scholarly journals OPTIMIZING THE DISTRIBUTION OF TIE POINTS FOR THE BUNDLE ADJUSTMENT OF HRSC IMAGE MOSAICS

2017 ◽  
Vol XLII-3/W1 ◽  
pp. 15-22
Author(s):  
J. Bostelmann ◽  
U. Breitkopf ◽  
C. Heipke
Keyword(s):  
Computation Time ◽  
Grid Cell ◽  
Large Data ◽  
Optical Filters ◽  
Bundle Adjustment ◽  
Martian Surface ◽  
Terrain Model ◽  
Reference Information ◽  
Global Mapping ◽  
Line Scanner

For a systematic mapping of the Martian surface, the Mars Express orbiter is equipped with a multi-line scanner: Since the beginning of 2004 the High Resolution Stereo Camera (HRSC) regularly acquires long image strips. By now more than 4,000 strips covering nearly the whole planet are available. Due to the nine channels, each with different viewing direction, and partly with different optical filters, each strip provides 3D and color information and allows the generation of digital terrain models (DTMs) and orthophotos. <br><br> To map larger regions, neighboring HRSC strips can be combined to build DTM and orthophoto mosaics. The global mapping scheme Mars Chart 30 is used to define the extent of these mosaics. In order to avoid unreasonably large data volumes, each MC-30 tile is divided into two parts, combining about 90 strips each. To ensure a seamless fit of these strips, several radiometric and geometric corrections are applied in the photogrammetric process. A simultaneous bundle adjustment of all strips as a block is carried out to estimate their precise exterior orientation. Because size, position, resolution and image quality of the strips in these blocks are heterogeneous, also the quality and distribution of the tie points vary. In absence of ground control points, heights of a global terrain model are used as reference information, and for this task a regular distribution of these tie points is preferable. Besides, their total number should be limited because of computational reasons. <br><br> In this paper, we present an algorithm, which optimizes the distribution of tie points under these constraints. A large number of tie points used as input is reduced without affecting the geometric stability of the block by preserving connections between strips. This stability is achieved by using a regular grid in object space and discarding, for each grid cell, points which are redundant for the block adjustment. The set of tie points, filtered by the algorithm, shows a more homogenous distribution and is considerably smaller. Used for the block adjustment, it yields results of equal quality, with significantly shorter computation time. In this work, we present experiments with MC-30 half-tile blocks, which confirm our idea for reaching a stable and faster bundle adjustment. The described method is used for the systematic processing of HRSC data.

scholarly journals GLOBAL BUNDLE ADJUSTMENT WITH VARIABLE ORIENTATION POINT DISTANCE FOR PRECISE MARS EXPRESS ORBIT RECONSTRUCTION

2016 ◽  
Vol XLI-B4 ◽  
pp. 361-368
Author(s):  
J. Bostelmann ◽  
C. Heipke
Keyword(s):  
Image Data ◽  
Bundle Adjustment ◽  
New Method ◽  
Martian Surface ◽  
Exterior Orientation ◽  
Data Set ◽  
Point Distance ◽  
Line Scanner ◽  
Image Orientation

The photogrammetric bundle adjustment of line scanner image data requires a precise description of the time-dependent image orientation. For this task exterior orientation parameters of discrete points are used to model position and viewing direction of a camera trajectory via polynomials. This paper investigates the influence of the distance between these orientation points on the quality of trajectory modeling. A new method adapts the distance along the trajectory to the available image information. Compared to a constant distance as used previously, a better reconstruction of the exterior orientation is possible, especially when image quality changes within a strip. <br><br> In our research we use image strips of the High Resolution Stereo Camera (HRSC), taken to map the Martian surface. Several experiments on the global image data set have been carried out to investigate how the bundle adjustment improves the image orientation, if the new method is employed. For evaluation the forward intersection errors of 3D points derived from HRSC images, as well as their remaining height differences to the MOLA DTM are used. <br><br> In 13.5 % (515 of 3,828) of the image strips, taken during this ongoing mission over the last 12 years, high frequency image distortions were found. Bundle adjustment with a constant orientation point distance was able to reconstruct the orbit in 239 (46.4 %) cases. A variable orientation point distance increased this number to 507 (98.6 %).

scholarly journals GLOBAL BUNDLE ADJUSTMENT WITH VARIABLE ORIENTATION POINT DISTANCE FOR PRECISE MARS EXPRESS ORBIT RECONSTRUCTION

