Experiences from a Virtual Mapathon for collaborative Georeferencing of historical terrestrial Images in Alpine regions

2021 ◽  
Author(s):  
Sebastian Mikolka-Flöry ◽  
Tobias Heckmann ◽  
Michael Becht ◽  
Norbert Pfeifer
Keyword(s):  
Focal Length ◽  
Region Of Interest ◽  
Image Database ◽  
Quantitative Information ◽  
Small Areas ◽  
Alpine Regions ◽  
Historical Images ◽  
Spatial Coverage ◽  
Camera Location ◽  
Image Orientation

<p>Historical terrestrial images for identification, documentation, and especially the quantification of change in the alpine landscape are a largely unused source. Metric exploitation requires estimating the unknown camera parameters (camera location, angular attitude, and focal length) by photogrammetric resection. This is a challenging task, especially the identification of ground control points in mountainous terrain is time consuming and requires experience. Furthermore, due to the limited field of view of single images only small areas are captured. Hence, despite their possibility to provide quantitative information from more than one hundred years ago, integrating information from these historical images into subsequent analysis is often avoided.</p><p>Enabling their usage requires suitable software as well as users willing to engage in the challenge of image orientation. To facilitate this, a virtual Mapathon was organized, inviting participants to collaboratively orient historical images of the Val Martell (Italy) in the Ortler Alps. The participants from varying geoscience backgrounds (e.g. Botany, Climatology, Geomorphology, Glaciology, Hydrology) had little experience in photogrammetry prior to the Mapathon. Nevertheless, within one day nearly 100 images were oriented by 20 participants. The Mapathon was organized as a video conference using a web-based 3D image orientation software linked to an image database. Sessions with the whole group and in small teams alternated. Working in small teams stimulated internal discussions, promoting the understanding and success of each participant. Feedback received from the participants shows that the Mapathon helped overcoming the initial problem of getting started. Furthermore, the gained knowledge allows the participants to work with historical terrestrial images on their own in the future. </p><p>The set of oriented historical images created within the Mapathon further underlines the potential of historical terrestrial images. Due to  the availability of numerous oriented images, the limited fields of view of individual images can be combined, allowing the documentation of changes for larger areas. With the calculation of the viewshed for each image, the image database can not only be queried by metadata, but more importantly by location and spatial coverage. Especially the possibility to search for images capturing a certain region of interest will encourage scientists to include historical terrestrial images into their analysis.</p>

Improved Alignment Technique for Dish Concentrators

Solar Energy ◽  
2003 ◽  
Author(s):  
Charles E. Andraka ◽  
Richard B. Diver ◽  
K. Scott Rawlinson
Keyword(s):  
Focal Length ◽  
Electric Energy ◽  
Parabolic Systems ◽  
Companion Paper ◽  
Quantitative Information ◽  
Key Factors ◽  
Look Back ◽  
Parabolic Dish ◽  
The Individual

Parabolic dish concentrators have shown significant promise of generating competitive electric energy for grid and off-grid applications. The efficiency of a dish-electric system is strongly affected by the quality of the concentrator optics. Most parabolic systems consist of a number of facets mounted to a support structure in an approximate parabolic arrangement, where the individual facets have spherical or parabolic optical shapes. The individual facets must be accurately aligned because improper alignment can compromise performance or create hot spots that can reduce receiver life. A number of techniques have been used over the years to align concentrator facets. In the Advanced Dish Development System (ADDS) project, a color look-back alignment approach that accurately aligns facets (mirror panels) and in addition indicates quantitative information about the focal length was developed. Key factors influencing the alignment, some of which had very large effects on the quality of the alignment, were also identified. The influence of some of the key factors was characterized with a flux mapping system on the second-generation ADDS concentrator. Some of these factors also affect other alignment approaches. The approach was also successfully applied to two other concentrators with differing facet arrangements. Finally, we have extended the method to a 2-f approach that eliminates the need for a distant line-of-sight to the dish and permits alignment at near vertical dish attitudes. In this paper, we outline the color look-back alignment approach, discuss the key alignment factors and their effect on flux distribution, and discuss extensions to non-gore dishes. A companion paper discusses the 2-f color alignment approach in detail.

