The influence of subpixel measurement on digital camera calibration

The aim of this work is to evaluate the influence of point measurements in images, with subpixel accuracy, and its contribution in the calibration of digital cameras. Also, the effect of subpixel measurements in 3D coordinates of check points in the object space will be evaluated. With this purpose, an algorithm that allows subpixel accuracy was implemented for semi-automatic determination of points of interest, based on Fõrstner operator. Experiments were accomplished with a block of images acquired with the multispectral camera DuncanTech MS3100-CIR. The influence of subpixel measurements in the adjustment by Least Square Method (LSM) was evaluated by the comparison of estimated standard deviation of parameters in both situations, with manual measurement (pixel accuracy) and with subpixel estimation. Additionally, the influence of subpixel measurements in the 3D reconstruction was also analyzed. Based on the obtained results, i.e., on the quantification of the standard deviation reduction in the Inner Orientation Parameters (IOP) and also in the relative error of the 3D reconstruction, it was shown that measurements with subpixel accuracy are relevant for some tasks in Photogrammetry, mainly for those in which the metric quality is of great relevance, as Camera Calibration.

Breeding value accuracy estimates for growth traits using random regression and multi-trait models in Nelore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extração de feições retas com precisão subpixel: estudo comparativo entre três métodos

In the fields of Machine Vision and Photogrammetry, extracted straight lines from digital images can be used either as vector elements of a digital representation or as control entities that allow the determination of the camera interior and exterior orientation parameters. Applications related with image orientation require feature extraction with subpixel precision, to guarantee the reliability of the estimated parameters. This paper presents three approaches for straight line extraction with subpixel precision. The first approach considers the subpixel refinement based on the weighted average of subpixel positions calculated on the direction perpendicular to the segmented straight line. In the second approach, a parabolic function is adjusted to the grey level profile of neighboring pixels in a perpendicular direction to the segmented line, followed by an interpolation of this model to estimate subpixel coordinates of the line center. In the third approach, the subpixel refinement is performed with a parabolic surface adjustment to the grey level values of neighboring pixels around the segmented line. The intersection of this surface with a normal plane to the line direction generates a parabolic equation that allows estimating the subpixel coordinates of the point in the straight line, assuming that this is the critical point of this function. Three experiments with real images were made and the approach based on parabolic surface adjustment has presented better results.

The Accuracy of National Body Fat Cutoff Levels in the Prediction of Elevated Blood Pressure among Brazilian Male Adolescents

Objective: To assess viability of the development of percentage body fat cutoffs based on blood pressure values in Brazilian adolescents.Methods: A cross-sectional study was conducted with a sample of 358 male subjects from 8 to 18 years old. Blood pressure was measured by the oscilometric method, and body composition was measured by dual-energy X-ray absorptiometry (DXA).Results: For the identification of elevated blood pressure, these nationally developed body fat cutoffs presented relative accuracy. The cutoffs were significantly associated with elevated blood pressure [odds ratio = 5.91 (95% confidence interval: 3.54-9.86)].Conclusions: Development of national body fat cutoffs is viable, because presence of high accuracy is an indication of elevated blood pressure.

Step Counting and Energy Expenditure Estimation in Patients With Chronic Obstructive Pulmonary Disease and Healthy Elderly: Accuracy of 2 Motion Sensors

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Impact on Geographic Location Accuracy due to Different Satellite Orbit Ephemerides

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Accuracy of six minute walk test, stair test and spirometry using maximal oxygen uptake as gold standard