2016 ◽  
Vol XLI-B4 ◽  
pp. 361-368 ◽  
Author(s):  
J. Bostelmann ◽  
C. Heipke
Keyword(s):  
Image Data ◽  
Bundle Adjustment ◽  
New Method ◽  
Martian Surface ◽  
Exterior Orientation ◽  
Data Set ◽  
Point Distance ◽  
Line Scanner ◽  
Image Orientation

The photogrammetric bundle adjustment of line scanner image data requires a precise description of the time-dependent image orientation. For this task exterior orientation parameters of discrete points are used to model position and viewing direction of a camera trajectory via polynomials. This paper investigates the influence of the distance between these orientation points on the quality of trajectory modeling. A new method adapts the distance along the trajectory to the available image information. Compared to a constant distance as used previously, a better reconstruction of the exterior orientation is possible, especially when image quality changes within a strip. &lt;br&gt;&lt;br&gt; In our research we use image strips of the High Resolution Stereo Camera (HRSC), taken to map the Martian surface. Several experiments on the global image data set have been carried out to investigate how the bundle adjustment improves the image orientation, if the new method is employed. For evaluation the forward intersection errors of 3D points derived from HRSC images, as well as their remaining height differences to the MOLA DTM are used. &lt;br&gt;&lt;br&gt; In 13.5 % (515 of 3,828) of the image strips, taken during this ongoing mission over the last 12 years, high frequency image distortions were found. Bundle adjustment with a constant orientation point distance was able to reconstruct the orbit in 239 (46.4 %) cases. A variable orientation point distance increased this number to 507 (98.6 %).

scholarly journals Technical Note: Preliminary estimation of rockfall runout zones

2011 ◽  
Vol 11 (3) ◽  
pp. 819-828 ◽  
Author(s):  
M. Jaboyedoff ◽  
V. Labiouse
Keyword(s):  
Slope Angle ◽  
Digital Terrain Model ◽  
Grid Cell ◽  
Technical Note ◽  
Field Observations ◽  
Source Areas ◽  
Terrain Model ◽  
Digital Terrain ◽  
Energy Line ◽  
Potential Source

Abstract. Rockfall propagation areas can be determined using a simple geometric rule known as shadow angle or energy line method based on a simple Coulomb frictional model implemented in the CONEFALL computer program. Runout zones are estimated from a digital terrain model (DTM) and a grid file containing the cells representing rockfall potential source areas. The cells of the DTM that are lowest in altitude and located within a cone centered on a rockfall source cell belong to the potential propagation area associated with that grid cell. In addition, the CONEFALL method allows estimation of mean and maximum velocities and energies of blocks in the rockfall propagation areas. Previous studies indicate that the slope angle cone ranges from 27° to 37° depending on the assumptions made, i.e. slope morphology, probability of reaching a point, maximum run-out, field observations. Different solutions based on previous work and an example of an actual rockfall event are presented here.

Introducing xSub: A new portal for cross-national data on subnational violence

2019 ◽  
Vol 56 (4) ◽  
pp. 604-614 ◽  
Author(s):  
Yuri M Zhukov ◽  
Christian Davenport ◽  
Nadiya Kostyuk
Keyword(s):  
Grid Cell ◽  
Large Data ◽  
Political Conflict ◽  
Data Sources ◽  
National Data ◽  
Units Of Analysis ◽  
Disaggregated Data ◽  
Data Collections ◽  
The Impact ◽  
Cross National

Researchers today have access to an unprecedented amount of geo-referenced, disaggregated data on political conflict. Because these new data sources use disparate event typologies and units of analysis, findings are rarely comparable across studies. As a result, we are unable to answer basic questions like ‘what does conflict A tell us about conflict B?’ This article introduces xSub – a ‘database of databases’ for disaggregated research on political conflict ( www.x-sub.org ). xSub reduces barriers to comparative subnational research, by empowering researchers to quickly construct custom, analysis-ready datasets. xSub currently features subnational data on conflict in 156 countries, from 21 sources, including large data collections and data from individual scholars. To facilitate comparisons across countries and sources, xSub organizes these data into consistent event categories, actors, spatial units (country, province, district, grid cell, electoral constituency), and time units (year, month, week, and day). This article introduces xSub and illustrates its potential, by investigating the impact of repression on dissent across thousands of subnational datasets.

