scholarly journals WEIGHTED ICP POINT CLOUDS REGISTRATION BY SEGMENTATION BASED ON EIGENFEATURES CLUSTERING

2020 ◽  
Vol XLIII-B2-2020 ◽  
pp. 217-226
Author(s):  
M. Franzini ◽  
A. M. Manzino ◽  
V. Casella
Keyword(s):  
Point Clouds ◽  
Correct Selection ◽  
City Block ◽  
Flat Terrain ◽  
Dense Point ◽  
Aerial Vehicle ◽  
Single Block ◽  
Weighted Icp ◽  
Selection Of

Abstract. Dense point clouds can be nowadays considered the main product of UAV (Unmanned Aerial Vehicle) photogrammetric processing and clouds registration is still a key aspect in case of blocks acquired apart. In the paper some overlapping datasets, acquired with a multispectral Parrot Sequoia camera above some rice fields, are analysed in a single block approach. Since the sensors is equipped with a navigation-grade sensor, the georeferencing information is affected by large errors and the so obtained dense point clouds are significantly far apart: to register them the Iterative Closes Point (ICP) technique is applied. ICP convergence is fundamentally based on the correct selection of the points to be coupled, and the paper proposes an innovative procedure in which a double density points subset is selected in relation to terrain characteristics. This approach reduces the complexity of the calculation and avoids that flat terrain parts, where most of the original points, are de-facto overweighed. Starting from the original dense cloud, eigenfeatures are extracted for each point and clustering is then performed to group them in two classes connected to terrain geometry, flat terrain or not; two metrics are adopted and compared for k-means clustering, Euclidean and City Block. Segmentation results are evaluated visually and by comparison with manually performed classification; ICP are then performed and the quality of registration is assessed too. The presented results show how the proposed procedure seem capable to register clouds even far apart with a good overall accuracy.

scholarly journals QUALITY PREDICTION OF DENSE POINTS GENERATED BY STRUCTURE FROM MOTION FOR HIGH-QUALITY AND EFFICIENT AS-IS MODEL RECONSTRUCTION

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 95-101
Author(s):  
R. Moritani ◽  
S. Kanai ◽  
H. Date ◽  
Y. Niina ◽  
R. Honma
Keyword(s):  
Structure From Motion ◽  
Point Clouds ◽  
Quality Prediction ◽  
Construction Site ◽  
Model Reconstruction ◽  
High Quality ◽  
Bridge Column ◽  
Dense Point ◽  
Selection Of

<p><strong>Abstract.</strong> In this paper, we introduce a method for predicting the quality of dense points and selecting low-quality regions on the points generated by the structure from motion (SfM) and multi-view stereo (MVS) pipeline to realize high-quality and efficient as-is model reconstruction, using only results from the former: sparse point clouds and camera poses. The method was shown to estimate the quality of the final dense points as the quality predictor on an approximated model obtained from SfM only, without requiring the time-consuming MVS process. Moreover, the predictors can be used for selection of low-quality regions on the approximated model to estimate the next-best optimum camera poses which could improve quality. Furthermore, the method was applied to the prediction of dense point quality generated from the image sets of a concrete bridge column and construction site, and the prediction was validated in a time much shorter than using MVS. Finally, we discussed the correlation between the predictors and the final dense point quality.</p>

Overview radiography of abdominal organs in dogs and cats

2020 ◽  
Vol 1 (4) ◽  
pp. 6-14
Author(s):  
V. N. Baymatov ◽  
◽  
A. V. Metelev ◽  
Keyword(s):  
Barium Sulfate ◽  
Bile Ducts ◽  
Individual Characteristics ◽  
Correct Selection ◽  
X Ray ◽  
Abdominal Organs ◽  
Modern Methods ◽  
Extrahepatic Bile Ducts ◽  
Selection Of

Today, less attention has been paid to x-ray studies of animals in connection with the advent of more modern methods. At the same time, the quality of radiopaque substances decreased, which is reflected in this article. The Omnipack, Urografin, Visipack, Barium sulfate, Iodipamide, Bilignost and Biligrafin used in radiopaque contrast studies in most cases did not reveal the hepatobiliary system. Only the last two drugs gave satisfactory results. The complexity of the X-ray examination of the biliary system in cats and dogs lies in the features of the location of the extrahepatic bile ducts and the condition of the intestine, the size of the liver, its structure, echogenicity, the state of the vessels and surrounding organs. In this work, we took into account the anatomical variants of the development and location of organs in animals, which may complicate the study or evaluation of the data obtained. These included changes in the contours, shape, location of the gallbladder and its filling. The results obtained were compared with the available general species standards, taking into account the possible individual characteristics of each animal. Other studied drugs gave satisfactory results with an overall assessment of the abdominal organs, but we preferred Omnipack. Survey radiography provides a large amount of information with the correct selection of radiopaque substances.