Determining Intrinsic Parameters and Pose of Cameras from Single View with Variable Focal Length

2014 ◽  
Vol 635-637 ◽  
pp. 1011-1017
Author(s):  
Gui Hua Liu ◽  
Hui Min Long
Keyword(s):  
Focal Length ◽  
Pinhole Camera ◽  
Projection Matrix ◽  
Camera Model ◽  
Intrinsic Parameter ◽  
Simulation Data ◽  
Single View ◽  
Estimated Parameters ◽  
Orientation Matrix ◽  
Camera Location

This study claims an algorithm of calibration which is executed on the basis of projection matrix. This algorithm directly estimates intrinsic parameter on the basis of rotation matrix’s unitary orthogonality combined with Cholesky decomposition from the obtained projection matrix. Then, false is excluded by rotation matrix’s determinant constraints, and ultimately, camera location and orientation matrix are obtained and estimated parameters are optimized with the minimum error of reprojection residual being cost function. This algorithm is taken under a pinhole camera model and can calibrate the camera from single view with variable focal length. Both simulation data and true image experiments have proved the feasibility and robustness of this algorithm.

Applying home-range and landscape-use data to design effective feral-cat control programs

2012 ◽  
Vol 39 (3) ◽  
pp. 258 ◽  
Author(s):  
Andrew J. Bengsen ◽  
John A. Butler ◽  
Pip Masters
Keyword(s):  
Home Range ◽  
Habitat Preferences ◽  
South Australia ◽  
Gps Tracking ◽  
Feral Cat ◽  
Feral Cats ◽  
Small Areas ◽  
Control Programs ◽  
Spatial Coverage ◽  
Landscape Use

Context Effective feral-cat (Felis silvestris catus) management requires a sound understanding of the ways cats use their environment. Key characteristics of landscape use by cats vary widely among different regions and different conditions. Aims The present study aimed to describe the most important characteristics of landscape use by feral cats on a large, human-populated island, and to use this information to guide the development of feral-cat management programs. Methods We used GPS tracking collars to record the movements of 13 feral cats at two sites on Kangaroo Island, South Australia, for between 20 and 106 days. We described home-range extents by using local convex hulls, and derived management suggestions from examination of home-range and movement data. Key results Median feral-cat home range was 5.11 km2, and this did not differ between sexes or sites. Cats at a fragmented pastoral site tended to favour woody vegetation over open paddocks, but habitat preferences were less clear at a bushland site. Cats that preferentially used treelines at the pastoral site were almost twice as likely to be recorded close to a tree-line junction as expected. Conclusions Control programs for feral cats on Kangaroo Island should deploy control devices at a density no less than 1.7 devices km–2. Spatial coverage should be as large as practicable or repeated frequently. Infrequent programs covering small areas can be expected only to provide short-term reductions in cat abundance. Implications The information gained from the present study will contribute to the development of strategic sustained management plans for feral cats on Kangaroo Island. The principles from which we inferred management guidelines are applicable to other regions and species.

scholarly journals Automated Target-Free Network Orienation and Camera Calibration

2014 ◽  
Vol II-5 ◽  
pp. 339-346 ◽  
Author(s):  
C. Stamatopoulos ◽  
C. S. Fraser
Keyword(s):  
Camera Calibration ◽  
Open Source Software ◽  
Focal Length ◽  
Relative Orientation ◽  
Aerial Imagery ◽  
Free Network ◽  
Close Range ◽  
Feature Based ◽  
Image Orientation ◽  
Matching Techniques

Automated close-range photogrammetric network orientation and camera calibration has traditionally been associated with the use of coded targets in the object space to allow for an initial relative orientation (RO) and subsequent spatial resection of the images. However, over the last decade, advances coming mainly from the computer vision (CV) community have allowed for fully automated orientation via feature-based matching techniques. There are a number of advantages in such methodologies for various types of applications, as well as for cases where the use of artificial targets might be not possible or preferable, for example when attempting calibration from low-level aerial imagery, as with UAVs, or when calibrating long-focal length lenses where small image scales call for inconveniently large coded targets. While there are now a number of CV-based algorithms for multi-image orientation within narrow-baseline networks, with accompanying open-source software, from a photogrammetric standpoint the results are typically disappointing as the metric integrity of the resulting models is generally poor, or even unknown. The objective addressed in this paper is target-free automatic multi-image orientation, maintaining metric integrity, within networks that incorporate wide-baseline imagery. The focus is on both the development of a methodology that overcomes the shortcomings that can be present in current CV algorithms, and on the photogrammetric priorities and requirements that exist in current processing pipelines. This paper also reports on the application of the proposed methodology to automated target-free camera self-calibration and discusses the process via practical examples.

