scholarly journals VALIDATION OF LIDAR CALIBRATION USING A LIDAR SIMULATOR

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 39-44
Author(s):  
G. Lee ◽  
J. Cheon ◽  
I. Lee
Keyword(s):  
Lidar Measurement ◽  
Intrinsic Parameter ◽  
Geometric Information ◽  
Simulation Data ◽  
Scanning Method ◽  
Intrinsic Parameters ◽  
Estimated Parameters ◽  
Surrounding Environment ◽  
Extrinsic Parameters ◽  
Lidar Calibration

Abstract. LIDAR is being widely used for mapping and modelling because it accurately scans and acquires 3D geometric information of the surrounding environment. In order to improve the accuracy of the LIDAR measurement, it is necessary to precisely estimate the intrinsic parameters as well as extrinsic parameters and eliminate the systematic errors. Many studies are conducted to eliminate these errors caused by the intrinsic parameters of LIDAR. However, when the result of intrinsic calibration is verified using actual LIDAR data, there is a problem that other error factors cannot be excluded. Therefore, in this study, the LIDAR intrinsic calibration is verified by using a LIDAR simulator that simulates the mechanism of the actual LIDAR. When constructing a LIDAR simulator, the systematic error is inserted according to the intrinsic parameter model of LIDAR. And according to the method of scanning with LIDAR, it is divided into upright scanning and tilted scanning, and the error included LIDAR simulation data is generated. After that, the intrinsic parameters are estimated by applying the plane-based intrinsic calibration. Since values of the intrinsic parameters are known, they are compared with the estimated parameters, and the results of estimate are analyzed according to the scanning method.

Determining Intrinsic Parameters and Pose of Cameras from Single View with Variable Focal Length

2014 ◽  
Vol 635-637 ◽  
pp. 1011-1017
Author(s):  
Gui Hua Liu ◽  
Hui Min Long
Keyword(s):  
Focal Length ◽  
Pinhole Camera ◽  
Projection Matrix ◽  
Camera Model ◽  
Intrinsic Parameter ◽  
Simulation Data ◽  
Single View ◽  
Estimated Parameters ◽  
Orientation Matrix ◽  
Camera Location

This study claims an algorithm of calibration which is executed on the basis of projection matrix. This algorithm directly estimates intrinsic parameter on the basis of rotation matrix’s unitary orthogonality combined with Cholesky decomposition from the obtained projection matrix. Then, false is excluded by rotation matrix’s determinant constraints, and ultimately, camera location and orientation matrix are obtained and estimated parameters are optimized with the minimum error of reprojection residual being cost function. This algorithm is taken under a pinhole camera model and can calibrate the camera from single view with variable focal length. Both simulation data and true image experiments have proved the feasibility and robustness of this algorithm.

scholarly journals An Intrinsic Parameter Calibration Method for R-LAT System Based on CMM

2021 ◽  
Author(s):  
Wenjun Su ◽  
Junkang Guo ◽  
Zhigang Liu ◽  
Kang Jia
Keyword(s):  
Large Scale ◽  
Mathematic Model ◽  
Calibration Method ◽  
Initial Guess ◽  
Least Square ◽  
Target Point ◽  
Parameter Calibration ◽  
Intrinsic Parameter ◽  
Intrinsic Parameters ◽  
Equation Group

Abstract Rotary-laser automatic theodolite (R-LAT) system is a distributed large-scale metrology system, which provides parallel measurement in scalable measurement room without obvious precision losing. Each of R-LAT emits two nonparallel laser planes to scan the measurement space via evenly rotation, while the photoelectric sensors receive these laser planes signals and performs the coordinate calculation based on triangulation. The accurate geometric parameters of the two laser planes plays a crucial role in maintaining the measurement precision of R-LAT system. Practically, the geometry of the two laser plane, which is termed as intrinsic parameters, is unknown after assembled. Therefore, how to figure out the accurate intrinsic parameters of each R-LAT is a fundamental question for the application of R-LAT system. This paper proposed an easily operated intrinsic parameter calibration method for R-LAT system with adopting coordinate measurement machine. The mathematic model of laser planes and the observing equation group of R-LAT are established. Then, the intrinsic calibration is formulated as a nonlinear least square problem that minimize the sum of deviations of target points and laser planes, and the ascertain of its initial guess is introduced. At last, experience is performed to verify the effectiveness of this method, and simulations are carried out to investigate the influence of the target point configuration on the accuracy of intrinsic parameters.

scholarly journals Study of Thermal Comfort in Traditional House Buildings (Case Study: Simalungun Traditional House)

2021 ◽  
Vol 5 (1) ◽  
pp. 90-99
Author(s):  
Vinky Rahman ◽  
Luqman Hadi Wibowo
Keyword(s):  
Thermal Comfort ◽  
Measurement Data ◽  
Thermal Conditions ◽  
Research Problem ◽  
Simulation Data ◽  
Positive Potential ◽  
Traditional Architecture ◽  
Long Period ◽  
Surrounding Environment

