scholarly journals BUNDLE BLOCK ADJUSTMENT WITH CONSTRAINED RELATIVE ORIENTATIONS

2020 ◽  
Vol V-2-2020 ◽  
pp. 49-55
Author(s):  
E. Maset ◽  
L. Magri ◽  
I. Toschi ◽  
A. Fusiello
Keyword(s):  
Empirical Study ◽  
Experimental Evidence ◽  
Jacobian Matrix ◽  
Relative Orientation ◽  
Bundle Adjustment ◽  
Computational Load ◽  
Camera Systems ◽  
Bundle Block Adjustment ◽  
First Time

Abstract. This paper deals with bundle adjustment with constrained cameras, i.e. where the orientation of certain cameras is expressed relatively to others, and these relative orientations are part of the unknowns. Despite the remarkable interest for oblique multi-camera systems, an empirical study on the effect of enforcing relative orientation constraints in bundle adjustment is still missing. We provide experimental evidence that indeed these constraints improve the accuracy of the results, while reducing the computational load as well. Moreover, we report for the first time in the literature the complete derivation of the Jacobian matrix for bundle adjustment with constrained cameras, to foster other implementations.

scholarly journals EXPLOITING MULTI-CAMERA CONSTRAINTS WITHIN BUNDLE BLOCK ADJUSTMENT: AN EXPERIMENTAL COMPARISON

2021 ◽  
Vol XLIII-B2-2021 ◽  
pp. 33-38
Author(s):  
E. Maset ◽  
E. Rupnik ◽  
M. Pierrot-Deseilligny ◽  
F. Remondino ◽  
A. Fusiello
Keyword(s):  
Relative Orientation ◽  
Computational Time ◽  
Experimental Comparison ◽  
Internal Constraint ◽  
Camera Systems ◽  
Bundle Block Adjustment ◽  
Improve Accuracy ◽  
Processing Algorithms

Abstract. The growing deployment of multi-head camera systems encouraged the emergence of specific processing algorithms, able to face the challenges posed by slanted view geometry. Such multi-camera systems are rigidly tied by their manufacturers hence the exploitation of this internal constraint should be further exploited. Several approaches have been proposed to deal with orientation constraints, with the aim of reducing the number of unknowns, computational time and possibly improve the accuracy. In this paper we compare the results provided by publicly available implementations in order to further investigate the advantages of enforcing relative orientation constraints for aerial and terrestrial triangulation of multi-head camera systems. Data from a Leica CityMapper and a Stereopolis-Ladybug are considered, reporting how constrained solution can improve accuracy with respect to traditional (unconstrained) bundle block adjustment solutions.

scholarly journals TOWARDS THE INFLUENCE OF A CAR WINDSHIELD ON DEPTH CALCULATION WITH A STEREO CAMERA SYSTEM

2016 ◽  
Vol XLI-B5 ◽  
pp. 461-468
Author(s):  
A. Hanel ◽  
L. Hoegner ◽  
U. Stilla
Keyword(s):  
Road Safety ◽  
Standard Procedure ◽  
Relative Orientation ◽  
Bundle Adjustment ◽  
Camera System ◽  
Stereo Camera ◽  
Camera Systems ◽  
Road Users ◽  
The Difference ◽  
Planar Calibration

Stereo camera systems in cars are often used to estimate the distance of other road users from the car. This information is important to improve road safety. Such camera systems are typically mounted behind the windshield of the car. In this contribution, the influence of the windshield on the estimated distance values is analyzed. An offline stereo camera calibration is performed with a moving planar calibration target. In a standard procedure bundle adjustment, the relative orientation of the cameras is estimated. The calibration is performed for the identical stereo camera system with and without a windshield in between. The base lengths are derived from the relative orientation in both cases and are compared. Distance values are calculated and analyzed. It can be shown, that the difference of the base length values in the two cases is highly significant. Resulting effects on the distance calculation up to a half meter occur.

