scholarly journals IMAGE QUALITY IMPROVEMENTS IN LOW-COST UNDERWATER PHOTOGRAMMETRY

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 135-142 ◽  
Author(s):  
F. Neyer ◽  
E. Nocerino ◽  
A. Gruen
Keyword(s):  
Coral Reef ◽  
Image Quality ◽  
Low Cost ◽  
Chromatic Aberration ◽  
Bundle Adjustment ◽  
Quality Improvements ◽  
Free Network ◽  
Processing Steps

<p><strong>Abstract.</strong> This study presents an evaluation of a cheap consumer-grade camera used for modelling a coral reef section. We evaluate the quality of a reconstructed coral reef using GoPro cameras and a high-end camera with data from an actual coral reef dataset. We also investigate components of the processing pipeline (like image quality) separate from the final results. Because our GoPro images suffer from severe chromatic aberration, we apply different image pre-processing steps to improve their quality and show its effects on the reconstructed object points. Bundle adjustment is carried out as free networks in all cases, with a follow-up rigid 3D Helmert transformation onto a geodetic control network, carried out to define the common datum and to remove the bias from the free network results.</p>

Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 26-27
Author(s):  
K. Shibatomi ◽  
T. Yamanoto ◽  
H. Koike
Keyword(s):  
Electron Microscope ◽  
Image Quality ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Image Contrast ◽  
Objective Lens ◽  
Thick Specimen ◽  
Transmission Electron ◽  
Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

scholarly journals THE SYSTEM OVERVIEW AND GEOMETRIC IMAGE QUALITY OF THE TH-1 SATELLITE

2016 ◽  
Vol XLI-B1 ◽  
pp. 511-516
Author(s):  
Jianrong Wang ◽  
Xin Hu
Keyword(s):  
Low Cost ◽  
Bundle Adjustment ◽  
Topographic Mapping ◽  
Location Accuracy ◽  
Ground Control Points ◽  
Satellite Platform ◽  
Equivalent Frame ◽  
Camera Parameters ◽  
Th 1

The Tian-Hui 1 (TH-1) is the first stereo mapping transmission satellite in China, and the primary mission goal of the satellite is for topographic mapping at 1:50,000 scale without Ground Control Points (GCPs). 1st, 2nd and 3rd satellite of TH-1 was launched on August 24, 2010, May 6, 2012 and October 26, 2015. In TH-1 satellite, many payloads are put on a small satellite platform, which has a low cost. The optical camera of TH-1 includes Line-Matrix CCD (LMCCD) camera, high resolution camera and multispectral camera with 60 km ground swath width. To get high geometric accuracy without GCPs, the on-orbit calibration camera parameters and the Equivalent Frame Photo (EFP) Multi-functional bundle adjustment are proposed and realized in ground image processing of TH-1. In order to evaluate the location accuracy of TH-1, some testing fields are established. All GCPs of testing fields are measured by GPS. The GCPs are not participated the EFP Multi-functional bundle adjustment, and are only as Check Points (CPs) to evaluate the location accuracy. The evaluation of 1st satellite is shown: the horizontal accuracy is 10.3 m (RMSE) and the vertical accuracy is 5.7 m (RMSE) without GCPs, which can satisfy for topographic mapping at 1:50,000 scale. The overviews of TH-1 satellite are described in this paper: First, the system overview is introduced, including mission and optical camera of TH-1. Then, the on-orbit calibration camera parameters using LMCCD image and the EFP Multi-functional bundle adjustment are presented. Finally, the location performance is analysed without GCPs and with different number of GCPs. In addition, the products of TH-1 are introduced.

scholarly journals Intradialytic resistance training: an effective and easy-to-execute strategy

2019 ◽  
Vol 41 (2) ◽  
pp. 215-223
Author(s):  
Antônio Paulo André de Castro ◽  
Sergio Ribeiro Barbosa ◽  
Henrique Novais Mansur ◽  
Danielle Guedes Andrade Ezequiel ◽  
Mônica Barros Costa ◽  
...  
Keyword(s):  
Resistance Training ◽  
Adverse Events ◽  
Skeletal Muscles ◽  
Low Cost ◽  
Nephrology Care ◽  
The Mean ◽  
Muscle Groups ◽  
And Function

