Improvement of GPS and GLONASS Positioning Accuracy by Multipath Mitigation Using Omnidirectional Infrared Camera

2011 ◽  
Vol 23 (6) ◽  
pp. 1125-1131 ◽  
Author(s):  
Mitsunori Kitamura ◽  
◽  
Taro Suzuki ◽  
Yoshiharu Amano ◽  
Takumi Hashizume
Keyword(s):  
Mobile Robots ◽  
Infrared Camera ◽  
Multipath Mitigation ◽  
Positioning Accuracy ◽  
Ir Camera ◽  
Multipath Error ◽  
Satellite Positioning ◽  
Positioning Technique ◽  
The Difference ◽  
Atmospheric Transmittance

This paper describes a precision positioning technique that can be applied to vehicles or mobile robots in urban or leafy environments. The availability of satellite positioning is currently expected to improve due to the presence of positioning satellites such as US GPS, Russia’s Glonass and Europe’s Galileo. Due to the serious multipath impact on positioning accuracy in urban or leafy areas, however, improvements in satellite positioning availability do not necessarily facilitate highprecision positioning. Our proposed technique mitigates the GPS and Glonass multipath using an omnidirectional infrared (IR) camera that can eliminate the need for invisible satellites using IR images. With an IR camera, the sky appears distinctively dark. This facilitates the detection of the borderline between the sky and surrounding buildings and foliage due to the difference in atmospheric transmittance between visible light and IR rays, since buildings and foliage appear white. The proposed technique can automatically and robustly mitigate the GPS and Glonass multipath by excluding invisible satellites. Positioning was evaluated with visible satellites, which have less multipath error and without using invisible satellites. Evaluation results confirmed the effectiveness of the proposed technique and the feasibility of its highly accurate positioning.

scholarly journals Sphere to Spheroid Comparisons

2006 ◽  
Vol 59 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Michael A. Earle
Keyword(s):  
Great Circle ◽  
Positioning Accuracy ◽  
The Earth ◽  
Satellite Positioning ◽  
The Difference ◽  
Great Circle Distance ◽  
Spheroidal Model

The notion of the earth as a perfect sphere has served navigators quite well over the centuries and it continues to provide a basis for instruction and practical navigation. Aside from the fact that modern navigators employ refined models of the earth such as the WGS84 ellipsoid, which together with satellite positioning gives unprecedented positioning accuracy, the question arises as to just how good are the spherical results for distance when compared to the results for distance obtained from the spheroidal model. In this document a comparison is made of great circle distance (GCD) on the sphere with great ellipse distance (GED) on the spheroid. This comparison is then repeated for rhumbline distances. In each case it is concluded that the difference in using the sphere when compared to the spheroid is near 0·5%.

scholarly journals Bi-Spectral Infrared Algorithm for Cloud Coverage over Oceans by the JEM-EUSO Mission Program

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6506
Author(s):  
David Santalices ◽  
Susana Briz ◽  
Antonio J. de Castro ◽  
Fernando López
Keyword(s):  
Brightness Temperature ◽  
Ad Hoc ◽  
Low Cost ◽  
Infrared Camera ◽  
Cosmic Ray ◽  
High Energy ◽  
Ir Camera ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Difference ◽  
Split Window Algorithm

The need to monitor specific areas for different applications requires high spatial and temporal resolution. This need has led to the proliferation of ad hoc systems on board nanosatellites, drones, etc. These systems require low cost, low power consumption, and low weight. The work we present follows this trend. Specifically, this article evaluates a method to determine the cloud map from the images provided by a simple bi-spectral infrared camera within the framework of JEM-EUSO (The Joint Experiment Missions-Extrem Universe Space Observatory). This program involves different experiments whose aim is determining properties of Ultra-High Energy Cosmic Ray (UHECR) via the detection of atmospheric fluorescence light. Since some of those projects use UV instruments on board space platforms, they require knowledge of the cloudiness state in the FoV of the instrument. For that reason, some systems will include an infrared (IR) camera. This study presents a test to generate a binary cloudiness mask (CM) over the ocean, employing bi-spectral IR data. The database is created from Moderate-Resolution Imaging Spectroradiometer (MODIS) data (bands 31 and 32). The CM is based on a split-window algorithm. It uses an estimation of the brightness temperature calculated from a statistical study of an IR images database along with an ancillary sea surface temperature. This statistical procedure to obtain the estimate of the brightness temperature is one of the novel contributions of this work. The difference between the measured and estimation of the brightness temperature determines whether a pixel is cover or clear. That classification requires defining several thresholds which depend on the scenarios. The procedure for determining those thresholds is also novel. Then, the results of the algorithm are compared with the MODIS CM. The agreement is above 90%. The performance of the proposed CM is similar to that of other studies. The validation also shows that cloud edges concentrate the vast majority of discrepancies with the MODIS CM. The relatively high accuracy of the algorithm is a relevant result for the JEM-EUSO program. Further work will combine the proposed algorithm with complementary studies in the framework of JEM-EUSO to reinforce the CM above the cloud edges.