Simulated Radiance Profiles for Automating the Interpretation of Airborne Passive Multi-Spectral Infrared Images

2008 ◽  
Vol 62 (10) ◽  
pp. 1049-1059 ◽  
Author(s):  
Yusuf Sulub ◽  
Gary W. Small
Keyword(s):  
Simulation Model ◽  
Infrared Imaging ◽  
Imaging System ◽  
Piecewise Linear ◽  
Field Measurements ◽  
Optical Filters ◽  
Pure Component ◽  
Linear Discriminant ◽  
Pattern Recognition Methods ◽  
Line Scanner

Methodology is developed for simulating the radiance profiles acquired from airborne passive multispectral infrared imaging measurements of ground sources of volatile organic compounds (VOCs). The simulation model allows the superposition of pure-component laboratory spectra of VOCs onto spectral backgrounds that simulate those acquired during field measurements conducted with a downward-looking infrared line scanner mounted on an aircraft flying at an altitude of 2000–3000 ft (approximately 600–900 m). Wavelength selectivity in the line scanner is accomplished through the use of a multichannel Hg:Cd:Te detector with up to 16 integrated optical filters. These filters allow the detection of absorption and emission signatures of VOCs superimposed on the upwelling infrared background radiance within the instrumental field of view (FOV). By combining simulated radiance profiles containing analyte signatures with field-collected background signatures, supervised pattern recognition methods can be employed to train automated classifiers for use in detecting the signatures of VOCs during field measurements. The targeted application for this methodology is the use of the imaging system to detect releases of VOCs during emergency response scenarios. In the work described here, the simulation model is combined with piecewise linear discriminant analysis to build automated classifiers for detecting ethanol and methanol. Field data collected during controlled releases of ethanol, as well as during a methanol release from an industrial facility, are used to evaluate the methodology.

scholarly journals Spatially Distributed Characterization of Soil Dynamics Using Travel-Time Distributions

2016 ◽  
Author(s):  
Falk Heße ◽  
Matthias Zink ◽  
Rohini Kumar ◽  
Luis Samaniego ◽  
Sabine Attinger
Keyword(s):  
Travel Time ◽  
Potential Evapotranspiration ◽  
Grid Cell ◽  
Large Data ◽  
Data Sets ◽  
Travel Times ◽  
Spatially Distributed ◽  
Hydrological System ◽  
And Storage

Abstract. Travel-time distributions are a comprehensive tool for the characterization of hydrological system dynamics. Unlike streamflow hydrographs, they describe the movement and storage of water inside and through the hydrological system. Until recently, studies using such travel-time distributions have generally either been applied to simple (artificial toy) models or to real-world catchments using available time series, e.g. stable isotopes. Whereas the former are limited in their realism, the latter are limited in their use of available data sets. In our study, we employ a middle ground by using the mesoscale Hydrological Model (mHM) and apply it to a catchment in Central Germany. Being able to draw on multiple large data sets for calibration and verification, we generate a large array of spatially distributed states and fluxes. These hydrological outputs are then used to compute the travel-time distributions for every grid cell in the modeling domain. A statistical analysis shows the general soundness of the upscaling scheme employed in mHM and reveal precipitation, saturated soil moisture and potential evapotranspiration as important predictors for explaining the spatial heterogeneity of mean travel times. In addition, we demonstrate and discuss the high information content of mean travel times for characterization of internal hydrological processes.

scholarly journals ANALYZING A BLOCK OF HRSC IMAGE STRIPS FOR A SIMULTANEOUS BUNDLE ADJUSTMENT

2014 ◽  
Vol II-4 ◽  
pp. 15-20 ◽  
Author(s):  
J. Bostelmann ◽  
C. Heipke
Keyword(s):  
Three Dimensional ◽  
Automated Analysis ◽  
Processing Parameters ◽  
Bundle Adjustment ◽  
Martian Surface ◽  
Orientation Data ◽  
Digital Terrain ◽  
German Aerospace ◽  
Simultaneous Adjustment ◽  
Along Track

10 years ago the first European interplanetary mission Mars Express was launched and sent into orbit around Mars. One of the scientific instruments on board the orbiter is the High Resolution Stereo Camera (HRSC). This multi-line sensor with five panchromatic and four multispectral CCD lines was developed by the German Aerospace Center (DLR) for photogrammetric mapping purposes. It images the Martian surface with a resolution of up to 12 m per pixel, depending on the altitude. The along-track stereo capability of the camera delivers image strips with three-dimensional information, which cover nearly the whole planet. For a derivation of more accurate digital terrain models and orthoimages the orientation data of the camera is improved via bundle adjustment. <br><br> To map larger regions overlapping image strips can be used to form photogrammetric blocks, thus allowing a simultaneous adjustment of the different strips. Compared to the adjustment of individual strips, an adjustment of the entire block reduces not only local, but also regional inconsistencies in the data. With the growing number of HRSC image strips in this ongoing mission, number, size and complexity of potential blocks increases. To cope with these data a method for a semi-automated analysis, selection and combination of suitable strips for the design of more accurate and reliable blocks has been developed. The method takes the inhomogeneity of the HRSC data into account by adapting the processing parameters, if necessary for each strip.

