scholarly journals Masked Correlation for Improvement of 2D Glacier Motion Estimation Based on Terrasar-x Imagery

2014 ◽  
Vol II-7 ◽  
pp. 9-13
Author(s):  
L. Fang ◽  
U. Stilla
Keyword(s):  
High Resolution ◽  
Motion Estimation ◽  
Cross Correlation ◽  
Correlation Method ◽  
Correlation Technique ◽  
Binary Mask ◽  
Normalized Cross Correlation ◽  
The Law ◽  
Cross Correlation Technique ◽  
Glacier Motion

In this paper, the impacts of the non-glacier information in the template window used in cross-correlation calculation for 2D motion estimation of glaciers are discussed and illustrated by the example of the Taku glacier, which is the biggest glacier in the Juneau Icefield, Alaska. For this, the glacier motion maps are extracted by the traditional normalized cross-correlation technique and the masked cross-correlation method, which uses a manually generated binary mask to threshold the non-glacier pixels, based on geocoded high resolution TerraSAR-X images. Based on the comparison of the different results, it was found that without the disturbing information (e.g., mountain, water) the accuracy of the cross-correlation of sequential patches in masked cross-correlation method is improved and the estimation results are much more reasonable, which respect the law that glacier flows like a river with higher velocity in the middle and than that in the sides.

scholarly journals Comparing C- and L-band SAR images for sea ice motion estimation

2015 ◽  
Vol 9 (1) ◽  
pp. 357-366 ◽  
Author(s):  
J. Lehtiranta ◽  
S. Siiriä ◽  
J. Karvonen
Keyword(s):  
Motion Estimation ◽  
Sea Ice ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Sar Images ◽  
L Band ◽  
The Baltic ◽  
Cross Correlation Technique ◽  
Multiyear Ice ◽  
Band Image

Abstract. Pairs of consecutive C-band synthetic-aperture radar (SAR) images are routinely used for sea ice motion estimation. The L-band radar has a fundamentally different character, as its longer wavelength penetrates deeper into sea ice. L-band SAR provides information on the seasonal sea ice inner structure in addition to the surface roughness that dominates C-band images. This is especially useful in the Baltic Sea, which lacks multiyear ice and icebergs, known to be confusing targets for L-band sea ice classification. In this work, L-band SAR images are investigated for sea ice motion estimation using the well-established maximal cross-correlation (MCC) approach. This work provides the first comparison of L-band and C-band SAR images for the purpose of motion estimation. The cross-correlation calculations are hardware accelerated using new OpenCL-based source code, which is made available through the author's web site. It is found that L-band images are preferable for motion estimation over C-band images. It is also shown that motion estimation is possible between a C-band and an L-band image using the maximal cross-correlation technique.

scholarly journals ASSAS: An automatic smart students attendance system based on normalized cross-correlation

2021 ◽  
Vol 10 (2) ◽  
pp. 732-741
Author(s):  
Ruaa H. Ali Al-Mallah ◽  
Dheyaa Alhelal ◽  
Razan Abdulhammed
Keyword(s):  
Image Processing ◽  
Face Recognition ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Human Being ◽  
Roll Call ◽  
Student Attendance ◽  
Normalized Cross Correlation ◽  
Two Phases ◽  
Cross Correlation Technique

A smart student attendance system (SSAS) is presented in this paper. The system is divided into two phases: hardware and software. The Hardware phase is implemented based on Arduino's camera while the software phase is achieved by using image processing with face recognition depended on the cross-correlation technique. In comparison with traditional attendance systems, roll call, and sign-in sheet, the proposed system is faster and more reliable (because there is no action needed by a human being who by its nature makes mistakes). At the same time, it is cheaper when compared with other automatic attendance systems. The proposed system provides a faster, cheaper and reachable system for an automatic smart student attendance that monitors and generates attendance report automatically.

scholarly journals Investigations on the Coregistration of Sentinel-1 TOPS with the Conventional Cross-Correlation Technique

2018 ◽  
Vol 10 (9) ◽  
pp. 1405 ◽  
Author(s):  
Yuxiao Qin ◽  
Daniele Perissin ◽  
Jing Bai
Keyword(s):  
Cross Correlation ◽  
Phase Error ◽  
Impulse Response Function ◽  
Correlation Method ◽  
Correlation Technique ◽  
Geometrical Approach ◽  
Rigid Transformation ◽  
Interferometric Phase ◽  
The Cross ◽  
Cross Correlation Technique