Measurement of High Thermodynamic Temperatures in the DLR Solar Furnace by UV-B Detection

Solar Energy ◽  
2002 ◽  
Author(s):  
Nicola Rohner ◽  
Andreas Neumann
Keyword(s):  
Temperature Measurement ◽  
Temperature Measurements ◽  
Solar Furnace ◽  
Correct Selection ◽  
Basic Material ◽  
Atmospheric Conditions ◽  
Spectral Measurements ◽  
System Temperature ◽  
Selection Of

The correct selection of the operating wavelength is essential for a precise pyrometric temperature measurement on solar irradiated samples, as the measurement may be disturbed by reflected solar radiation. Atmospheric conditions and particularly the emissivity as basic material property determine the amount of this reflected and the emitted radiation from a sample under investigation. An approach to solve this problem by using a monochromator system for temperature measurement in the UV-B range was developed and experimentally tested. With this system, temperature measurements were possible beginning at 1320°C and ranging up to about 2400°C. Two calculation methods are described and compared. The influence of the calibration temperature on the quality of the temperature measurement is shown. Measurements on a blackbody up to 1500°C were performed for calibration purpose. Temperature measurements on a real solar heated magnesia sample up to 2400°C are presented and discussed. These spectral measurements on hot bodies irradiated in the DLR Solar Furnace led to the final specification of the measurement wavelengths to be in the range from 280 nm to 293 nm.

Elements and Materials Improve the FDM Products: A Review

2016 ◽  
Vol 16 ◽  
pp. 33-51 ◽  
Author(s):  
Abduladim Salem Bala ◽  
Saidin bin Wahab ◽  
Mazatusziha binti Ahmad
Keyword(s):  
Matrix Material ◽  
Process Parameter ◽  
Correct Selection ◽  
Complex Environment ◽  
Technology Process ◽  
The Matrix ◽  
Additive Materials ◽  
Insight Into ◽  
Selection Of

This work aims to provide a review of available published literature that explores the opportunities to improve the quality of fused deposit modelling (FDM) products, particularly in medical applications. The paper presents details concerning the basis of the technology, process parameter settings and their responses, and reviews the properties of common FDM engineering/bio-materials and the available methods applied for improving their performance. Based on the researches which have been reviewed, FDM technology works within a complex environment from process parameters. Thus, it can achieve good results only with the proper settings for these parameters according to the properties of the material used. Improving the polymers is essentially based on the correct selection of additive materials, which can particularly enhance the key property/properties in the matrix material. This review provides a brief insight into FDM technology, provides an idea of the process parameter settings, the available materials and ways of modifying their properties to consequently improve the quality of FDM products.

The Gambler's Ruin Problem, Genetic Algorithms, and the Sizing of Populations

1999 ◽  
Vol 7 (3) ◽  
pp. 231-253 ◽  
Author(s):  
George Harik ◽  
Erick Cantú-Paz ◽  
David E. Goldberg ◽  
Brad L. Miller
Keyword(s):  
Genetic Algorithms ◽  
Building Blocks ◽  
Correct Selection ◽  
Problem Size ◽  
One Dimensional ◽  
Fitness Evaluation ◽  
Gambler’S Ruin ◽  
Gambler's Ruin Problem ◽  
Selection Of

This paper presents a model to predict the convergence quality of genetic algorithms based on the size of the population. The model is based on an analogy between selection in GAs and one-dimensional random walks. Using the solution to a classic random walk problem—the gambler's ruin—the model naturally incorporates previous knowledge about the initial supply of building blocks (BBs) and correct selection of the best BB over its competitors. The result is an equation that relates the size of the population with the desired quality of the solution, as well as the problem size and difficulty. The accuracy of the model is verified with experiments using additively decomposable functions of varying difficulty. The paper demonstrates how to adjust the model to account for noise present in the fitness evaluation and for different tournament sizes.

scholarly journals Visualizations of the Doblar Accumulation Basin Based on the UAV Survey

2019 ◽  
Vol 1 ◽  
pp. 1-7
Author(s):  
Klemen Kozmus Trajkovski ◽  
Gašper Štebe ◽  
Dušan Petrovič
Keyword(s):  
3D Model ◽  
Weather Conditions ◽  
Point Clouds ◽  
Water Levels ◽  
Contour Lines ◽  
Digital Elevation ◽  
Short Period ◽  
Dense Point ◽  
Aerial Vehicle ◽  
Elevation Model

<p><strong>Abstract.</strong> Our research is based on a large case study of Unmanned Aerial Vehicle (UAV) surveys, modelling and visualizations of the Doblar accumulation basin. The various approaches for UAV surveying of large, demanding terrain configurations, and the benefits of surveying products used as a basis for other interdisciplinary hydrological and environmental services were researched. The demanding mountainous terrain, the steep slopes and deep and narrow streams required detailed pre-planning of the survey, including the pre-survey terrain overview. The accumulation basin was emptied merely for a short period; thus, the survey was performed in unfavourable weather conditions, which included coldness, snowfall and wind. Point clouds were generated and georeferenced from the 4377 recorded photos. The dense point cloud contained approximately 222 million points in the medium setting and more than a billion in the high setting. A 3D model was built from the data. This became the basis for numerous further analyses and for the presentation using cartographic principles: a digital elevation model with a resolution of 10&amp;thinsp;cm, an orthophoto with a resolution of 10&amp;thinsp;cm, a 3D model draped with orthophoto, contour lines with a 1&amp;thinsp;m interval, topographic profiles, calculations of volumes at different water levels, a flythrough, augmented reality and a video simulation of the water level changes. The model can also serve as a basis for hydraulic and environmental analysis and simulations or used for analyses of the accumulation and deposition of river material compared with previous and future surveys.</p>

scholarly journals INVESTIGATIONS INTO THE QUALITY OF IMAGE-BASED POINT CLOUDS FROM UAV IMAGERY

