scholarly journals Assessing a 35mm Fixed-Lens Sony Alpha-5100 Intrinsic Parameters Prior to, During, and Post UAV Flight Mission

2019 ◽  
Author(s):  
Martinus E Tjahjadi ◽  
Silvester S Sai ◽  
Fourry Handoko
Keyword(s):  
Aerial Photography ◽  
Focal Length ◽  
Digital Camera ◽  
Optical Quality ◽  
Bundle Adjustment ◽  
Principal Point ◽  
Intrinsic Parameters ◽  
Stability Performance ◽  
Focal Length Lens ◽  
Cmos Sensor

A fixed focal length lens (FFL) camera with on-adjustable focal length is common companions for conducting aerial photography using unmanned aerial vehicles (UAVs) due to its superiority on optical quality and wider maximum aperture, lighter weight and smaller sizes. A wide-angle 35mm FFL Sony a5100 camera had been used extensively in our recent aerial photography campaign using UAV. Since this off-the-self digital camera is categorized into a non-metric one, a stability performance issue in terms of intrinsic parameters raises a considerably attention, particularly on variations of the lens principal distance and principal point’s position relative to the camera’s CCD/CMOS sensor caused by the engine and other vibrations during flight data acquisitions. A series of calibration bundle adjustment was conducted to determine variations in the principal distances and principal point coordinates before commencing, during, and after accomplishment of the flight missions. This paper demonstrates the computation of the parameters and presents the resulting parameters for three different epochs. It reveals that there are distinct discrepancies of the principal distances and principal point coordinates prior to, during, and after the mission, that peaked around 1.2mm for the principal distance, as well as around 0.4mm and 1.3mm along the x-axis and the y-axis of the principal point coordinates respectively. In contrast, the lens distortions parameters show practically no perturbations in terms of radial, decentering, and affinity distortion terms during the experiments.

scholarly journals INVESTIGATION INTO THE BEHAVIOUR AND MODELLING OF CHROMATIC ABERRATIONS IN NON-METRIC DIGITAL CAMERAS

2019 ◽  
Vol XLII-2/W18 ◽  
pp. 99-106 ◽  
Author(s):  
D. D. Lichti ◽  
D. Jarron ◽  
M. Shahbazi ◽  
P. Helmholz ◽  
R. Radovanovic
Keyword(s):  
Digital Camera ◽  
Chromatic Aberration ◽  
Bundle Adjustment ◽  
Lens Distortion ◽  
Digital Cameras ◽  
Principal Point ◽  
Common Object ◽  
Chromatic Aberrations ◽  
The Impact ◽  
Orientation Parameters

Abstract. Chromatic aberration in colour digital camera imagery can affect the accuracy of photogrammetric reconstruction. Both longitudinal and transverse chromatic aberrations can be effectively modelled by making separate measurements in each of the blue, green and red colour bands and performing a specialized self-calibrating bundle adjustment. This paper presents the results of an investigation with two aims. The first aim is to quantify the presence of chromatic aberration in two sets of cameras: the six individual cameras comprising a Ladybug5 system, calibrated simultaneously in air; and four GoPro Hero 5 cameras calibrated independently under water. The second aim is to investigate the impacts of imposing different constraints in the self-calibration adjustment. To this end, four different adjustment cases were performed for all ten cameras: independent adjustment of the observations from each colour band; combined adjustment of all colour bands’ observations with common object points; combined adjustment of all colour bands with common object points and common exterior orientation parameters for each colour band triplet; and combined adjustment with common object points and certain common interior orientation parameters. The results show that the Ladybug5 cameras exhibit a small (1-2 pixel) amount of transverse chromatic aberration but no longitudinal chromatic aberration. The GoPro Hero 5 cameras exhibit significant (25 pixel) transverse chromatic aberration as well as longitudinal chromatic aberration. The principal distance was essentially independent of the adjustment case for the Ladybug5, but it was not for the GoPro Hero 5. The principal point position and precision were both affected considerably by adjustment case. Radial lens distortion was invariant to the adjustment case. The impact of adjustment case on decentring distortion was minimal in both cases.