Abstract Chronic kidney disease (CKD) alters the morphology and function of skeletal muscles, thereby decreasing patient physical capacity (PC) and quality of life (QoL). Intradialytic resistance training (IRT) is a pragmatic tool used to attenuate these complications. However, IRT has not been strongly adopted in nephrology care centers. This study aimed to assess the efficacy and safety of a low-cost, easy-to-use IRT protocol. Methods: The study enrolled 43 patients (52.8 ± 13.85 years) on HD for five to 300 months followed from April 2014 to July 2017. The efficacy of IRT was assessed based on PC - derived from muscle strength (MS) and preferred walking speed (PWS) - and QoL. The occurrence of adverse events was used as a measure of safety. The IRT protocol consisted of exercises of moderate to high intensity for the main muscle groups performed three times a week. Results: The mean follow-up time was 9.3 ± 3.24 months, for a total of 4,374 sessions of IRT. Compliance to the protocol was 96.5 ± 2.90%, and patients presented significant improvements in MS (from 27.3 ± 11.58 Kgf to 34.8 ± 10.77 Kgf) and PWS (from 0.99 ± 0.29 m/s to 1.26 ± 0.22 m/s). Physical and emotional components of QoL also increased significantly. Conclusion: IRT led to significant increases in PC and higher scores in all domains of QoL. Important adverse events were not observed during intradialytic resistance training.

scholarly journals Learning curve evaluation upskilling retinal imaging using smartphones

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Linus G. Jansen ◽  
Payal Shah ◽  
Bettina Wabbels ◽  
Frank G. Holz ◽  
Robert P. Finger ◽  
...  
Keyword(s):  
Image Quality ◽  
Low Cost ◽  
Field Studies ◽  
Field Of View ◽  
Retinal Images ◽  
Fundus Imaging ◽  
Resource Limited ◽  
Examination Time ◽  
Significant Difference

AbstractSmartphone-based fundus imaging (SBFI) is a low-cost approach for screening of various ophthalmic diseases and particularly suited to resource limited settings. Thus, we assessed how best to upskill alternative healthcare cadres in SBFI and whether quality of obtained images is comparable to ophthalmologists. Ophthalmic assistants and ophthalmologists received a standardized training to SBFI (Heine iC2 combined with an iPhone 6) and 10 training examinations for capturing central retinal images. Examination time, total number of images, image alignment, usable field-of-view, and image quality (sharpness/focus, reflex artifacts, contrast/illumination) were analyzed. Thirty examiners (14 ophthalmic assistants and 16 ophthalmologists) and 14 volunteer test subjects were included. Mean examination time (1st and 10th training, respectively: 2.17 ± 1.54 and 0.56 ± 0.51 min, p < .0001), usable field-of-view (92 ± 16% and 98 ± 6.0%, p = .003) and image quality in terms of sharpness/focus (p = .002) improved by the training. Examination time was significantly shorter for ophthalmologists compared to ophthalmic assistants (10th training: 0.35 ± 0.21 and 0.79 ± 0.65 min, p = .011), but there was no significant difference in usable field-of-view and image quality. This study demonstrates the high learnability of SBFI with a relatively short training and mostly comparable results across healthcare cadres. The results will aid implementing and planning further SBFI field studies.

scholarly journals TECHNICAL CONSIDERATIONS IN LOW-COST HERITAGE DOCUMENTATION

2019 ◽  
Vol XLII-2/W17 ◽  
pp. 225-232
Author(s):  
A. Murtiyoso ◽  
P. Grussenmeyer ◽  
D. Suwardhi
Keyword(s):  
Point Cloud ◽  
Low Cost ◽  
Bundle Adjustment ◽  
Ease Of Use ◽  
Cloud Data ◽  
Heritage Sites ◽  
Common Reference ◽  
Trade Offs ◽  
Dense Point

Abstract. The use of photogrammetry in 3D heritage documentation has matured over the recent years. In the same time, many types of sensors have also been developed in the field of imaging. While photogrammetry is considered as a low-cost alternative to TLS, several options exist in terms of sensor type with trade-offs between price, ease of use, and quality of resolution. Nevertheless, a proper knowledge on the acquisition and processing is still required to generate acceptable results. This paper aims to compare three photogrammetric sensors, namely a classical DSLR camera, a drone, and a spherical 360° camera in documenting heritage sites. Main comparison points include quality of the bundle adjustment and quality of the dense point cloud. However, an important point of the paper is also to determine whether a sensor at a given cost and effort is enough for documentation purposes. A TLS point cloud data was used as a common reference, as well as control and check points issued from geodetic surveying. In the aftermath of the comparison, several technical suggestions and recommendations were proposed as regards to the use of each sensor.

scholarly journals THE SYSTEM OVERVIEW AND GEOMETRIC IMAGE QUALITY OF THE TH-1 SATELLITE

2016 ◽  
Vol XLI-B1 ◽  
pp. 511-516
Author(s):  
Jianrong Wang ◽  
Xin Hu
Keyword(s):  
Low Cost ◽  
Bundle Adjustment ◽  
Topographic Mapping ◽  
Location Accuracy ◽  
Ground Control Points ◽  
Satellite Platform ◽  
Equivalent Frame ◽  
Camera Parameters ◽  
Th 1