Development of a Positioning Technique for an Urban Area Using Omnidirectional Infrared Camera and Aerial Survey Data

2008 ◽  
Vol 22 (6-7) ◽  
pp. 731-747 ◽  
Author(s):  
Jun-ichi Meguro ◽  
Taishi Murata ◽  
Yoshiharu Amano ◽  
Takumi Hasizume ◽  
Jun-ichi Takiguchi
Keyword(s):  
Urban Area ◽  
Survey Data ◽  
Infrared Camera ◽  
Aerial Survey ◽  
Positioning Technique

Characterization of Fouled Flat Sheet Membranes by Infrared Thermography

2014 ◽  
Author(s):  
Kennethrex O. Ndukaife ◽  
George Agbai Nnanna
Keyword(s):  
Surface Temperature ◽  
Infrared Thermography ◽  
Spectral Power ◽  
Membrane Surface ◽  
Infrared Camera ◽  
Feed Solution ◽  
Feed Concentration ◽  
Ir Camera ◽  
Measure Surface Temperature

An Infrared thermography (IRT) technique for characterization of fouling on membrane surface has been developed. The emitted spectral power from the fouled membrane is a function of emissivity and surface morphology. In this work, a FLIR A320 IR camera was used to measure surface temperature and emissivity. The surface temperature and the corresponding emissivity value of various areas on the fouled membrane surface is measured by the infrared camera and recorded alongside its thermogram. Different fouling experiments were performed using different concentrations of aluminum oxide nanoparticle mixed with deionized water as feed solution (333 ppm, 1833 ppm and 3333 ppm) so as to investigate the effect of feed concentration on the degree of fouling and thus its effect on the emissivity values measured on the membrane surfaces. Surface plots in 3D and Line plots are obtained for the measured emissivity values and thickness of the fouling deposit on the membrane surface respectively. The results indicate that the IRT technique is sensitive to changes that occur on the membrane surface due to deposition of contaminants on the membrane surface and that emissivity is a function of temperature, surface roughness and thickness of the specimen under investigation.

Multi-resolution Visual Positioning and Navigation Technique for Unmanned Aerial System Landing Assistance

2017 ◽  
Vol 70 (6) ◽  
pp. 1276-1292
Author(s):  
Chong Yu ◽  
Jiyuan Cai ◽  
Qingyu Chen
Keyword(s):  
Real World ◽  
State Of The Art ◽  
Unmanned Aerial System ◽  
Detection Accuracy ◽  
Relative Positioning ◽  
Positioning Accuracy ◽  
Visual Positioning ◽  
Positioning Technique ◽  
Technique Comparison ◽  
Resolution Simulation

To achieve more accurate navigation performance in the landing process, a multi-resolution visual positioning technique is proposed for landing assistance of an Unmanned Aerial System (UAS). This technique uses a captured image of an artificial landmark (e.g. barcode) to provide relative positioning information in the X, Y and Z axes, and yaw, roll and pitch orientations. A multi-resolution coding algorithm is designed to ensure the UAS will not lose the detection of the landing target due to limited visual angles or camera resolution. Simulation and real world experiments prove the performance of the proposed technique in positioning accuracy, detection accuracy, and navigation effect. Two types of UAS are used to verify the generalisation of the proposed technique. Comparison experiments to state-of-the-art techniques are also included with the results analysis.

scholarly journals Atmospheric Correction for Tower-Based Solar-Induced Chlorophyll Fluorescence Observations at O2-A Band

2019 ◽  
Vol 11 (3) ◽  
pp. 355 ◽  
Author(s):  
Xinjie Liu ◽  
Jian Guo ◽  
Jiaochan Hu ◽  
Liangyun Liu
Keyword(s):  
Chlorophyll Fluorescence ◽  
Atmospheric Correction ◽  
Field Measurements ◽  
Correction Method ◽  
Oxygen Absorption ◽  
Atmospheric Transmission ◽  
Absorption Bands ◽  
Transfer Path ◽  
The Difference ◽  
Atmospheric Transmittance

Solar-induced chlorophyll fluorescence (SIF) has been proven to be an efficient indicator of vegetation photosynthesis. To investigate the relationship between SIF and Gross Primary Productivity (GPP), tower-based continuous spectral observations coordinated with eddy covariance (EC) measurements are needed. As the strong absorption effect at the O2-A absorption bands has an obvious influence on SIF retrieval based on the Fraunhofer Line Discrimination (FLD) principle, atmospheric correction is required even for tower-based SIF observations made with a sensor tens of meters above the canopy. In this study, an operational and simple solution for atmospheric correction of tower-based SIF observations at the O2-A band is proposed. The aerosol optical depth (AOD) and radiative transfer path length (RTPL) are found to be the dominant factors influencing the upward and downward transmittances at the oxygen absorption band. Look-up tables (LUTs) are established to estimate the atmosphere transmittance using AOD and RTPL based on the MODerate resolution atmospheric TRANsmission 5 (MODTRAN 5) model simulations, and the AOD is estimated using the ratio of the downwelling irradiance at 790 nm to that at 660 nm (E790/E660). The influences of the temperature and pressure on the atmospheric transmittance are also compensated for using a corrector factor of RTPL based on an empirical equation. A series of field measurements were carried out to evaluate the performance of the atmospheric correction method for tower-based SIF observations. The difference between the SIF retrieved from tower-based and from ground-based observations decreased obviously after the atmospheric correction. The results indicate that the atmospheric correction method based on a LUT is efficient and also necessary for more accurate tower-based SIF retrieval, especially at the O2-A band.