scholarly journals Orthoimages of the outer walls and towers of the château de Chambord

2015 ◽  
Vol II-5/W3 ◽  
pp. 243-250
Author(s):  
A. Pinte ◽  
R. Héno ◽  
M. Pierrot-Deseilligny ◽  
X. Brunetaud ◽  
S Janvier-Badosa ◽  
...  
Keyword(s):  
Focal Length ◽  
Meteorological Data ◽  
Ground Level ◽  
Bundle Adjustment ◽  
Data Sets ◽  
French Renaissance ◽  
Gis Applications ◽  
Focal Length Lens ◽  
World Heritage List ◽  
Visualization Of Data

The <i>château de Chambord</i> is one of the most famous castles in the world as it is an emblem of French Renaissance architecture. It was built at the beginning of the 16<sup>th</sup> century and has been part of the UNESCO World Heritage list since 1981. The monitoring of such a monument involves the organization and visualization of data sets such as archive documents, survey data, scientific documentation, restoration reports, meteorological data, etc. This process requires the realization of a support for documentation which may be an orthoimage. A photogrammetric survey was recently performed, in the framework of the traditional fieldwork of the students in the PPMD master's degree (Specialized Master’s in Positionning, Photogrammetry and Deformation Measurement) at the French National School of Geographic Sciences (ENSG). High resolution images were taken from the ground level, using two off-the-shelf reflex cameras, equipped with a 35 mm, a 100 mm and a 200 mm focal length lens according to the needs. The MicMac software was used for the bundle adjustment, the georeferencing and the dense correlation procedures, including orthoimage calculation. Added to plane-based orthoimages, cylinder-based orthoimages were generated for the 2D representation of the outer walls of the château de Chambord including façades and towers. Fitting the 2D projection to the mean characteristics of the geometry has a promising documentation potential for GIS applications in heritage studies.

scholarly journals Performance evaluation of thermographic cameras for photogrammetric documentation of historical buildings

2013 ◽  
Vol 19 (4) ◽  
pp. 711-728 ◽  
Author(s):  
Naci Yastikli ◽  
Esra Guler
Keyword(s):  
Performance Evaluation ◽  
Focal Length ◽  
Digital Camera ◽  
Infrared Region ◽  
Historical Buildings ◽  
Principal Point ◽  
Geometric Calibration ◽  
Thermal Cameras ◽  
Thermographic Camera ◽  
And Performance

Thermographic cameras record temperatures emitted by objects in the infrared region. These thermal images can be used for texture analysis and deformation caused by moisture and isolation problems. For accurate geometric survey of the deformations, the geometric calibration and performance evaluation of the thermographic camera should be conducted properly. In this study, an approach is proposed for the geometric calibration of the thermal cameras for the geometric survey of deformation caused by moisture. A 3D test object was designed and used for the geometric calibration and performance evaluation. The geometric calibration parameters, including focal length, position of principal point, and radial and tangential distortions, were determined for both the thermographic and the digital camera. The digital image rectification performance of the thermographic camera was tested for photogrammetric documentation of deformation caused by moisture. The obtained results from the thermographic camera were compared with the results from digital camera based on the experimental investigation performed on a study area.

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.

scholarly journals INVESTIGATIONS ON THE BUNDLE ADJUSTMENT RESULTS FROM SFM-BASED SOFTWARE FOR MAPPING PURPOSES

2018 ◽  
Vol XLII-2 ◽  
pp. 623-628
Author(s):  
Y. A. Lumban-Gaol ◽  
A. Murtiyoso ◽  
B. H. Nugroho
Keyword(s):  
Aerial Photography ◽  
Large Scale ◽  
Bundle Adjustment ◽  
Aerial Images ◽  
Topographic Maps ◽  
Main Method ◽  
Aerial Photogrammetry ◽  
Lower Accuracy ◽  
Spatial Management ◽  
Erdas Imagine

