Influence of blur on feature matching and a geometric approach for photogrammetric deblurring

Unmanned aerial vehicles (UAV) have become an interesting and active research topic for photogrammetry. Current research is based on images acquired by a UAV, which have a high ground resolution and good spectral and radiometric resolution, due to the low flight altitudes combined with a high resolution camera. UAV image flights are also cost efficient and have become attractive for many applications including change detection in small scale areas. <br><br> One of the main problems preventing full automation of data processing of UAV imagery is the degradation effect of blur caused by camera movement during image acquisition. This can be caused by the normal flight movement of the UAV as well as strong winds, turbulence or sudden operator inputs. This blur disturbs the visual analysis and interpretation of the data, causes errors and can degrade the accuracy in automatic photogrammetric processing algorithms. <br><br> The aim of this research is to develop a blur correction method to deblur UAV images. Deblurring of images is a widely researched topic and often based on the Wiener or Richardson-Lucy deconvolution, which require precise knowledge of both the blur path and extent. Even with knowledge about the blur kernel, the correction causes errors such as ringing, and the deblurred image appears "muddy" and not completely sharp. In the study reported in this paper, overlapping images are used to support the deblurring process, which is advantageous. An algorithm based on the Fourier transformation is presented. This works well in flat areas, but the need for geometrically correct sharp images may limit the application. Deblurring images needs to focus on geometric correct deblurring to assure geometric correct measurements.

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Justifying the data analytical choice in single case research in relation to the expected data pattern

10.31234/osf.io/2b9mu ◽

2019 ◽

Author(s):

Rumen Manolov

Keyword(s):

Data Analysis ◽

Visual Analysis ◽

Multilevel Models ◽

Single Case ◽

Analytical Techniques ◽

Real Data ◽

Small Scale ◽

Data User ◽

Single Case Research ◽

User Friendly

The lack of consensus regarding the most appropriate analytical techniques for single-case experimental designs data requires justifying the choice of any specific analytical option. The current text mentions some of the arguments, provided by methodologists and statisticians, in favor of several analytical techniques. Additionally, a small-scale literature review is performed in order to explore if and how applied researchers justify the analytical choices that they make. The review suggests that certain practices are not sufficiently explained. In order to improve the reporting regarding the data analytical decisions, it is proposed to choose and justify the data analytical approach prior to gathering the data. As a possible justification for data analysis plan, we propose using as a basis the expected the data pattern (specifically, the expectation about an improving baseline trend and about the immediate or progressive nature of the intervention effect). Although there are multiple alternatives for single-case data analysis, the current text focuses on visual analysis and multilevel models and illustrates an application of these analytical options with real data. User-friendly software is also developed.

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Comparison of LPWAN Technologies: Cost Structure and Scalability

Wireless Personal Communications ◽

10.1007/s11277-021-08664-0 ◽

2021 ◽

Author(s):

Mohammad Istiak Hossain ◽

Jan I. Markendahl

Keyword(s):

Communication Technology ◽

Service Providers ◽

Communication Technologies ◽

Cost Structure ◽

Small Scale ◽

Area Network ◽

Wide Area Network ◽

Generic Framework ◽

Cost Efficient ◽

The Cost

AbstractSmall-scale commercial rollouts of Cellular-IoT (C-IoT) networks have started globally since last year. However, among the plethora of low power wide area network (LPWAN) technologies, the cost-effectiveness of C-IoT is not certain for IoT service providers, small and greenfield operators. Today, there is no known public framework for the feasibility analysis of IoT communication technologies. Hence, this paper first presents a generic framework to assess the cost structure of cellular and non-cellular LPWAN technologies. Then, we applied the framework in eight deployment scenarios to analyze the prospect of LPWAN technologies like Sigfox, LoRaWAN, NB-IoT, LTE-M, and EC-GSM. We consider the inter-technology interference impact on LoRaWAN and Sigfox scalability. Our results validate that a large rollout with a single technology is not cost-efficient. Also, our analysis suggests the rollout possibility of an IoT communication Technology may not be linear to cost-efficiency.

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Detection and thermal description of medicanes from numerical simulation

Natural Hazards and Earth System Science ◽

10.5194/nhess-14-1059-2014 ◽

2014 ◽

Vol 14 (5) ◽

pp. 1059-1070 ◽

Cited By ~ 19

Author(s):

M. A. Picornell ◽

J. Campins ◽

A. Jansà

Keyword(s):

