Terrestrial Imaging Research Articles

The Ar-Hötöl surface rupture along the Khovd fault (Mongolian Altay)

ABSTRACT We present a 1:200,000 scale map of the Ar-Hötöl surface rupture along the Khovd fault (Mongolian Altay), presumed to be the expression of the 1761 CE Mw ∼ 7.8 Great Mongol earthquake. The detailed mapping combines airborne and terrestrial imaging and topographic techniques (Sentinel-2, Pleiades, TanDEM-X, UAV and TLS) to quantify right-lateral and vertical offsets ranging from ∼ 1 m to ∼ 4 km over a length of 238 km. The smaller offsets document the deformation associated with the last surface-rupturing earthquake that affects several Bronze to Iron Age burial mounds. Their analysis yields a robust segmentation model comprising 6 segments of 20 to 51 km in length, a maximum co-seismic slip value of 4.8 m ± 0.5 m located near the center of the rupture. Our observations precise the varying kinematics along strike, bring new evidence of repeated faulting and confirm a Mw of 7.8 ± 0.3.

Revealing microhabitat requirements of an endangered specialist lizard with LiDAR

A central principle of threatened species management is the requirement for detailed understanding of species habitat requirements. Difficult terrain or cryptic behaviour can, however, make the study of habitat or microhabitat requirements difficult, calling for innovative data collection techniques. We used high-resolution terrestrial LiDAR imaging to develop three-dimensional models of log piles, quantifying the structural characteristics linked with occupancy of an endangered cryptic reptile, the western spiny-tailed skink (Egernia stokesii badia). Inhabited log piles were generally taller with smaller entrance hollows and a wider main log, had more high-hanging branches, fewer low-hanging branches, more mid- and understorey cover, and lower maximum canopy height. Significant characteristics linked with occupancy were longer log piles, an average of three logs, less canopy cover, and the presence of overhanging vegetation, likely relating to colony segregation, thermoregulatory requirements, and foraging opportunities. In addition to optimising translocation site selection, understanding microhabitat specificity of E. s. badia will help inform a range of management objectives, such as targeted monitoring and invasive predator control. There are also diverse opportunities for the application of this technology to a wide variety of future ecological studies and wildlife management initiatives pertaining to a range of cryptic, understudied taxa.

The Spectral Mixture Residual: A Source of Low‐Variance Information to Enhance the Explainability and Accuracy of Surface Biology and Geology Retrievals

AbstractSpectrally mixed pixels are the rule, not the exception, in decameter terrestrial imaging. By definition, the reflectance spectrum of a mixed pixel is a function of more than one generative process. Physically based surface biology and geology retrievals must therefore isolate the component of interest from a myriad of unrelated processes, each occurring with unknown presence and abundance across the hundreds of square meters sampled by each pixel. Foliar traits, for example, must be isolated from canopy structure and substrate composition. In many cases, these unrelated processes can dominate overall variance of spatially integrated reflectance. We propose a new approach to isolate low‐variance spectral signatures in mixed pixels. The aggregate effects of (high‐variance) spatial mixing processes within each pixel are modeled by treating the observed reflectance as a linear mixture of a small set of generic endmember spectra. Spatial mixing effects are removed by computing the (low‐variance) difference between the modeled and observed spectra, named the Mixture Residual (MR). The MR, a residual reflectance spectrum that is presumed to carry the subtler and variable signals of interest, is then leveraged as a source of signal. We illustrate the approach using three independent collections of reflectance spectra: synthetic composites computed from field measurements, NEON AOP airborne image compilations, and DESIS satellite data. The MR is found to discriminate between land cover versus plant trait signals, and to accentuate subtle absorption features. Mean band‐to‐band correlations within the visible, NIR, and SWIR wavebands decrease from 0.97, 0.94, and 0.97 to 0.95, 0.04, and 0.31 (respectively). The number of dimensions required to explain 99% of image variance increases from 4 to 13. We focus on vegetation as an illustrative example, but note that the concept can be extended to other classes of spectra and used as an input to other algorithms.

Impact of heavy pruning on development and photosynthesis of Tilia cordata Mill. trees.