The Tian-Hui 1 (TH-1) is the first stereo mapping transmission satellite in China, and the primary mission goal of the satellite is for topographic mapping at 1:50,000 scale without Ground Control Points (GCPs). 1st, 2nd and 3rd satellite of TH-1 was launched on August 24, 2010, May 6, 2012 and October 26, 2015. In TH-1 satellite, many payloads are put on a small satellite platform, which has a low cost. The optical camera of TH-1 includes Line-Matrix CCD (LMCCD) camera, high resolution camera and multispectral camera with 60 km ground swath width. To get high geometric accuracy without GCPs, the on-orbit calibration camera parameters and the Equivalent Frame Photo (EFP) Multi-functional bundle adjustment are proposed and realized in ground image processing of TH-1. In order to evaluate the location accuracy of TH-1, some testing fields are established. All GCPs of testing fields are measured by GPS. The GCPs are not participated the EFP Multi-functional bundle adjustment, and are only as Check Points (CPs) to evaluate the location accuracy. The evaluation of 1st satellite is shown: the horizontal accuracy is 10.3 m (RMSE) and the vertical accuracy is 5.7 m (RMSE) without GCPs, which can satisfy for topographic mapping at 1:50,000 scale. The overviews of TH-1 satellite are described in this paper: First, the system overview is introduced, including mission and optical camera of TH-1. Then, the on-orbit calibration camera parameters using LMCCD image and the EFP Multi-functional bundle adjustment are presented. Finally, the location performance is analysed without GCPs and with different number of GCPs. In addition, the products of TH-1 are introduced.

scholarly journals High-Frequency Acoustic Imaging Using Adhesive-Free Polymer Transducer

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1462
Author(s):  
Abhishek Ranjan ◽  
Chengxiang Peng ◽  
Sanat Wagle ◽  
Frank Melandsø ◽  
Anowarul Habib
Keyword(s):  
Image Quality ◽  
Low Cost ◽  
Human Articular Cartilage ◽  
Cartilage Sample ◽  
Environment Friendly ◽  
Depth Imaging ◽  
Piezoelectric Polymer ◽  
B Scan Images ◽  
Scanning Acoustic Microscope

The piezoelectric polymer PVDF and its copolymers have a long history as transducer materials for medical and biological applications. An efficient use of these polymers can potentially both lower the production cost and offer an environment-friendly alternative for medical transducers which today is dominated by piezoelectric ceramics containing lead. The main goal of the current work has been to compare the image quality of a low-cost in-house transducers made from the copolymer P(VDF-TrFE) to a commercial PVDF transducer. Several test objects were explored with the transducers used in a scanning acoustic microscope, including a human articular cartilage sample, a coin surface, and an etched metal film with fine line structures. To evaluate the image quality, C- and B-scan images were obtained from the recorded time series, and compared in terms of resolution, SNR, point-spread function, and depth imaging capability. The investigation is believed to provide useful information about both the strengths and limitations of low-cost polymer transducers.

Coal cinder filtration as pretreatment with biological processes to treat pharmaceutical wastewater

2010 ◽  
Vol 62 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Wei Zheng ◽  
Xiao-ming Li ◽  
Zhi-ming Hao ◽  
Dong-bo Wang ◽  
Qi Yang ◽  
...  
Keyword(s):  
Low Cost ◽  
Pharmaceutical Wastewater ◽  
Effluent Quality ◽  
Strong Adsorption ◽  
Wastewater Quality ◽  
Removal Efficiencies ◽  
Effluent Waste ◽  
Biological Treatment Process

This study aims at coupling coal cinder filter with biological process to improve pharmaceutical wastewater quality and reduce the disposal cost. In the coal cinder filter, the removal efficiencies of COD, BOD5, SS and color were 90 ± 2%, 72 ± 2%, 95 ± 2% and 80 ± 2%, respectively. The results attribute to the big specific surface area and strong adsorption ability. Coal cinder filter removes a large portion of the pollutants in the influent wastewater, which would strongly stable the effluent waste water quality, and reduce the load of follow-up biological treatment process. The average removal efficiencies for COD, BOD5, SS and color of the combined process were about 99.7 ± 3%, 98.2 ± 4%, 98.5 ± 3% and 96.3 ± 2%, respectively, with the average effluent quality of COD 16 ± 1 mg/L, BOD5 11 ± 1 mg/L, SS 10 ± 0.6 mg/L and color 22 ± 1 (multiple), which are consistent with the national requirements of the waste pollutants for pharmaceutical industry of chinese traditional medicine discharge standard (GB 21906-2008). The results indicated that the combined procedure could offer an attractive solution for pharmaceutical wastewater treatment with considerable low cost.

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