Numerical Simulation ◽

Thermal Structure ◽

Weather Prediction ◽

Weather Forecast ◽

Small Scale ◽

Medium Range Weather Forecast ◽

Warm Core ◽

Strong Winds ◽

Nwp Model ◽

Ecmwf Model

Abstract. Tropical-like cyclones rarely affect the Mediterranean region but they can produce strong winds and heavy precipitations. These warm-core cyclones, called MEDICANES (MEDIterranean hurriCANES), are small in size, develop over the sea and are infrequent. For these reasons, the detection and forecast of medicanes are a difficult task and many efforts have been devoted to identify them. The goals of this work are to contribute to a proper description of these structures and to develop some criteria to identify medicanes from numerical weather prediction (NWP) model outputs. To do that, existing methodologies for detecting, characterizating and tracking cyclones have been adapted to small-scale intense cyclonic perturbations. First, a mesocyclone detection and tracking algorithm has been modified to select intense cyclones. Next, the parameters that define the Hart's cyclone phase diagram are tuned and calculated to examine their thermal structure. Four well-known medicane events have been described from numerical simulation outputs of the European Centre for Medium-Range Weather Forecast (ECMWF) model. The predicted cyclones and their evolution have been validated against available observational data and numerical analyses from the literature.

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Experimental Parameters Used to Study Pesticide Degradation in Soil

Weed Technology ◽

10.1017/s0890037x00045899 ◽

1996 ◽

Vol 10 (1) ◽

pp. 169-173 ◽

Cited By ~ 5

Author(s):

Michael R. Blumhorst

Keyword(s):

Small Scale ◽

Test Substance ◽

Pesticide Degradation ◽

Soil System ◽

Experimental Parameters ◽

Effective Cost ◽

Cost Efficient ◽

Efficient Mechanisms ◽

Degradation In Soil

Characterization of pesticide degradation in soil is an important component in determining the environmental impact of agriculturally-applied pesticides. Several techniques currently are being used to generate these data, but small-scale laboratory studies remain one of the most effective, cost-efficient mechanisms of evaluating pesticide behavior in soil. With small-scale studies, many different environmental factors can be incorporated into the experimental design, and with the use of14C-labeled material, these studies (often referred to as soil degradation or soil metabolism studies) provide information on test substance persistence, degradation, volatilization, and mineralization. Care must be exercised, however, in selecting the experimental parameters to be used because of the potential adverse or artificial effects on the soil system.

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Terrain-Based Shadow Correction Method for Assessing Supraglacial Features on the Greenland Ice Sheet

Frontiers in Remote Sensing ◽

10.3389/frsen.2021.690474 ◽

2021 ◽

Vol 2 ◽

Author(s):

Sasha. Z. Leidman ◽

Åsa K. Rennermalm ◽

Richard G. Lathrop ◽

Matthew. G. Cooper

Keyword(s):

Land Surface ◽

Greenland Ice Sheet ◽

Correction Method ◽

Correction Coefficient ◽

Digital Elevation ◽

Aerial Vehicle ◽

Sediment Cover ◽

Elevation Model ◽

Uav Images ◽

Gis Software

The presence of shadows in remotely sensed images can reduce the accuracy of land surface classifications. Commonly used methods for removing shadows often use multi-spectral image analysis techniques that perform poorly for dark objects, complex geometric models, or shaded relief methods that do not account for shadows cast on adjacent terrain. Here we present a new method of removing topographic shadows using readily available GIS software. The method corrects for cast shadows, reduces the amount of over-correction, and can be performed on imagery of any spectral resolution. We demonstrate this method using imagery collected with an uncrewed aerial vehicle (UAV) over a supraglacial stream catchment in southwest Greenland. The structure-from-motion digital elevation model showed highly variable topography resulting in substantial shadowing and variable reflectance values for similar surface types. The distribution of bare ice, sediment, and water within the catchment was determined using a supervised classification scheme applied to the corrected and original UAV images. The correction resulted in an insignificant change in overall classification accuracy, however, visual inspection showed that the corrected classification more closely followed the expected distribution of classes indicating that shadow correction can aid in identification of glaciological features hidden within shadowed regions. Shadow correction also caused a substantial decrease in the areal coverage of dark sediment. Sediment cover was highly dependent on the degree of shadow correction (k coefficient), yet, for a correction coefficient optimized to maximize shadow brightness without over-exposing illuminated surfaces, terrain correction resulted in a 49% decrease in the area covered by sediment and a 29% increase in the area covered by water. Shadow correction therefore reduces the overestimation of the dark surface coverage due to shadowing and is a useful tool for investigating supraglacial processes and land cover change over a wide variety of complex terrain.