scholarly journals ON SCALE DEFINITION WITHIN CALIBRATION OF MULTI-CAMERA SYSTEMS IN MULTIMEDIA PHOTOGRAMMETRY

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 93-100 ◽  
Author(s):  
O. Kahmen ◽  
R. Rofallski ◽  
N. Conen ◽  
T. Luhmann
Keyword(s):  
Relative Orientation ◽  
Bundle Adjustment ◽  
Object Space ◽  
Implicit Form ◽  
Camera Systems ◽  
Systematic Effects ◽  
Synthetic Datasets ◽  
Orientation Parameters ◽  
Standard Software ◽  
Implicit Modelling

<p><strong>Abstract.</strong> In multimedia photogrammetry, multi-camera systems often provide scale by a calibrated relative orientation. Camera calibration via bundle adjustment is a well-established standard procedure in single-medium photogrammetry. When using standard software and applying the collinearity equations in multimedia photogrammetry, the refractive interfaces are modelled in an implicit form. This contribution analyses different calibration strategies for bundle-invariant interfaces. To evaluate the effects of implicitly modelling the refractive effects within a bundle adjustment, synthetic datasets are simulated. Contrary to many publications, systematic effects of the exterior orientations can be verified with simulated data. The behaviour of interior, exterior and relative orientation parameters is analysed using error-free synthetic datasets. The relative orientation of a stereo camera shows systematic effects, when the angle of convergence varies and when the synthetic interface is set up at different distances to the camera. It becomes clear, that in most cases the implicit modelling is not suitable for multimedia photogrammetry. An explicit modelling of the refractive interfaces is implemented into a bundle adjustment. This strict model is analysed and compared with the implicit form regarding systematic effects in orientation parameters as well as errors in object space. In a real experiment, the discrepancies between the implicit form using standard software and the explicit modelling using our own implementation are quantified. It is highly advisable to model the interfaces strictly, since the implicit modelling might lead to relevant errors in object space.</p>

scholarly journals TOWARDS THE INFLUENCE OF A CAR WINDSHIELD ON DEPTH CALCULATION WITH A STEREO CAMERA SYSTEM

2016 ◽  
Vol XLI-B5 ◽  
pp. 461-468 ◽  
Author(s):  
A. Hanel ◽  
L. Hoegner ◽  
U. Stilla
Keyword(s):  
Road Safety ◽  
Standard Procedure ◽  
Relative Orientation ◽  
Bundle Adjustment ◽  
Camera System ◽  
Stereo Camera ◽  
Camera Systems ◽  
Road Users ◽  
The Difference ◽  
Planar Calibration

Stereo camera systems in cars are often used to estimate the distance of other road users from the car. This information is important to improve road safety. Such camera systems are typically mounted behind the windshield of the car. In this contribution, the influence of the windshield on the estimated distance values is analyzed. An offline stereo camera calibration is performed with a moving planar calibration target. In a standard procedure bundle adjustment, the relative orientation of the cameras is estimated. The calibration is performed for the identical stereo camera system with and without a windshield in between. The base lengths are derived from the relative orientation in both cases and are compared. Distance values are calculated and analyzed. It can be shown, that the difference of the base length values in the two cases is highly significant. Resulting effects on the distance calculation up to a half meter occur.

scholarly journals Literatuurgeschiedschrijving én empirische literatuurwetenschap?

1970 ◽  
Vol 57 ◽  
pp. 21-35
Author(s):  
Daan Vandenhaute
Keyword(s):  
Empirical Study ◽  
Empirical Research ◽  
Theoretical Framework ◽  
Empirical Approach ◽  
First Time

The empirical study of literature might be tolerated as a discipline, withinliterary studies it remains an unknown, peripheral possibility, that has to dealwith a lot of scepticism and ignorance. Often it is associated with sheer quantitativeresearch, only focusing, moreover, on the contemporary. In this articleI try to show that the empirical approach also can be applied for the study ofliterary history, with attention paid to qualitative aspects. I demonstrate thisby means of empirical research I have done into the Swedish first time poetsof the 1970s. I point out that the empirical study of literature is conceived ofas a methodology that is applied within a specific theoretical framework, thesystemic study of literature.

scholarly journals ORIENTATION OF OBLIQUE AIRBORNE IMAGE SETS – EXPERIENCES FROM THE ISPRS/EUROSDR BENCHMARK ON MULTI-PLATFORM PHOTOGRAMMETRY