In Sentinel-1 TOPS mode, the antenna sweeps in the azimuth direction for the purpose of illuminating the targets with the entire azimuth antenna pattern (AAP). This azimuth sweeping introduces an extra high-frequency Doppler term into the impulse response function (IRF), which poses a more strict coregistration accuracy for the interferometric purpose. A 1/1000 pixel coregistration accuracy is required for the interferometric phase error to be negligible, and the enhanced spectral diversity (ESD) method is applied for achieving such accuracy. However, since ESD derives miscoregistration from cross-interferometric phase, and phase is always wrapped to [ − π , π ) , an initial coregistration method with enough accuracy is required to resolve the phase ambiguity in ESD. The mainstream for initial coregistration that meets this requirement is the geometrical approach, which accuracy mainly depends on the accuracy of orbits. In this article, the authors propose to investigate the feasibility of using the conventional coregistration approach, namely the cross-correlation-and-rigid-transformation, as the initial coregistration method. The aim is to quantify the coregistration accuracy for cross-correlation-and-rigid-transformation using the Cramér-Rao lower bound (CRLB) and determine whether this method could eventually help to resolve the phase ambiguities of ESD. In addition, we studied the feasibility and robustness of the cross-correlation plus ESD under different conditions. For validation, we checked whether the cross-correlation plus ESD approach could reach the same coregistration accuracy as geometrical plus ESD approach. In general, for large areas with enough coherence and little topography variance, the cross-correlation method could be used as an alternative to the geometrical approach. The interferogram from the two different approaches (with ESD applied afterward) shows a negligible difference under such circumstances.

scholarly journals Estimation of large-scale sea-ice motion from SSM/I 85.5 GHz imagery

1997 ◽  
Vol 25 ◽  
pp. 305-311 ◽  
Author(s):  
Tom A. Agnew ◽  
Hao Le ◽  
Tom Hirose
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Correlation Method ◽  
Arctic Basin ◽  
Canada Basin ◽  
Correlation Technique ◽  
Microwave Imager ◽  
Automated Technique ◽  
Surface Ice ◽  
Cross Correlation Technique

This paper describes the application of an automated cross-correlation technique to pairs of 85.5 GHz Special Sensor Microwave Imager (SSM/I) images to obtain ice motion over the entire Arctic Basin for a contiguous two month period between December 1993 and January 1994. Although the surface ice information in the imagery is coarse and noisy, the area cross-correlation method is quite successful in picking up ice-motion information. The accuracy of 85.5 GHz SSM/I derived ice motions is evaluated by comparing results with Arctic buoy drift. Over 390 comparisons with buoy-drift estimates of ice displacement were made with an overall correlation of 0.75 and an average vector magnitude error in ice velocity of 3.5 km d−1. The main difficulty with the automated technique is the tendency to overestimate ice displacement compared to buoy data by about 14%. Two detailed examples of ice motion are presented. The first occurred in December 1993, when a major westward shift in the ice pack took place in the Canada Basin and opened up a very large lead off Banks and Prince Patrick Islands. The second example occurred in January 1994, when an intense anticyclone over the Canada Basin produced a strong Beaufort Gyre.

scholarly journals Speckle Cross-Correlation Method in Measuring Fine Surface Displacements

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
M. Bahrawi ◽  
N. Farid ◽  
M. Abdel-Hady
Keyword(s):  
Cross Correlation ◽  
Correlation Method ◽  
Industrial Applications ◽  
Correlation Technique ◽  
Surface Displacements ◽  
Speckle Patterns ◽  
The Cross ◽  
And Performance ◽  
The Stability ◽  
Cross Correlation Technique

Industrial applications need regular testing for the lifetime, movement, strength, and performance of manufacturing machines during production process. Since speckle photography is a simple economic technique, it is used in investigating object response under mechanical and thermal effects depending on the movement of the speckle patterns with respect to the deformation strength and direction. In the present work, the cross-correlation technique is used to analyze the speckle patterns by iterative method to define both values and directions of rigid body translation and expansion. In order to check the accuracy of the cross-correlation technique, the results are compared with the displacement values given by analyzing the Young's interference fringes resulted from the Fourier transformation of the speckle patterns. This noncontact technique is found to be accurate and informative depending on the stability and sensitivity of the optical system. This method of measurement is an effective tool in studying the hard cases of objects and machines under various effects.

scholarly journals Estimation of Large-Scale Sea-Ice Motion from SSM/I 85.5 GHz Imagery