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Retrieval of High-Resolution Wind Fields over the Southern Korean Peninsula Using the Doppler Weather Radar Network

Weather and Forecasting ◽

10.1175/2008waf2007084.1 ◽

2009 ◽

Vol 24 (1) ◽

pp. 87-103 ◽

Cited By ~ 23

Author(s):

S-G. Park ◽

Dong-Kyou Lee

Keyword(s):

High Resolution ◽

Korean Peninsula ◽

General Structure ◽

Three Dimensional ◽

Small Scale ◽

Wind Fields ◽

Entire Area ◽

Radar Network ◽

Strong Winds ◽

Rain Events

Abstract The performance of a radar network for retrieving high-resolution wind fields over South Korea is examined. The network consists of a total of 18 operational radars. All of the radars possess the Doppler capability and carry out plan position indicator (PPI) volume scans comprising 6–15 elevation steps at every 6 or 10 min. An examination of the coverage of the radar network reveals that the radar network allows the retrieval of three-dimensional high-resolution wind fields over the entire area of the southern Korean Peninsula as well as nearby oceans above a height of approximately 3 km. After the quality control procedures of the radar measurements, the high-resolution wind fields (a few kilometers) are extracted using multiple-Doppler wind synthesis in the Custom Editing and Display of Reduced Information in Cartesian Space (CEDRIC) package developed by NCAR. The radar-retrieved winds are evaluated using the following two rain events: 1) Typhoon Ewiniar in 2006, which resulted in strong winds and heavy rainfall over the entire southern Korean Peninsula, and 2) a well-developed hook echo with a relatively small-scale diameter of about 30 km. The wind fields retrieved from the radar network exhibit counterclockwise rotation around the typhoon center and a general structure around a hook echo such as a cyclonically rotating updraft (i.e., mesocyclone). Comparisons with the wind measurements from four UHF wind profilers for the typhoon case reveal that the u- and υ-wind components retrieved from the radar network deviate by standard deviations of 3.6 and 4.5 m s−1 over ranges from −30 to 20 m s−1 and from 0 to 40 m s−1, respectively. Therefore, it is concluded that the operational radar network has the potential to provide three-dimensional high-resolution wind fields within the mesoscale precipitation systems over almost the entire area of the southern Korean Peninsula.

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Research on Algorithm of Phase Difference Analysis Based on an Improved Windowed FFT

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.2399 ◽

2013 ◽

Vol 765-767 ◽

pp. 2399-2402

Author(s):

Bu Xin You ◽

He Zhi Liu ◽

Peng Tian ◽

Jia Xu ◽

Jing Bu

Keyword(s):

Phase Difference ◽

Phase Measurement ◽

Measurement Theory ◽

Simple Algorithm ◽

Correction Method ◽

Signal Frequency ◽

Small Scale ◽

Difference Measurement ◽

Frequency Independent ◽

System Frequency

Based on the small scale power system frequency fluctuation frequency leakage problems due to the FFT phase measurement error problem, this paper presents a high accuracy algorithm for phase difference measurement based on windowed discrete Fourier transform, the signal truncated using 4 order Blackman-Harris window, and corrects the phase correction method for discrete spectrum thus to calculate the phase difference. The algorithm for phase difference measurement theory and signal frequency independent, so there is no need to sample the signals of the whole cycle. A simple algorithm, less calculation, high precision, has strong inhibition on the harmonic and noise, simulation results verify the feasibility and effectiveness of the algorithm.

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Efficient SfM for Oblique UAV Images: From Match Pair Selection to Geometrical Verification

Remote Sensing ◽

10.3390/rs10081246 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1246 ◽

Cited By ~ 14

Author(s):

San Jiang ◽

Wanshou Jiang

Keyword(s):

Feature Matching ◽

Bundle Adjustment ◽

Imaging Systems ◽

Match Pair ◽

Software Packages ◽

Aerial Vehicle ◽

Selection For ◽

Image Pairs ◽

Uav Images ◽

Reliable Solution

Accurate orientation is required for the applications of UAV (Unmanned Aerial Vehicle) images. In this study, an integrated Structure from Motion (SfM) solution is proposed, which aims to address three issues to ensure the efficient and reliable orientation of oblique UAV images, including match pair selection for large-volume images with large overlap degree, reliable feature matching of images captured from varying directions, and efficient geometrical verification of initial matches. By using four datasets captured with different oblique imaging systems, the proposed SfM solution is comprehensively compared and analyzed. The results demonstrate that linear computational costs can be achieved in feature extraction and matching; although high decrease ratios occur in image pairs, reliable orientation results are still obtained from both the relative and absolute bundle adjustment (BA) tests when compared with other software packages. For the orientation of oblique UAV images, the proposed method can be an efficient and reliable solution.

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A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover

The Cryosphere Discussions ◽

10.5194/tcd-8-509-2014 ◽

2014 ◽

Vol 8 (1) ◽

pp. 509-536 ◽

Cited By ~ 5

Author(s):

K. Gisnås ◽

S. Westermann ◽

T. V. Schuler ◽

T. Litherland ◽

K. Isaksen ◽

...