Abstract. Traditional houses were formed over a long period and are believed to be hereditary responsive to the surrounding physical and socio-cultural environment. Traditional Architecture is a building whose shape, decoration and method of implementation are passed down from generation to generation. Traditional architecture is a reflection of the values and culture that the community has interpreted. The adaptation of residents in the house is carried out by optimizing the positive potential of the surrounding environment and minimizing disturbances related to the comfort of living. The research problem is how the level of thermal comfort in the traditional house of Simalungun. The purpose of this study is to analyze the thermal comfort of the study object of the Simalungun traditional house. To determine the thermal conditions inside and outside the building, Measurements of temperature and humidity were carried out. Measurement data were analyzed and compared with Ecotech simulation data. The results of research carried out directly and simulating using Ecotech. This Simalungun traditional house can be categorized as having optimal comfort in terms of its physical physiological aspects and simulate using Ecotech simulations. As for the benefits of the research, it is hoped that it can provide knowledge about the thermal comfort of traditional houses, especially the traditional houses of Simalungun.

scholarly journals A Real-Time Deformation Monitoring Method for Large-Scale Structure Based on Relay Camera

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Chuan He ◽  
Lianxiong Liu ◽  
Changhua Hu
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Large Scale Structure ◽  
Deformation Monitoring ◽  
Scale Structure ◽  
Monitoring Method ◽  
The Real ◽  
Intrinsic Parameters ◽  
Time Deformation ◽  
Extrinsic Parameters

In the process of the deformation monitoring for large-scale structure, the mobile vision method is often used. However, most of the existent researches rarely consider the real-time property and the variation of the intrinsic parameters. This paper proposes a real-time deformation monitoring method for the large-scale structure based on a relay camera. First, we achieve the real-time pose-position relationship by using the relay camera and the coded mark points whose coordinates are known. The real-time extrinsic parameters of the measuring camera are then solved according to the constraint relationship between the relay camera and the measuring camera. Second, the real-time intrinsic parameters of the measuring camera are calculated based on the real-time constraint relationship among the extrinsic parameters, the intrinsic parameters, and the fundamental matrix. Finally, the coordinates of the noncoded measured mark points, which are affixed to the surface of the structure, are achieved. Experimental results show that the accuracy of the proposed method is higher than 1.8 mm. Besides, the proposed method also possesses the real-time and automation property.

Improved Camera Calibration Method Based on Vanishing Points

2012 ◽  
Vol 182-183 ◽  
pp. 649-654
Author(s):  
Yong Yong Duan ◽  
Xiu Mei Zhang ◽  
Long Zhao
Keyword(s):  
Camera Calibration ◽  
Calibration Method ◽  
Intrinsic Parameter ◽  
Vanishing Points ◽  
Surveillance Camera ◽  
Extrinsic Parameters

To improve the accuracy and efficiency of field camera calibration, an improved fast camera calibration method is proposed. Nonlinear translation algorithm based on calibration field is adopted to solve intrinsic parameter while an improved vanishing points method is introduced to get extrinsic parameters. Surveillance camera is used to validate the proposed approach. Experiment results show that the algorithm is convenient and feasible.

scholarly journals CFNet: LiDAR-Camera Registration Using Calibration Flow Network

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8112
Author(s):  
Xudong Lv ◽  
Shuo Wang ◽  
Dong Ye
Keyword(s):  
Autonomous Vehicles ◽  
Degrees Of Freedom ◽  
Image Data ◽  
Ground Truth ◽  
Geometric Information ◽  
Six Degrees Of Freedom ◽  
Calibration Methods ◽  
Extrinsic Parameters ◽  
Calibration Algorithm ◽  
Complex Optimization

As an essential procedure of data fusion, LiDAR-camera calibration is critical for autonomous vehicles and robot navigation. Most calibration methods require laborious manual work, complicated environmental settings, and specific calibration targets. The targetless methods are based on some complex optimization workflow, which is time-consuming and requires prior information. Convolutional neural networks (CNNs) can regress the six degrees of freedom (6-DOF) extrinsic parameters from raw LiDAR and image data. However, these CNN-based methods just learn the representations of the projected LiDAR and image and ignore the correspondences at different locations. The performances of these CNN-based methods are unsatisfactory and worse than those of non-CNN methods. In this paper, we propose a novel CNN-based LiDAR-camera extrinsic calibration algorithm named CFNet. We first decided that a correlation layer should be used to provide matching capabilities explicitly. Then, we innovatively defined calibration flow to illustrate the deviation of the initial projection from the ground truth. Instead of directly predicting the extrinsic parameters, we utilize CFNet to predict the calibration flow. The efficient Perspective-n-Point (EPnP) algorithm within the RANdom SAmple Consensus (RANSAC) scheme is applied to estimate the extrinsic parameters with 2D–3D correspondences constructed by the calibration flow. Due to its consideration of the geometric information, our proposed method performed better than the state-of-the-art CNN-based methods on the KITTI datasets. Furthermore, we also tested the flexibility of our approach on the KITTI360 datasets.