Tree pruning is carried out to reduce conflict with infrastructure, buildings, and any other human activity. However, heavy pruning may result in a diminished tree crown capacity for sugar production and exposure to fungal infection. This risk leads to a decrease in tree stability or vigour. In this work, we analysed the effect of heavy pruning of roadside trees on the photosynthetic performance process compared to neighbouring unpruned trees. Four years of tree crown growth was studied by terrestrial imaging. Tree vitality (Roloff’s classification) and risk (Visual Tree Assessment) were evaluated. Over-pruned trees showed intensified photosynthetic efficiency during the growing season following pruning. Particularly ET0/TR0 and PIABS tended to increase in pruned trees while higher Fv/Fm was noted only in late October, suggesting delayed leaf senescence. After four years, pruned trees rebuilt their crowns, however not in their entirety. Results obtained from biometric, vitality, and risk assessment showed high differentiation in pruned tree crown recovery. Our results revealed that despite the intensified efforts of trees to recover from wounding effects, severe pruning evokes dieback occurrence and a higher risk of failure in mature trees.

Digital Modelling and Accuracy Verification of a Complex Architectural Object Based on Photogrammetric Reconstruction

Data concerning heritage buildings are necessary for all kinds of building surveying and design. This paper presents a method for creating a precise model of a historical architectural and landscape object with complex geometry. Photogrammetric techniques were used, combining terrestrial imaging and photographs taken using UAVs. In large-scale objects, it is necessary to divide the reconstruction into smaller parts and adopt an iterative approach based on the gradual completion of missing fragments, especially those resulting from occlusions. The model developed via the reconstruction was compared with geometrically reliable data (LAS point clouds) available in the public domain. The degree of accuracy it achieved can be used in conservation, for example, in construction cost estimates. Despite extensive research on photogrammetric techniques and their applicability in reconstructing cultural heritage sites, the results obtained have not yet been compared by other researchers with LAS point clouds from the information system for land cover (ISOK).

Deep learning for anisoplanatic optical turbulence mitigation in long-range imaging

We present a deep learning approach for restoring images degraded by atmospheric optical turbulence. We consider the case of terrestrial imaging over long ranges with a wide field-of-view. This produces an anisoplanatic imaging scenario where turbulence warping and blurring vary spatially across the image. The proposed turbulence mitigation (TM) method assumes that a sequence of short-exposure images is acquired. A block matching (BM) registration algorithm is applied to the observed frames for dewarping, and the resulting images are averaged. A convolutional neural network (CNN) is then employed to perform spatially adaptive restoration. We refer to the proposed TM algorithm as the block matching and CNN (BM-CNN) method. Training the CNN is accomplished using simulated data from a fast turbulence simulation tool capable of producing a large amount of degraded imagery from declared truth images rapidly. Testing is done using independent data simulated with a different well-validated numerical wave-propagation simulator. Our proposed BM-CNN TM method is evaluated in a number of experiments using quantitative metrics. The quantitative analysis is made possible by virtue of having truth imagery from the simulations. A number of restored images are provided for subjective evaluation. We demonstrate that the BM-CNN TM method outperforms the benchmark methods in the scenarios tested.

Micro-electromechanical-system-tuned resonant filters spanning the 8-12 µm band.

The spectral band covering ∼8-12µm is atmospherically transparent and therefore important for terrestrial imaging, day/night situational awareness systems, and spectroscopic applications. There is a dearth of tunable filters spanning the band. Here, we propose and demonstrate a new, to the best of our knowledge, tunable-filter method engaging the fundamental physics of the guided-mode resonance (GMR) effect realized with a non-periodic lattice. The polarization-dependent filter is fashioned with a one-dimensional Ge grating on a ZnSe substrate and interrogated with a ∼1.5mm Gaussian beam to show clear transmittance nulls. To expand the tuning range, the device parameters are optimized for sequential operation in TM and TE polarization states. The theoretical model exhibits a tunable range exceeding 4 µm, thus covering the band fully. In the experiment, a prototype device exhibits a spectral range of 8.6-10.0 µm in TM and 9.9-11.7 µm in TE polarization or >3µm total. With additional efforts in fabrication, we expect to achieve the full range.