Keyword(s):

Statistical Approach ◽

Ground Surface ◽

Grid Cell ◽

Large Degree ◽

Small Scale ◽

Statistical Representation ◽

Surface Temperatures ◽

Drifting Snow ◽

The Mean ◽

Strong Winds

Abstract. In permafrost environments exposed to strong winds, drifting snow can create a small-scale pattern of strongly variable snow heights which has profound implications for the thermal regime of the ground. Arrays of 26 to more than 100 temperature loggers were installed to record the distribution of ground surface temperatures within three study areas across a climatic gradient from continuous to sporadic permafrost in Norway. A variability of the mean annual ground surface temperature of up to 6 °C was documented within areas of 0.5 km2. The observed variation can to a large degree be explained by variation in snow height. Permafrost models employing averages of snow height for grid cells of e.g. 1 km2 are not capable of representing such sub-grid variability. We propose a statistical representation of the sub-grid variability of ground surface temperatures and demonstrate that a simple equilibrium permafrost model can reproduce the temperature distribution within a grid-cell based on the distribution of snow heights.

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A Comprehensive FISH- and Array-Based Diagnostic Screeningstrategy for the Assessment of Clinically Relevant Genetic Parameters: A Prospective Analysis of 205 Childhood ALL Cases

Blood ◽

10.1182/blood-2018-99-115761 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4082-4082

Author(s):

Oskar A. Haas ◽

Karin Nebral ◽

Sabrina Haslinger ◽

Andrea Inthal ◽

Margit König ◽

...

Keyword(s):

Copy Number ◽

Conflicts Of Interest ◽

Single Case ◽

Lymphoblastic Leukemia ◽

Diagnostic Value ◽

Screening Strategy ◽

Small Scale ◽

Gene Fusions ◽

Childhood All ◽

Cost Efficient

Abstract Background: The detailed definition of causative genomic alterations is not only an indispensable prerequisite for the predictive and prognostic subdivision of childhood acute lymphoblastic leukemia (ALL) but increasingly also one, on which individualized treatment approaches will be based on. Apart from the already well-established genetic categories, the recent identification of several new classes of potentially relevant alterations together with the increasing availability of novel therapeutic options therefore necessitates a diagnostic workflow that is able to satisfy the ensuing clinical needs in a comprehensive manner. The two most interesting changes in this context are the therapeutically targetable recurrent but rare and heterogeneous tyrosine kinase and JAK2 pathway-activating (TKA) gene fusions and the more elusive cohort of apparently relapse risk-prone cases with hitherto only vaguely defined combinations of gene region-specific copy number alterations (CNA). Despite the availability of a multitude of applicable techniques, the fast and cost-efficient identification of the entire expectable abnormality patterns still remains a challenge, especially if one needs to perform the diagnostic work-up on a single case basis. We previously proposed that these diagnostic requirements could be covered best with a systematic hierarchical FISH screening approach for the identification of gene fusions together with array (combined SNP and non-polymorphic probes) analyses of genome-wide quantitative and qualitative large- and small-scale copy number aberrations (CNAs). Material and Methods: Since June 2015 we have therefore evaluated the feasibility of such a workflow in a prospective manner and screened so far 205 patients (i.e. 184 with B- and 21 with T-ALL, including 18 relapses with 14 diagnostic/relapse pairs) that were consecutively enrolled in the Austrian AIEOP-BFM 2009 treatment study. Cytogenetic preparations served as backup, since metaphase spreads were used for further FISH clarification of otherwise unresolvable complex rearrangements or ploidy patterns if deemed necessary. All identified gene fusions were subsequently validated with single or multiplex RT-PCR analyses. Results: FISH screening was positive in 90% (184/205) of cases and provided already the most essential diagnostic clues. CNAs were present in all T-ALL and 97% (179/184) of B-ALL cases, including 13 with an IKZF1pluspattern and three with ERG deletions, which both will be used das stratifying markers in the upcoming treatment trial. Taken together, our screening strategy allowed the unambiguous classification of the vast majority of B-ALLs: 70 hyperdiploid, 3 hypodiploid, 35 ETV6-RUNX1, 6 KMT2A-rearranged, 8 TCF3-PBX1, 2 BCR-ABL1, 4 dic(9;20), 5 iAMP21, 8 IGH-rearranged, 6 P2RY8-CRLF2, 3 PAX5-rearranged, 3 ZNF384-rearranged, 2 ETV6-rearranged, 3 TKA fusion-positive and 10 so called "B-other" cases without any apparent specific abnormality. RNA-sequencing analyses of these ten cases revealed that seven of them harbored a DUX4 gene rearrangement. Conclusions: Apart from its proven practical diagnostic value, our combined FISH/array approach has also several additional advantages, especially if one considers the amount of achievable information. Both procedures require only little amount of material and are highly standardized, reproducible and robust technologies. Moreover, arrays deliver DNA-sequence-based data, the coordinates of which can be efficiently stored, processed and analyzed. As such, they not only serve as a pure diagnostic tool but also as a valuable discovery platform. Disclosures No relevant conflicts of interest to declare.

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