2016 ◽  
Vol XLI-B1 ◽  
pp. 185-191
Author(s):  
M. Gerke ◽  
F. Nex ◽  
F. Remondino ◽  
K. Jacobsen ◽  
J. Kremer ◽  
...  
Keyword(s):  
Digital Camera ◽  
Research Problem ◽  
Bundle Adjustment ◽  
Random Errors ◽  
Interest Points ◽  
Image Block ◽  
Point Matching ◽  
Camera Systems ◽  
Oblique Images ◽  
Image Orientation

During the last decade the use of airborne multi camera systems increased significantly. The development in digital camera technology allows mounting several mid- or small-format cameras efficiently onto one platform and thus enables image capture under different angles. Those oblique images turn out to be interesting for a number of applications since lateral parts of elevated objects, like buildings or trees, are visible. However, occlusion or illumination differences might challenge image processing. From an image orientation point of view those multi-camera systems bring the advantage of a better ray intersection geometry compared to nadir-only image blocks. On the other hand, varying scale, occlusion and atmospheric influences which are difficult to model impose problems to the image matching and bundle adjustment tasks. In order to understand current limitations of image orientation approaches and the influence of different parameters such as image overlap or GCP distribution, a commonly available dataset was released. The originally captured data comprises of a state-of-the-art image block with very high overlap, but in the first stage of the so-called ISPRS/EUROSDR benchmark on multi-platform photogrammetry only a reduced set of images was released. In this paper some first results obtained with this dataset are presented. They refer to different aspects like tie point matching across the viewing directions, influence of the oblique images onto the bundle adjustment, the role of image overlap and GCP distribution. As far as the tie point matching is concerned we observed that matching of overlapping images pointing to the same cardinal direction, or between nadir and oblique views in general is quite successful. Due to the quite different perspective between images of different viewing directions the standard tie point matching, for instance based on interest points does not work well. How to address occlusion and ambiguities due to different views onto objects is clearly a non-solved research problem so far. In our experiments we also confirm that the obtainable height accuracy is better when all images are used in bundle block adjustment. This was also shown in other research before and is confirmed here. Not surprisingly, the large overlap of 80/80% provides much better object space accuracy – random errors seem to be about 2-3fold smaller compared to the 60/60% overlap. A comparison of different software approaches shows that newly emerged commercial packages, initially intended to work with small frame image blocks, do perform very well.

Analysing the image of Abu Dhabi and Dubai as tourism destinations – The perception of first-time visitors from Germany

2017 ◽  
Vol 19 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Hanno M Martens ◽  
Dirk Reiser
Keyword(s):  
Middle East ◽  
Empirical Study ◽  
Tourism Development ◽  
Destination Image ◽  
Abu Dhabi ◽  
Environmentally Conscious ◽  
The World ◽  
Tourism Destinations ◽  
Similar Basis ◽  
First Time

The Middle East is one of the fastest growing tourism regions in the world. Especially Dubai (since the 1980s) and Abu Dhabi (since the 1990s) have invested heavily in tourism development to firstly enhance their recognition as international destinations and secondly to diversify their economies away from the oil production. Surprisingly, there is a lack of academic published articles on those two emirates’ international destination image. This paper attempts to fill this gap by studying and comparing the images of Abu Dhabi and Dubai amongst potential first-time visitors from one of their main source markets – Germany. An empirical study amongst 300 respondents from North-Rhine Westphalia, Germany, was conducted to reveal the cognitive image attributes of Dubai and Abu Dhabi for non-visitors. Despite both places having a similar basis for destination development, their images differ. Thus, Abu Dhabi and Dubai are not seen as competitors on the tourism market, instead they could even increase the mutual benefits through highlighting specific images more distinctly. Further, the research identified a missing fit between the desired tourism destination image for both destinations and the perceived destination image. This is especially significant for the aspect of sustainability, which both emirates try to promote. Potential tourists rather perceive both emirates as unsustainable and not environmentally conscious.

scholarly journals Cycle-CNN for Colorization towards Real Monochrome-Color Camera Systems