A new parallel DSP hardware compatible algorithm for noise reduction and contrast enhancement in video sequence using Zynq-7020

Various video processing applications such as liquid crystal display processing, high quality video photography, terrestrial video recording and medical imaging systems requires robust noise reduction and contrast enhancement technique which provides visually pleasing for real time implementation novel hardware architecture has been designed using look-up-table (LUT) acceleration approach which helps achieve high speed processing. Until now, a lot of researchers have worked on noise removal and contrast enhancement of digital videos, but the developed algorithms works with only some verity of noises and failed to produce desirable results for various types of distortions and real time implementation is still remaining a challenge. Hence, appropriate filter needs to be designed which address both kinds of errors. In this paper, adaptive trilateral filter has been designed for noise reduction the results are measured using qualitative and quantitative analysis which has aided in better utilisation of hardware for real time implementation. The experimental results show that the proposed algorithm provides a frame rate of 40 fps on an average and has a resolution of 720 × 576. The proposed algorithm was implemented on ZedBoard Znyq-7020 development kit by Xilinx.

Spectral Band Optical Analysis for Shape and Material of Terrestrial Imaging by Using Remote Sensing Technique

Photogrammetric grid is the generation of processing system (which is one of the remote sensing techniques) with efficiency developed based on imaging and computer cluster parallel processing; the new application of photogrammetric technique has been applied on the Castel-Gate of Erbil city. It is a way of analyzing the objects especially for a traditional one "the castle in the ancient city of Erbil". This paper got the analysis of Erbil Castel-Gate structure using visible & IR spectral band analysis for transmission and absorption energy (El ) based on civil study, as well as the analyzing of chemical & physical test. On other hand the Satellite image of castle has been analyzed by using photogrammetric & GIS techniques. The result calculated the reflected energy values.

Spectral Band Optical Analysis for Shape and Material of Terrestrial Imaging by Using Remote Sensing Technique

Photogrammetric grid is the generation of processing system (which is one of the remote sensing techniques) with efficiency developed based on imaging and computer cluster parallel processing; the new application of photogrammetric technique has been applied on the Castel-Gate of Erbil city. It is a way of analyzing the objects especially for a traditional one "the castle in the ancient city of Erbil". This paper got the analysis of Erbil Castel-Gate structure using visible & IR spectral band analysis for transmission and absorption energy (El ) based on civil study, as well as the analyzing of chemical & physical test. On other hand the Satellite image of castle has been analyzed by using photogrammetric & GIS techniques. The result calculated the reflected energy values.

The survey of the Basilica di Collemaggio in L’Aquila with a system of terrestrial imaging and most proven techniques

ABSTRACTThe proposed job concerns the evaluation of a series of surveys carried out in the context of a campaign of studies begun in 2015 with the objective of comparing the accuracies obtainable with the systems of terrestrial imaging, compared to unmanned aerial vehicle imaging and laser scanner survey. In particular, the authors want to test the applicability of a system of imaging rover (IR), an innovative terrestrial imaging system, that consists of a multi-camera with integrated global positioning system (GPS)/global navigation satellite system (GNSS) receiver, that is very recently released technique, and only a few literature references exist on the specific subject. In detail, the IR consists of a total of 12 calibrated cameras – seven “panorama” and five downward-looking – providing complete site documentation that can potentially be used to make photogrammetric measurements. The data acquired in this experimentation were then elaborated with various software packages in order to obtain point clouds and a three-dimensional model in different cases, and a comparison of the various results obtained was carried out. Following, the case study of the Basilica di Santa Maria di Collemaggio in L’Aquila is reported; Collemaggio is an UNESCO world heritage site; it was damaged during the seismic event of 2009, and its restoration is still in progress.

Investigating the Surface and Subsurface in Karstic Regions – Terrestrial Laser Scanning versus Low-Altitude Airborne Imaging and the Combination with Geophysical Prospecting