1997 ◽  
Vol 25 ◽  
pp. 305-311 ◽  
Author(s):  
Tom A. Agnew ◽  
Hao Le ◽  
Tom Hirose
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Correlation Method ◽  
Arctic Basin ◽  
Canada Basin ◽  
Correlation Technique ◽  
Microwave Imager ◽  
Automated Technique ◽  
Surface Ice ◽  
Cross Correlation Technique

This paper describes the application of an automated cross-correlation technique to pairs of 85.5 GHz Special Sensor Microwave Imager (SSM/I) images to obtain Ice motion over the entire Arctic Basin for a contiguous two month period between December 1993 and January 1994. Although the surface ice information in the imagery is coarse and noisy, the area cross-correlation method is quite successful in picking up ice-motion information. The accuracy of 85.5 GHz SSM/I derived ice motions is evaluated by comparing results with Arctic buoy drift. Over 390 comparisons with buoy-drift estimates of ice displacement were made with an overall correlation of 0.75 and an average vector magnitude error in ice velocity of 3.5 km d−1. The main difficulty with the automated technique is the tendency to overestimate ice displacement compared to buoy data by about 14%. Two detailed examples of ice motion are presented. The first occurred in December 1993, when a major westward shift in the ice pack took place in the Canada Basin and opened up a very large lead off Banks and Prince Patrick Islands. The second example occurred in January 1994, when an intense anticyclone over the Canada Basin produced a strong Beaufort Gyre.

scholarly journals Comparing C- and L-band SAR images for sea ice motion estimation

2014 ◽  
Vol 8 (3) ◽  
pp. 2721-2757
Author(s):  
J. Lehtiranta ◽  
S. Siiriä ◽  
J. Karvonen
Keyword(s):  
Motion Estimation ◽  
Sea Ice ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Sar Images ◽  
L Band ◽  
Sar Imagery ◽  
The Baltic ◽  
Cross Correlation Technique ◽  
Multiyear Ice

Abstract. Pairs of consecutive C-band SAR images are routinely used for sea ice motion estimation. In addition to the surface roughness L-band SAR imagery provides information of the seasonal sea ice inner structure, which is especially useful in the Baltic Sea lacking multiyear ice and icebergs. In this work, L-band SAR images are investigated for sea ice motion estimation using the well-established maximal cross-correlation approach. This work provides the first comparison of L-band and C-band SAR images for the purpose of motion estimation. The cross-correlation calculations are hardware accelerated using new OpenCL-based source code, which is made available through the author's web site. It is found that L-band images are preferable for motion estimation over C-band images. It is also shown that motion estimation is possible between a C-band and an L-band image using the maximal cross-correlation technique.

Determination of Atomic and Molecular Excited-State Lifetimes Using an Optoelectronic Cross-Correlation Method

1982 ◽  
Vol 36 (2) ◽  
pp. 92-99 ◽  
Author(s):  
R. E. Russo ◽  
G. M. Hieftje
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Cross Correlation ◽  
Correlation Method ◽  
Correlation Technique ◽  
Atomic Fluorescence ◽  
Excited State Lifetimes ◽  
Cross Correlation Technique ◽  
Molecular Excited State

A new optoelectronic cross-correlation technique has been used to measure excited-state lifetimes of several organic fluorophores in solution and of sodium atoms in both air-acetylene and methane-air flames. Capable of time resolution in the picosecond range, the new method was validated by the excellent agreement between measured and literature values for fluorescence lifetimes of the organic species. Lifetime values for Na atoms in flames are among the most precise ever reported and agree closely with values calculated from the known flame gas composition, temperature, and the quenching cross-sections of the two dominant quenching species in the flame, N2 and CO2. From the Na excited-state lifetimes (0.72 ± 0.07 ns for air-acetylene and 0.48 ± 0.08 ns for methane-air flames), quantum efficiencies for atomic fluorescence were calculated.

scholarly journals The emergence of the red sequence at z~2 seen through galaxy clustering in the UKIDSS UDS

2012 ◽  
Vol 8 (S295) ◽  
pp. 105-108
Author(s):  
William G. Hartley ◽  
Omar Almaini ◽  
Alice Mortlock ◽  
Chris Conselice ◽  
Keyword(s):  
Dark Matter ◽  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Dark Matter Halos ◽  
Star Forming ◽  
Deep Survey ◽  
Cross Correlation Technique ◽  
Infrared Survey

AbstractWe use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the clustering for passive galaxies at z > 2, which we achieve using a cross-correlation technique. We find that passive galaxies are the most strongly clustered, typically hosted by massive dark matter halos with Mhalo > 1013 M⊙ irrespective of redshift or stellar mass. Our findings are consistent with models in which a critical halo mass determines the transition from star-forming to passive galaxies.

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