scholarly journals Symptom-Based Identification of G-4 Chili Leaf Diseases Based on Rotation Invariant

2021 ◽  
Vol 8 ◽  
Author(s):  
Sufola Das Chagas Silva Araujo ◽  
V. S. Malemath ◽  
K. Meenakshi Sundaram
Keyword(s):  
Feature Learning ◽  
Region Of Interest ◽  
Physical Method ◽  
Image Database ◽  
Features Extraction ◽  
Plant Leaves ◽  
Rotation Invariant ◽  
Plant Leaf ◽  
Plant Image ◽  
Leaf Image

Instinctive detection of infections by carefully inspecting the signs on the plant leaves is an easier and economic way to diagnose different plant leaf diseases. This defines a way in which symptoms of diseased plants are detected utilizing the concept of feature learning (Sulistyo et al., 2020). The physical method of detecting and analyzing diseases takes a lot of time and has chances of making many errors (Sulistyo et al., 2020). So a method has been developed to identify the symptoms by just acquiring the chili plant leaf image. The methodology used involves image database, extracting the region of interest, training and testing images, symptoms/features extraction of the plant image using moments, building of the symptom vector feature dataset, and finding the correlation and similarity between different symptoms of the plant (Sulistyo et al., 2020). This will detect different diseases of the plant.

Algorithm for determining the orientation elements of an infrared image obtained from a drone using reference points

2020 ◽  
Vol 958 (4) ◽  
pp. 41-50
Author(s):  
S.M. Mokrova ◽  
R.P. Petrov ◽  
V.N. Milich
Keyword(s):  
Focal Length ◽  
Three Dimensional ◽  
Infrared Image ◽  
Image Plane ◽  
Reference Points ◽  
Spatial Coordinates ◽  
Aerial Vehicle ◽  
True Position ◽  
Image Orientation ◽  
Perspective Center

The article deals with the algorithm for determining the exterior and interior orientation elements of an infrared image obtained from an unmanned aerial vehicle using four reference points. The idea of the proposed algorithm is to determine the true position of the image by the defined three-dimensional spatial coordinates of the reference points in the image at the time of shooting. The image plane is built up on the defined points. The coordinates of the principal point of the image are calculated by making a perpendicular from the perspective center to the plane of the image. The focal length is equal to the length of this perpendicular. Euler angles characterizing the position of the camera at the time of shooting are calculated after determining the axes’ directions of the inclined image coordinate system. The proposed algorithm is effective even in the case when all the elements of the image orientation are unknown. Calculations of the image elements on model examples with different initial data show high accuracy. The possibility of obtaining the necessary accuracy for the orthotransformation procedure was confirmed on real images.

A New Accessory for Infrared Emission Spectroscopy Measurements

1986 ◽  
Vol 40 (3) ◽  
pp. 401-405 ◽  
Author(s):  
M. Handke ◽  
N. J. Harrick
Keyword(s):  
Background Radiation ◽  
Signal To Noise Ratio ◽  
Focal Length ◽  
Infrared Emission ◽  
Operating Conditions ◽  
Signal To Noise ◽  
Small Areas ◽  
Area Of Interest ◽  
Ellipsoidal Mirror ◽  
Noise Ratio

The principal problem in measurement of emission IR spectra is the low signal-to-noise ratio resulting from the large background radiation relative to sample emission. One method of increasing the signal is to collect the emitted radiation over a very large solid angle using an ellipsoidal mirror. In this method, placing the sample at the short focal length of the ellipsoid both increases the amount of radiation collected for an improved signal-to-noise ratio as well as facilitates sampling of small areas. For locating the area of interest, a microscope is mounted on the emission accessory. The results of testing this emission accessory under different operating conditions such as different samples, emission angles, temperatures, etc., are presented.

scholarly journals Methodology for deriving the telescope focus function and its uncertainty for a heterodyne pulsed Doppler lidar

2020 ◽  
Author(s):  
Pyry Pentikäinen ◽  
Ewan James O'Connor ◽  
Antti Juhani Manninen ◽  
Pablo Ortiz-Amezcua
Keyword(s):  
Signal To Noise Ratio ◽  
Focal Length ◽  
Quantitative Information ◽  
Absolute Difference ◽  
Beam Diameter ◽  
Doppler Lidar ◽  
Signal To Noise ◽  
Uncertainty Estimates ◽  
Noise Ratio ◽  
Two Parameters