OBJETIVO: Determinar a acurácia das variáveis: tempo de escada (tTE), potência de escada (PTE), teste de caminhada (TC6) e volume expiratório forçado (VEF1) utilizando o consumo máximo de oxigênio (VO2máx) como padrão-ouro. MÉTODOS: Os testes foram realizados em 51 pacientes. O VEF1 foi obtido através da espirometria. O TC6 foi realizado em corredor plano de 120m. O TE foi realizado em escada de 6 lances obtendo-se tTE e PTE. O VO2máx foi obtido por ergoespirometria, utilizando o protocolo de Balke. Foram calculados a correlação linear de Pearson (r) e os valores de p, entre VO2máx e variáveis. Para o cálculo da acurácia, foram obtidos os pontos de corte, através da curva característica operacional (ROC). A estatística Kappa (k) foi utilizada para cálculo da concordância. RESULTADOS: Obteve-se as acurácias: tTE - 86%, TC6 - 80%, PTE - 71%, VEF1(L) - 67%, VEF1% - 63%. Para o tTE e TC6 combinados em paralelo, obteve-se sensibilidade de 93,5% e em série, especificidade de 96,4%. CONCLUSÃO: O tTE foi a variável que apresentou a melhor acurácia. Quando combinados o tTE e TC6 podem ter especificidade e sensibilidade próxima de 100%. Estes testes deveriam ser mais usados rotineiramente, especialmente quando a ergoespirometria para a medida de VO2máx não é disponível.

Accuracy of Tc-99m-sestamibi scintimammography for breast cancer diagnosis

Scintimammography using Tc-99m-sestamibi is a noninvasive and painless diagnostic imaging method that is used to detect breast cancer when mammography is inconclusive Because of the advantages of labeling v '7,ith Tc-99m-sestamibi and its high efficiency in detecting carcinomas, it is the most widespread agent for this purpose Its accumulation in the tumor has multifactorial causes and does not depend on the presence of architectural distortion or local or diffuse density variation in the breast The objective of tfiis study was to evaluate the accuracy of scintimammography 1 for detecting breast cancer One hundred and fifty-seven patients presenting 158 palpable and non-palpable breast nodules were evaluated Three patients were male and 154 were female, aged between 14 and 81 years All patients underwent scintimammography, and the nodule was subjected i to cytological or histological study, i e, the gold standard for diagnosing cancer One hundred and eleven malignant and 47 benign nodules were detected, with predominance of ductal carcinomas (n=94) and fibroadenoma/fibrocysiic condition (n=11/n=11), respectively The mean size was 3 11 cm (7-10 cm) among the malignant nodules and 2 07 cm among the benign nodules (0 5-10 cm) The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 89, 89, 95, 78 and 89%, respectively Analysis on the histological types showed that the technique was more effective on tumors that were more aggressive, such as ductal carcinoma In this study, Tc-99m-sestamibi scintim immography was shown to be an important tool for diagnosing breast cancer when mammography was inconclusive

Accuracy of fetal gender determination in maternal plasma at 5 and 6 weeks of pregnancy

Objective To assess the viability of the early diagnosis of fetal gender in material plasma before 7 weeks of pregnancy by real-time polymerase chain reaction (real-time PCR), starting at 5 weeks of pregnancy.Method peripheral blood was collected from pregnant women, starting at 5 weeks of gestation. After centrifugation, plasma was separated for fetal DNA extraction. DNA was analyzed by quantitative real-time PCR for two genomic regions, one on the Y chromosome (DYS-14) and the other shared by both sexes (beta-globin), by the TaqMan Minor Groove Binder (MGB) probe assay. The results of the examinations were compared to fetal gender determined after delivery.Results A total of 79 examinations of fetal DNA in maternal plasma were performed for 52 pregnant women. Accuracy according to gestational age was 92.6% (25 of 27 cases) at 5 weeks, and 95.6% (22 of 23 cases) at 6 weeks. These results also demonstrate that fetal DNA is present at low concentrations in maternal plasma at 5 weeks (8.5 genome equivalents (GE)/mL) and 6 weeks (34.1 GE/mL) of pregnancy.Conclusion Quantitative real-time PCR and TaqMan MGB probes specific for the detection of fetal gender in maternal plasma starting at 5 weeks of gestation have good sensitivity and excellent specificity. Copyright (c) 2006 John Wiley & Sons, Ltd.