Surface Temperature Field Statistics at an Air/Water Interface for Grid-Generated Sub-Surface Turbulence

2002 ◽  
Author(s):  
Karen A. Flack ◽  
Geoffrey B. Smith
Keyword(s):  
Surface Temperature ◽  
Infrared Camera ◽  
Temperature Fields ◽  
Interface Temperature ◽  
Water Interface ◽  
Bulk Fluid ◽  
Air Water Interface ◽  
Evaporative Convection ◽  
The Difference ◽  
Oscillation Frequencies

Surface temperature fields and statistics are presented for the case of sub-surface grid-generated turbulence impacting an air/water interface. Temperature measurements are obtained with an infrared camera, sensitive in the 3–5 micron wavelength range. Results indicate that increased grid oscillation frequencies, and shallower grid depths, lead to increased surface mixing, yielding lower values of RMS temperature. Non-dimensionalization of the RMS temperatures using the difference in the average surface and the bulk fluid temperatures, collapses the data obtained for different grid depths and oscillation frequencies. This scaling is related to the thermal boundary layer thickness. The results are compared to the baseline case of turbulence due to evaporative convection without an oscillating grid.

scholarly journals Estimation of Vertical Jump Height Using Nintendo Wii Remote IR Camera

2018 ◽  
Vol 72 ◽  
pp. 02004
Author(s):  
Bhanupol Klongratog ◽  
Warit Pengto ◽  
Todsaporn Wornkert ◽  
Anupong Srongprapa
Keyword(s):  
Coordinate System ◽  
Vertical Jump ◽  
Infrared Camera ◽  
Slow Motion ◽  
Basketball Players ◽  
Nintendo Wii ◽  
Ir Camera ◽  
Conservation Of Energy ◽  
Vertical Jump Height ◽  
Vertical Leap

In this article, we proposed to measure the heights of countermovement jumps which are recorded in term of vertical leap by using the Wii Remote infrared camera. According to the physical principles, positions of the movement were detected based on the rules regarding conservation of energy, motion under gravity, and coordinate system. The obtained results were compared with that of the slow-motion measurements. The experiment involved 30 basketball players whose jump results were slightly deviated from the vertical measurement of the coordinate system. Therefore, the results should be calibrated each time the new system is installed.

scholarly journals Variation of Static-PPP Positioning Accuracy Using GPS-Single Frequency Observations (Aswan, Egypt)

2017 ◽  
Vol 52 (2) ◽  
pp. 19-26 ◽  
Author(s):  
Ashraf Farah
Keyword(s):  
Precision Agriculture ◽  
Precise Point Positioning ◽  
Low Cost ◽  
High Accuracy ◽  
Single Frequency ◽  
Dual Frequency ◽  
Differential Gps ◽  
Positioning Accuracy ◽  
Comparable Accuracy ◽  
Positioning Technique

Abstract Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.

Assessment of wavelets analysis for carrier-phase multipath mitigationThis article is one of a series of papers published in this Special Issue on the theme GEODESY.

2009 ◽  
Vol 46 (8) ◽  
pp. 627-636
Author(s):  
Ahmed A. El-Ghazouly ◽  
Mohamed Elhabiby ◽  
Naser El-Sheimy
Keyword(s):  
Carrier Phase ◽  
Deformation Monitoring ◽  
Double Difference ◽  
Multipath Mitigation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Adaptive Wavelet ◽  
Multipath Error ◽  
Phase Measurements ◽  
Search Volume

In carrier-phase measurements, which are the most precise observations for Global Positioning System (GPS) relative positioning, multipath error is still a factor that interferes with achieving the desired accuracy. Various improvements in receiver and antenna technologies, as well as modeling strategies, have resulted in better ways of coping with this error source. However, errors caused by multipath can be as large as 5 cm, which is not an acceptable accuracy, especially in precise surveying applications like deformation monitoring. In this paper, a full assessment of different wavelets techniques that can be used in multipath mitigation is made to evaluate the optimum way of using wavelets to reduce or remove this type of error. Also, a new approach based on the wavelet detrending technique is introduced to remove carrier-phase multipath error in the measurement domain. To mitigate multipath, GPS double-difference observables are fed to an adaptive wavelet analysis procedure based on high- and low-pass filter decomposition with different levels of resolution. Consequently, the observable sequences are corrected; these corrected observables can then be used to reduce the ambiguity search volume during the initial float solution stage. Meanwhile, double-difference observations with multipath mitigation offer an efficient method for obtaining a better baseline solution.

Sign in / Sign up

Export Citation Format

Share Document