Combining measurements of the surface and subsurface is a promising approach to understand the origin and current changes of karstic forms since subterraneous processes are often the initial driving force. A karst depression in south-west Germany was investigated in a comprehensive campaign with remote sensing and geophysical prospecting. This contribution has two objectives: firstly, comparing terrestrial laser scanning (TLS) and low-altitude airborne imaging from an unmanned aerial vehicle (UAV) regarding their performance in capturing the surface. Secondly, establishing a suitable way of combining this 3D surface data with data from the subsurface, derived by geophysical prospecting. Both remote sensing approaches performed satisfying and the established digital elevation models (DEMs) differ only slightly. These minor discrepancies result essentially from the different viewing geometries and post-processing concepts, for example whether the vegetation was removed or not. Validation analyses against high-accurate DGPS-derived point data sets revealed slightly better results for the DEMTLS with a mean absolute difference of 0.03 m to 0.05 m and a standard deviation of 0.03 m to 0.07 m (DEMUAV: mean absolute difference: 0.11 m to 0.13 m; standard deviation: 0.09 m to 0.11 m). The 3D surface data and 2D image of the vertical cross section through the subsurface along a geophysical profile were combined in block diagrams. The data sets fit very well and give a first impression of the connection between surface and subsurface structures. Since capturing the subsurface with this method is limited to 2D and the data acquisition is quite time consuming, further investigations are necessary for reliable statements about subterraneous structures, how these may induce surface changes, and the origin of this karst depression. Moreover, geophysical prospecting can only produce a suspected image of the subsurface since the apparent resistivity is measured. Thus, further measurements, such as borehole drillings or ground-penetrating radar are necessary for a closer analysis of the subsurface. In summary, satisfying results were achieved, which however pave the way for further studies.

Volumetric Water Content Measurements as Obtained from Remote Sensing and In Situ Instrumentation

A single-polarization, vertical wave propagation transmitted-vertical wave propagation received (VV), terrestrial imaging radar and time domain reflectometry (TDR) equipment were used to monitor the fluctuations of water content within two thin (15.24 centimeters) compacted clay test sections (each 30.48-m long, by 15.34-m wide). Radar imagery was obtained in 2013 on March 22, June 26, July 7 and July 10 using a Gamma Remote Sensing Portable Radar Interferometer version II (GAMMA Remote Sensing and Consulting AG, Bern, Switzerland). In situ observations were acquired hourly using TDR probes. The background, methodology, and comparison of the results of the remote sensing and in situ measurements are presented. Specifically, two remote sensing data reduction algorithms were considered. The water content results obtained from these algorithms were compared with the water content values derived from correlations with the dielectric permittivity values measured by the TDR probes. Key findings include: 1) there were differences between the values obtained from the data reduction methods, 2) there were differences between the values obtained from the remote sensing methods and the values obtained from the in situ method, and 3) the identification of additional avenues of research. The remotely sensed measurements were, on average, higher than the in situ measurements (the average volumetric water content values were 0.2 and 0.5 depending on the method, as obtained via the remotely sensed methods; the average volumetric water content value in the compacted native soil test sections was 0.22, as obtained via the in situ method).

A REVIEW OF HYPERSPECTRAL IMAGING IN CLOSE RANGE APPLICATIONS

Abstract. Hyperspectral imaging is an established method for material mapping, which has been conventionally applied from airborne and spaceborne platforms for a range of applications, including mineral and vegetation mapping, change detection and environmental studies. The main advantage of lightweight hyperspectral imagers lies in the flexibility to deploy them from various platforms (terrestrial imaging and from unmanned aerial vehicles; UAVs), as well as the high spectral resolution to cover an expanding wavelength range. In addition, spatial resolution allows object sampling distances from micrometres to tens of centimetres – complementary to conventional nadir-looking systems. When this new type of imaging device was initially released, few instruments were available and the applicability and potential of the method was restricted. Today, a wider range of instruments, with a range of specifications, is available, with significant improvements over the first generation of technology. In this contribution, the state-of-the-art of hyperspectral imaging will be reviewed from a close range measurement perspective, highlighting how the method supplements geometric modelling techniques. An overview of the processing workflow, adjusted to the more complex close range imaging scenario will be given. This includes the integration with 3D laser scanning and photogrammetric models to provide a geometric framework and real world coordinate system for the hyperspectral imagery.

A REVIEW OF HYPERSPECTRAL IMAGING IN CLOSE RANGE APPLICATIONS

Hyperspectral imaging is an established method for material mapping, which has been conventionally applied from airborne and spaceborne platforms for a range of applications, including mineral and vegetation mapping, change detection and environmental studies. The main advantage of lightweight hyperspectral imagers lies in the flexibility to deploy them from various platforms (terrestrial imaging and from unmanned aerial vehicles; UAVs), as well as the high spectral resolution to cover an expanding wavelength range. In addition, spatial resolution allows object sampling distances from micrometres to tens of centimetres – complementary to conventional nadir-looking systems. When this new type of imaging device was initially released, few instruments were available and the applicability and potential of the method was restricted. Today, a wider range of instruments, with a range of specifications, is available, with significant improvements over the first generation of technology. In this contribution, the state-of-the-art of hyperspectral imaging will be reviewed from a close range measurement perspective, highlighting how the method supplements geometric modelling techniques. An overview of the processing workflow, adjusted to the more complex close range imaging scenario will be given. This includes the integration with 3D laser scanning and photogrammetric models to provide a geometric framework and real world coordinate system for the hyperspectral imagery.