Accuracy of routine diagnostic tests used in paracoccidioidomycosis patients at a university hospital

The identification of appropriate laboratory measures to confirm clinical hypotheses is important in routine paracoccidioidomycosis medical care. The clinical records and laboratory reports of 401 paracoccidioidomycosis patients attended at the Tropical Diseases Area, Faculdade de Medicina de Botucatu, from 1974 to 2008 were reviewed. Direct mycological (DM), cell block (CB), histopathological (HP), and double immunodiffusion (DID) tests were evaluated before treatment. Typical Paracoccidioides brasiliensis yeast forms were observed in clinical specimens of 86% of the patients, but 14% were detected only by serological test. DM of 51 different tissue specimens produced 74.5% sensitivity, and 62.5% sensitivity was observed in 112 sputum samples. CB in 483 sputum samples generated 55.3% sensitivity. HP performed in 239 samples from different tissues revealed 96.7% sensitivity. Serology carried out in 351 patients and 200 healthy controls provided 90.0% sensitivity, 100.0% specificity, 100.0% positive predictive value, 85.1% negative predictive value and 93.6% accuracy. Comparisons of laboratory measurements performed in the same patient showed that sensitivity decreases from HP to DID to CB and DM, with the last two assays providing similar sensitivities. This study demonstrated that P. brasiliensis identification by HP, CB, and/or DM associated with DID is sufficient to establish the laboratorial diagnosis of paracoccidioidomycosis in practically all cases. (C) 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Accuracy of sagittal abdominal diameter as predictor of abdominal fat among Brazilian adults: a comparation with waist circumference

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of Impression Accuracy for Implant at Various Angulations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of different repair techniques on the accuracy of repositioning the fractured denture base

Objective:This study investigated the efficacy of different techniques for the union of fragments of a denture before repair and on the accuracy of the reposition.Materials and methods:For this study, 20 maxillary dentures made with Lucitone 550 heat-cured resin were used. Points were determined with a scanner on the cusp of the teeth, as a measurement of the segments. After digitisation, each model was exported to the AUTOCAD R 14 program and two-dimensional measurements of the distances between the marked points were made. After the initial analysis, the dentures were fractured into two segments using an impact test machine. For the repair, maxillary dentures were divided into two groups; in the first, the repair was carried out using Kerr's sticky wax and in the second group, Super Bonder was used to join the fragments, with subsequent inclusion of DENTSPLY((R)) Repair Material resin. After the repair, the points of the maxillary dentures were measured again. The numerical values obtained were tabulated to compare the measurements before fracture and after the repair. For statistical analysis, analysis of variance was employed, using a single factor and double factor, followed by the Tukey test with a reliability of 95%.Results:The results demonstrated a statistically significant difference between the materials used to join the dentures for repair, where the dentures were joined with sticky wax presented a larger variation in the distances between the points.Conclusion:The variation in distances between the points is influenced by the agent of repair.

Accuracy of Impression Techniques for Impants. Part 2-Comparison of Splinting Techniques

Purpose: The aim of this study was to compare splinting techniques for impression copings of osseointegrated implants with different angulations.Materials and Methods: Replicas (N = 24) of a metal matrix (control) containing two implants at 90 degrees and 65 degrees in relation to the horizontal surface were obtained by using four impression techniques: Technique 1 (T1), direct technique with square copings without union in open trays; Technique 2 (T2), square copings splinted with dental floss and autopolymerizing acrylic resin; Technique 3 (T3), square copings splinted with dental floss and autopolymerizing acrylic resin, sectioned and splinted again with autopolymerizing acrylic resin; Technique 4 (T4), square copings splinted with prefabricated acrylic resin bar. The impression material was polyether. The replicas were individually scanned to capture the images, which were assessed in a graphic computation program. The program allowed the angulation between the bases of the replicas and the reading screws to be measured. The images of the replicas were compared with the matrix image (control), and the differences in angulations from the control image were calculated. The analysis of variance and the Tukey test for comparisons (p < 0.05) were used for statistical analysis.Results: All groups showed significant differences in the implant angulations in comparison with the control group (p < 0.05). Group T1 showed the highest difference (1.019 degrees) followed by groups T2 (0.747 degrees), T3 (0.516 degrees), and T4 (0.325 degrees), which showed the lowest angular alteration compared to the control group. There were significant differences between inclined and straight implants in all the groups, except in group T4.Conclusions: Based on the results, the splinting of pick-up impression copings is indicated for osseointegrated implant impressions. The square copings splinted with a prefabricated acrylic resin bar presented the best results among the pick-up impression techniques evaluated in this study.