2020 ◽  
Vol 34 (07) ◽  
pp. 10721-10728
Author(s):  
Xuan Dong ◽  
Weixin Li ◽  
Xiaojie Wang ◽  
Yunhong Wang
Keyword(s):  
Color Image ◽  
Ground Truth ◽  
Real Data ◽  
Color Information ◽  
The Real ◽  
Gray Image ◽  
Camera Systems ◽  
Structure Similarity ◽  
First Time ◽  
Color Map

Colorization in monochrome-color camera systems aims to colorize the gray image IG from the monochrome camera using the color image RC from the color camera as reference. Since monochrome cameras have better imaging quality than color cameras, the colorization can help obtain higher quality color images. Related learning based methods usually simulate the monochrome-color camera systems to generate the synthesized data for training, due to the lack of ground-truth color information of the gray image in the real data. However, the methods that are trained relying on the synthesized data may get poor results when colorizing real data, because the synthesized data may deviate from the real data. We present a new CNN model, named cycle CNN, which can directly use the real data from monochrome-color camera systems for training. In detail, we use the colorization CNN model to do the colorization twice. First, we colorize IG using RC as reference to obtain the first-time colorization result IC. Second, we colorize the de-colored map of RC, i.e. RG, using the first-time colorization result IC as reference to obtain the second-time colorization result R′C. In this way, for the second-time colorization result R′C, we use the original color map RC as ground-truth and introduce the cycle consistency loss to push R′C ≈ RC. Also, for the first-time colorization result IC, we propose a structure similarity loss to encourage the luminance maps between IG and IC to have similar structures. In addition, we introduce a spatial smoothness loss within the colorization CNN model to encourage spatial smoothness of the colorization result. Combining all these losses, we could train the colorization CNN model using the real data in the absence of the ground-truth color information of IG. Experimental results show that we can outperform related methods largely for colorizing real data.

Der Kronzeuge im Strafgesetzbuch

2019 ◽  
Author(s):  
Stephan Christoph
Keyword(s):  
Empirical Study ◽  
Online Survey ◽  
Criminal Code ◽  
Legal Norm ◽  
Court Decisions ◽  
Student Survey ◽  
Practical Application ◽  
Legal Concept ◽  
The Core ◽  
First Time

Since 2009, the German criminal code has contained a far-reaching accomplice evidence rule (“Kronzeugenregelung“) in its sec. 46b. In his book, the author deals intensively with different aspects of this recent legal norm. He concentrates both on practical and on dogmatic problems concerning this highly contentious legal concept. In doing so, he critically analyses some of the traditional prejudices towards so-called supergrasses, particularly the compatibility with the principle of the mandatory prosecution of offenses (Legalitätsprinzip) as well as with the principle of guilt (Schuldprinzip). The core of the work is a nationwide empirical study which examines the practical application of the accomplice evidence rule. It contains an online survey among judges, prosecutors, lawyers and policemen, an analysis of court decisions and (for the first time ever) a student survey about the present topic. It is the largest empirical study on accomplice witnesses in Germany so far.

Creoles are typologically distinct from non-creoles

2011 ◽  
Vol 26 (1) ◽  
pp. 5-42 ◽  
Author(s):  
Peter Bakker ◽  
Aymeric Daval-Markussen ◽  
Mikael Parkvall ◽  
Ingo Plag
Keyword(s):  
Empirical Study ◽  
Multiple Regression ◽  
Special Class ◽  
Phylogenetic Trees ◽  
Large Scale ◽  
Computational Tools ◽  
The Status ◽  
Creole Languages ◽  
First Time ◽  
Robust Evidence

In creolist circles, there has been a a long-standing debate whether creoles differ structurally from non-creole languages and thus would form a special class of languages with specific typological properties. This debate about the typological status of creole languages has severely suffered from a lack of systematic empirical study. This paper presents for the first time a number of large-scale empirical investigations of the status of creole languages as a typological class on the basis of different and well-balanced samples of creole and non-creole languages. Using statistical modeling (multiple regression) and recently developed computational tools of quantitative typology (phylogenetic trees and networks), this paper provides robust evidence that creoles indeed form a structurally distinguishable subgroup within the world’s languages. The findings thus seriously challenge approaches that hold that creole languages are structurally indistinguishable from non-creole languages.

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