Huai Nan Tzu-Ti Hsing Hs?n (『淮南子』地形訓)

We present the results of the first-ever subjective evaluation of true 3D images performed on a light field display. Given the ever-increasing volume of true 3D image content being created and consumed, it is imperative to construct a systematic framework for the subjective evaluation of such content. We first describe our experimental setup and propose a methodology for subjective evaluation on the setup. We then describe the dataset used for our study. Subjective evaluation results are reported for 20 subjects. In addition to subjective results, we also report results of popular full-reference objective 2D image quality assessment methods applied on a per view basis