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 539-545 ◽  
Author(s):  
H.-J. Przybilla ◽  
M. Lindstaedt ◽  
T. Kersten
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Image Data ◽  
Point Clouds ◽  
Data Sets ◽  
Test Field ◽  
Data Format ◽  
Software Packages ◽  
Dense Point

<p><strong>Abstract.</strong> The quality of image-based point clouds generated from images of UAV aerial flights is subject to various influencing factors. In addition to the performance of the sensor used (a digital camera), the image data format (e.g. TIF or JPG) is another important quality parameter. At the UAV test field at the former Zollern colliery (Dortmund, Germany), set up by Bochum University of Applied Sciences, a medium-format camera from Phase One (IXU 1000) was used to capture UAV image data in RAW format. This investigation aims at evaluating the influence of the image data format on point clouds generated by a Dense Image Matching process. Furthermore, the effects of different data filters, which are part of the evaluation programs, were considered. The processing was carried out with two software packages from Agisoft and Pix4D on the basis of both generated TIF or JPG data sets. The point clouds generated are the basis for the investigation presented in this contribution. Point cloud comparisons with reference data from terrestrial laser scanning were performed on selected test areas representing object-typical surfaces (with varying surface structures). In addition to these area-based comparisons, selected linear objects (profiles) were evaluated between the different data sets. Furthermore, height point deviations from the dense point clouds were determined using check points. Differences in the results generated through the two software packages used could be detected. The reasons for these differences are filtering settings used for the generation of dense point clouds. It can also be assumed that there are differences in the algorithms for point cloud generation which are implemented in the two software packages. The slightly compressed JPG image data used for the point cloud generation did not show any significant changes in the quality of the examined point clouds compared to the uncompressed TIF data sets.</p>

scholarly journals A SMARTPHONE-BASED 3D PIPELINE FOR THE CREATIVE INDUSTRY &ndash; THE REPLICATE EU PROJECT

2017 ◽  
Vol XLII-2/W3 ◽  
pp. 535-541 ◽  
Author(s):  
E. Nocerino ◽  
F. Lago ◽  
D. Morabito ◽  
F. Remondino ◽  
L. Porzi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Point Clouds ◽  
First Year ◽  
Automated Generation ◽  
Dense Point ◽  
Modelling Techniques ◽  
Eu Project ◽  
Selection Of ◽  
Made In

During the last two decades we have witnessed great improvements in ICT hardware and software technologies. Three-dimensional content is starting to become commonplace now in many applications. Although for many years 3D technologies have been used in the generation of assets by researchers and experts, nowadays these tools are starting to become commercially available to every citizen. This is especially the case for smartphones, that are powerful enough and sufficiently widespread to perform a huge variety of activities (e.g. paying, calling, communication, photography, navigation, localization, etc.), including just very recently the possibility of running 3D reconstruction pipelines. The REPLICATE project is tackling this particular issue, and it has an ambitious vision to enable ubiquitous 3D creativity via the development of tools for mobile 3D-assets generation on smartphones/tablets. This article presents the REPLICATE project’s concept and some of the ongoing activities, with particular attention being paid to advances made in the first year of work. Thus the article focuses on the system architecture definition, selection of optimal frames for 3D cloud reconstruction, automated generation of sparse and dense point clouds, mesh modelling techniques and post-processing actions. Experiments so far were concentrated on indoor objects and some simple heritage artefacts, however, in the long term we will be targeting a larger variety of scenarios and communities.

The method of estimation of influence the type of intersection into environmental conditions

2018 ◽  
Vol 121 ◽  
pp. 351-362
Author(s):  
Aleksander Sobota
Keyword(s):  
Quality Of Service ◽  
Transport System ◽  
Environmental Conditions ◽  
Decision Problem ◽  
Road Transport ◽  
Correct Selection ◽  
Basic Assumptions ◽  
Selection Of

Functioning of transport system is determine by the quality of service realized by infrastructure of different transport branches. In case of road transport, very important are intersections. These objects are usually a bottleneck in the network. Therefore, the correct selection of the intersection type is really important in the planning and projecting process of infrastructure. So, decision problem have to be solved by the projectors, who have an influence on these process. But the selection of the intersection type is also the multi-criteria problem. Therefore the answer on the question like, does the intersection type have an influence on environmental conditions, have been presented in the article. For this purpose, the basic assumptions of the method of selections the intersection type, and results of the measurements realized at four type of intersection located on multilane arteries, have been presented in the article.

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