scholarly journals Optimized memory model for hadoop map reduce framework

2019 ◽  
Vol 9 (5) ◽  
pp. 4396
Author(s):  
Archana Bhaskar ◽  
Rajeev Ranjan
Keyword(s):  
Service Provider ◽  
Service Level Agreement ◽  
Computation Time ◽  
Large Data ◽  
Cloud Service ◽  
Map Reduce ◽  
Memory Optimization ◽  
Process Data ◽  
Cloud Service Provider ◽  
Microsoft Azure

Map Reduce is the preferred computing framework used in large data analysis and processing applications. Hadoop is a widely used Map Reduce framework across different community due to its open source nature. Cloud service provider such as Microsoft azure HDInsight offers resources to its customer and only pays for their use. However, the critical challenges of cloud service provider is to meet user task Service level agreement (SLA) requirement (task deadline). Currently, the onus is on client to compute the amount of resource required to run a job on cloud. This work present a novel memory optimization model for Hadoop Map Reduce framework namely MOHMR (Optimized Hadoop Map Reduce) to process data in real-time and utilize system resource efficiently. The MOHMR present accurate model to compute job memory optimization and also present a model to provision the amount of cloud resource required to meet task deadline. The MOHMR first build a profile for each job and computes memory optimization time of job using greedy approach. Experiment are conducted on Microsoft Azure HDInsight cloud platform considering different application such as text computing and bioinformatics application to evaluate performance of MOHMR of over existing model shows significant performance improvement in terms of computation time. Experiment are conducted on Microsoft Azure HDInsight cloud. Overall, good correlation is reported between practical memory optimization values and theoretical memory optimization values.

scholarly journals Kriging Method Optimization for the Process of DTM Creation Based on Huge Data Sets Obtained from MBESs

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 433 ◽  
Author(s):  
Maleika Wojciech
Keyword(s):  
Spatial Data ◽  
Moving Average ◽  
Digital Terrain Model ◽  
Computation Time ◽  
Fixed Number ◽  
Kriging Interpolation ◽  
Computational Time ◽  
Kriging Method ◽  
Terrain Model ◽  
Digital Terrain

The paper presents an optimized method of digital terrain model (DTM) estimation based on modified kriging interpolation. Many methods are used for digital terrain model creation; the most popular methods are: inverse distance weighing, nearest neighbour, moving average, and kriging. The latter is often considered to be one of the best methods for interpolation of non-uniform spatial data, but the good results with respect to model’s accuracy come at the price of very long computational time. In this study, the optimization of the kriging method was performed for the purpose of seabed DTM creation based on millions of measurement points obtained from a multibeam echosounder device (MBES). The purpose of the optimization was to significantly decrease computation time, while maintaining the highest possible accuracy of created model. Several variants of kriging method were analysed (depending on search radius, minimum of required points, fixed number of points, and used smoothing method). The analysis resulted in a proposed optimization of the kriging method, utilizing a new technique of neighbouring points selection throughout the interpolation process (named “growing radius”). Experimental results proved the new kriging method to have significant advantages when applied to DTM estimation.

Control Design for Automated Vehicle Emergency Safe Stop System Based on Differential Dynamic Programming

2020 ◽  
Author(s):  
Lisheng Yang ◽  
Tomonari Furukawa ◽  
Lei Zuo ◽  
Zachary Doerzaph
Keyword(s):  
Dynamic Programming ◽  
Real Time ◽  
Control Algorithm ◽  
Computation Time ◽  
Grid Cell ◽  
System Control ◽  
Real Time Control ◽  
Differential Dynamic Programming ◽  
Time Control ◽  
Emergency Stop

Abstract This paper presents the control algorithm and system design for a newly proposed automated emergency stop system, which aims to navigate the vehicle out of its travel lane to a safe road-side location when an emergency (e.g. driver fails to take control during fallback of the Dynamic Driving Task) occurs. To address the unique requirements of such a system, control techniques based on differential dynamic programming are developed. Optimal control sequence computation is broken down into step-by-step quadratic optimization and solved iteratively. Control constraints are addressed efficiently by a tailored Projected-Newton algorithm. The iterative control algorithm is then integrated into a real-time control system which considers both computation delay and modeling errors. The system employs a novel grid-based storage structure for recording all acceptable control commands computed within the iteration and uses a high frequency estimator for self-localization. During operation, the real-time control thread will extract commands from the grid cell corresponding to current states. Simulation results show strong potential of the proposed system for addressing the engineering challenges of the automated emergency stop function. The robustness of the system in presence of computation time delay and modelling errors is also demonstrated.

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