Abstract. Doppler lidars provide two measured parameters, radial velocity and signal-to-noise ratio, from which winds and turbulent properties are routinely derived. Attenuated backscatter, which gives quantitative information on aerosols, clouds, and precipitation in the atmosphere, can be used in conjunction with the winds and turbulent properties to create a sophisticated classification of the state of the atmospheric boundary layer. Calculating attenuated backscatter from the signal-to-noise ratio requires accurate knowledge of the telescope focus function, which is usually unavailable. Inaccurate assumptions of the telescope focus function can significantly deform attenuated backscatter profiles, even if the instrument is focused at infinity. Here, we present a methodology for deriving the telescope focus function using a co-located ceilometer for Halo Photonics Streamline and XR pulsed heterodyne Doppler lidars. The method derives two parameters of the telescope focus function, the effective beam diameter and the effective focal length of the telescope. Additionally, the method provides uncertainty estimates for the retrieved attenuated backscatter profile arising from uncertainties in deriving the telescope function, together with standard measurement uncertainties from the signal-to-noise ratio. The method is best suited for locations where the absolute difference in aerosol extinction at the ceilometer and Doppler lidar wavelengths is small.

scholarly journals Big data and human biosensors – birthweight as a biomonitor for air pollution levels. A population based study using routine data.

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Chris Dibben ◽  
Tom Clemens
Keyword(s):  
Air Pollution ◽  
Low Cost ◽  
Routine Data ◽  
Local Area ◽  
Quantitative Information ◽  
Population Based ◽  
Small Areas ◽  
Pollution Levels ◽  
Routine Data Collection ◽  
The Individual

IntroductionIn the natural sciences biomonitors, (organisms, such as pine needles, shells, lichen, that can provide quantitative information on the quality of their past and present environments) have been developed for environmental measurement. In recent year’s physiologists have started to explore if human tissue could also be used. Objectives and ApproachThe costs of collecting and processing human tissues for biomonitoring, may be too prohibitive for its use in wide scale monitoring. In contrast if biomonitors could be identified within a routine data collection process that were part of standard medical recording a low cost, widely available large sample would be available to scientists. Pregnancy is known to be effected by air pollution, therefore we explore whether birthweight, recorded in maternity records, could be a biomonitor for air pollution. ResultsWe use maternity records (~1 million births) in Scotland between 2000 and 2015. We modelled, at the individual mother level birthweight, controlling mother’s age, estimated household income, local area crime rates and area level of multiple deprivation. We then aggregate and calculate the averaged of the residuals for this model for all mothers within an intermediate datazones (small areas of around 4000 residents). These mean deviations were then compared with pollution modelled figures produced by AEA for the Scottish government averaged over the same spatial units and time period as the maternity data. "We find a relatively strong correlations (between -0.37 and -0.39) between our ‘biomonitor estimates’ of air pollution derived from the maternity records and the entirely separated modelled air pollution data." Conclusion/ImplicationsAs far as we know this is the first study to demonstrate that it may be possible to use routine health data to derive ‘biomonitors’ information. Importantly if this method proves to be reliable it will be a relatively cheap method for collecting information that is actually personally monitoring.

Imaging With Spectroscopic Data

1987 ◽  
Vol 31 ◽  
pp. 69-75
Author(s):  
P. Engler ◽  
R. L. Barbour ◽  
J. H. Gibson ◽  
M. S. Hazle ◽  
D. G. Cameron ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Secondary Ion Mass Spectrometry ◽  
Region Of Interest ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Areas ◽  
Selective Area ◽  
Sample Extract ◽  
Ir And Raman Spectroscopies ◽  
Ir And Raman

Spectroscopic data from a var iety of analyt ical techniques such as x-ray diffraction (XRD), infrared (IR) and Raman spectroscopies, secondary ion mass spectrometry (SIMS) and energy dispersive X-ray analysis (EDX) can be obtained from small areas of samples (< 1 mm2) through the use of microscope sampling accessories. If provisions are made to scan or translate the sample, then a spectrum that is characteristic of each region of interest can be obtained. Alternatively, selective area detectors eliminate the requirement for scanning the sample. Extract ion of information about a specific energy band from each spectrum allows elucidat ion of the spatial distribution of the feature giving rise to that band. For example, the distribution of a compound could be imaged by extracting the intensity of an IR band or XRD peak due to that compound. Peak posit ion and peak width are other parameters that can be extracted as a function of posit ion. Similarly, elemental distributions could be obtained using SIMS and EDX.

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