scholarly journals INTRINSIC PARAMETERS OF DRY CHOPPED MISCANTHUS FOR COLD PARTICLE DYNAMIC MODELING

2020 ◽  
Vol 82 (5) ◽  
Author(s):  
Pasymi ◽  
Yogi Wibisono Budhi ◽  
Yazid Bindar
Keyword(s):  
Dynamic Modeling ◽  
Average Energy ◽  
Particle Dynamics ◽  
Particle Dynamic ◽  
Cylinder Wall ◽  
Intrinsic Parameter ◽  
Furnace Design ◽  
Intrinsic Parameters ◽  
Parameter Values ◽  
Tangential Inlet

Miscanthus is a bioenergy crop that is very easy to cultivate. It has high volatile content with an average energy value of about 18.8 MJ/kg on a dry basis. With the benefits mentioned above, Miscanthus is potential as a fuel for the suspended furnace. Therefore, the furnace design for the Miscanthus particle needs to be developed immediately. A relatively fast and low-cost technique to develop a burner furnace design is the modeling. This study aims to determine the intrinsic parameter values of dry Miscanthus particles needed in cold particle dynamic modeling. The various reasonable experimental techniques were used to obtain these parameter’s values. Then, a series of simulations and experiments of dry chopped Miscanthus dynamic in a special burner was conducted to assess the conformity of these values. The intrinsic parameters values of dry chopped Miscanthus obtained are as follows; shape factor (fs) 0.52, true particle density (ρp) 245 kg m-3, minimum, maximum, and mean particle diameters (dp) 106, 9520, and 1384 µm respectively, and spread parameter (n) 1.22. Qualitatively, the particle dynamic simulation results, using RSM and k-e models, showed similar particle pathlines to the experiment results, in terms of the frequency and intersection of the helical structure formed in the burner cylinder. It indicates that the intrinsic parameter values obtained in this study are reliable results and can be used for further simulation works. In addition, particle dynamics experiments and simulations also revealed that the particle pathline in the burner cylinder tend to move near the cylinder wall in a helical pattern; a single helix pattern in a single tangential inlet burner and a double helix pattern in a double tangential inlets burner. Regardless of the effect of the tangential inlet number, the helical pattern in the burner cylinder was also influenced by the initial swirl number (ISN) of the flow. The lower the ISN, the lower the helical frequency formed and vice versa. This study also proved that at low to moderate swirl intensities, the k-e turbulent model can be relied upon to model particle dynamics in a cyclone burner.

A Twice Calibrating Method for Binocular Stereovision System

2013 ◽  
Vol 333-335 ◽  
pp. 161-166
Author(s):  
Yang Chuan Liu ◽  
Xin Gao ◽  
Wei Wei Fu ◽  
Chuan Xu ◽  
Yun Teng
Keyword(s):  
Target Tracking ◽  
Intrinsic Parameters ◽  
Extrinsic Parameters ◽  
Calibration Pattern ◽  
Close Range ◽  
Novel Method ◽  
Calibration Accuracy ◽  
The Cross ◽  
Binocular Stereovision

Binocular stereovision system is regularly only calibrated once, that is each camera is calibrated using a picture of the calibration pattern laid in the cross field. This methods calibration accuracy is expected to be improved. A twice calibrating method is proposed here. Each cameras extrinsic and intrinsic parameters are calibrated in different fields. The extrinsic parameters are firstly calibrated in the cross field, then the intrinsic parameters are calibrated in the close-range field. By applying the method to one binocular stereovision system built in our lab, it is demonstrated that the proposed method can improve the calibration accuracy more than 3.4dB than the once calibrating method. Its accuracy makes this novel method more suitable for high accurate target tracking application.

scholarly journals Cumulative material damage from train of ultrafast infrared laser pulses

2019 ◽  
Vol 7 ◽  
Author(s):  
A. Hanuka ◽  
K. P. Wootton ◽  
Z. Wu ◽  
K. Soong ◽  
I. V. Makasyuk ◽  
...  
Keyword(s):  
Damage Threshold ◽  
Laser Pulses ◽  
Critical Value ◽  
Fused Silica ◽  
Material Damage ◽  
Single Shot ◽  
Threshold Fluence ◽  
Intrinsic Parameter ◽  
Asymptotic Value ◽  
Extrinsic Parameters

We developed a systematic experimental method to demonstrate that damage threshold fluence (DTF) for fused silica changes with the number of femtosecond laser (800 nm, $65\pm 5~\text{fs}$, 10 Hz and 600 Hz) pulses. Based on the experimental data, we were able to develop a model which indicates that the change in DTF varies with the number of shots logarithmically up to a critical value. Above this value, DTF approaches an asymptotic value. Both DTF for a single shot and the asymptotic value as well as the critical value where this happens, are extrinsic parameters dependent on the configuration (repetition rate, pressure and geometry near or at the surface). These measurements indicate that the power of this dependence is an intrinsic parameter independent of the configuration.

Sign in / Sign up

Export Citation Format

Share Document