Since its first inception, aerial photography has been used for topographic mapping. Large-scale aerial photography contributed to the creation of many of the topographic maps around the world. In Indonesia, a 2013 government directive on spatial management has re-stressed the need for topographic maps, with aerial photogrammetry providing the main method of acquisition. However, the large need to generate such maps is often limited by budgetary reasons. Today, SfM (Structure-from-Motion) offers quicker and less expensive solutions to this problem. However, considering the required precision for topographic missions, these solutions need to be assessed to see if they provide enough level of accuracy. In this paper, a popular SfM-based software Agisoft PhotoScan is used to perform bundle adjustment on a set of large-scale aerial images. The aim of the paper is to compare its bundle adjustment results with those generated by more classical photogrammetric software, namely Trimble Inpho and ERDAS IMAGINE. Furthermore, in order to provide more bundle adjustment statistics to be compared, the Damped Bundle Adjustment Toolbox (DBAT) was also used to reprocess the PhotoScan project. Results show that PhotoScan results are less stable than those generated by the two photogrammetric software programmes. This translates to lower accuracy, which may impact the final photogrammetric product.

A Robust Feature Points Matching Algorithm in 3D Optical Measuring System

2011 ◽  
Vol 383-390 ◽  
pp. 5193-5199 ◽  
Author(s):  
Jian Ying Yuan ◽  
Xian Yong Liu ◽  
Zhi Qiang Qiu
Keyword(s):  
3D Reconstruction ◽  
Digital Camera ◽  
Image Data ◽  
Epipolar Geometry ◽  
Bundle Adjustment ◽  
Measuring System ◽  
Feature Points ◽  
3 Dimensional ◽  
Feature Points Matching ◽  
Optical Measuring

In optical measuring system with a handheld digital camera, image points matching is very important for 3-dimensional(3D) reconstruction. The traditional matching algorithms are usually based on epipolar geometry or multi-base lines. Mistaken matching points can not be eliminated by epipolar geometry and many matching points will be lost by multi-base lines. In this paper, a robust algorithm is presented to eliminate mistaken matching feature points in the process of 3D reconstruction from multiple images. The algorithm include three steps: (1) pre-matching the feature points using constraints of epipolar geometry and image topological structure firstly; (2) eliminating the mistaken matching points by the principle of triangulation in multi-images; (3) refining camera external parameters by bundle adjustment. After the external parameters of every image refined, repeat step (1) to step (3) until all the feature points been matched. Comparative experiments with real image data have shown that mistaken matching feature points can be effectively eliminated, and nearly no matching points have been lost, which have a better performance than traditonal matching algorithms do.

A Stratified Optimization Method for Camera Self-Calibration

2012 ◽  
Vol 580 ◽  
pp. 248-252
Author(s):  
Qian Sun ◽  
Dong Xu
Keyword(s):  
Aspect Ratio ◽  
Accurate Result ◽  
Focal Length ◽  
Optimization Method ◽  
Singular Value ◽  
Optimization Approach ◽  
Point Location ◽  
Principal Point ◽  
Self Calibration ◽  
Value Decomposition

We present an efficient stratified optimization approach for self-calibration of a camera in the case that its focal length and the principal point location are unknown. Generally we can assume that the two views are of the same focal length, and the pixels are nearly perfectly rectangular, also it is possible to know the aspect ratio rather accurately. In our approach, we use singular value decomposition to solve a modified Kruppa Equation to derive the focal length with the supposition that the principal point is at the center of the image, and perform an exhaustive search for the principal point near the center of the image to minimize a cost function. We can get a much accurate result with the optimized principal point location.

Accuracy Assessment of Commercial Self-Calibrating Bundle Adjustment Routines Applied to Archival Aerial Photography

2012 ◽  
Vol 28 (141) ◽  
pp. 96-114 ◽  
Author(s):  
Manuel A. Aguilar ◽  
Fernando J. Aguilar ◽  
Ismael Fernández ◽  
Jon P. Mills
Keyword(s):  
Aerial Photography ◽  
Accuracy Assessment ◽  
Bundle Adjustment
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