On the formal analysis of Gaussian optical systems in HOL

Abstract Optics technology is being increasingly used in mainstream industrial and research domains such as terrestrial telescopes, biomedical imaging and optical communication. One of the most widely used modeling approaches for such systems is Gaussian optics, which describes light as a beam. In this paper, we propose to use higher-order-logic theorem proving for the analysis of Gaussian optical systems. In particular, we present the formalization of Gaussian beams and verify the corresponding properties such as beam transformation, beam waist radius and location. Consequently, we build formal reasoning support for the analysis of quasi-optical systems. In order to demonstrate the effectiveness of our approach, we present a case study about the receiver module of a real-world Atacama Pathfinder Experiment (APEX) telescope.

Technical Note: Semi-automated effective width extraction from time-lapse RGB imagery of a remote, braided Greenlandic river

Abstract. River systems in remote environments are often challenging to monitor and understand where traditional gauging apparatus are difficult to install or where safety concerns prohibit field measurements. In such cases, remote sensing, especially terrestrial time-lapse imaging platforms, offer a means to better understand these fluvial systems. One such environment is found at the proglacial Isortoq River in southwestern Greenland, a river with a constantly shifting floodplain and remote Arctic location that make gauging and in situ measurements all but impossible. In order to derive relevant hydraulic parameters for this river, two true color (RGB) cameras were installed in July 2011, and these cameras collected over 10 000 half hourly time-lapse images of the river by September of 2012. Existing approaches for extracting hydraulic parameters from RGB imagery require manual or supervised classification of images into water and non-water areas, a task that was impractical for the volume of data in this study. As such, automated image filters were developed that removed images with environmental obstacles (e.g., shadows, sun glint, snow) from the processing stream. Further image filtering was accomplished via a novel automated histogram similarity filtering process. This similarity filtering allowed successful (mean accuracy 79.6 %) supervised classification of filtered images from training data collected from just 10 % of those images. Effective width, a hydraulic parameter highly correlated with discharge in braided rivers, was extracted from these classified images, producing a hydrograph proxy for the Isortoq River between 2011 and 2012. This hydrograph proxy shows agreement with historic flooding observed in other parts of Greenland in July 2012 and offers promise that the imaging platform and processing methodology presented here will be useful for future monitoring studies of remote rivers.

Towards a Risk Management and Conservation Plan for the Djin Blocks at the World Heritage Site of Petra, Jordan: The Case of Djin Block No. 9

Cultural heritage is subjected to many pressures and risks. Over the past few years, the use of digital technologies has significantly changed the approaches to cultural heritage documentation for the purpose of condition assessment and conservation. The integration of novel approaches and techniques has permitted a detailed examination and assessment of damage, deterioration due to weathering and erosion, and their mechanisms. This study seeks to contribute to the preservation and conservation of the significant heritage of the so-called Djin Blocks at the World Heritage Site of Petra in Jordan. While these three dimensional cuboid rock-cut monuments have been subject to extensive conservation studies, this is the first time they have been subjected to 3D recording and multispectral photography, with the aim of recording damage caused by the ravages of time.This study presents the results of the documentation of the case study Djin Block No. 9. A variety of systematic documentation techniques were used, including 3D recording with terrestrial laser scanning (TLS), close-range photogrammetry, multispectral imaging, and thermography records. In addition, pathological studies of the erosion from various causes and an analysis of the effect of weathering on Djin Block No. 9 are performed. Based on this data, the paper presents recommendations for developing risk management and conservation planning of Djin Block No. 9.

Hydrogeology of the Skadar Lake basin (Southeast Dinarides) with an assessment of considerable subterranean inflow

The Skadar Lake basin is located in the south-eastern part of the classical Dinaric karst region (northern Mediterranean). This region is well known for its highly developed karst and the presence of all types of karstic features. In addition to the high degree of karstification, the advantage of Skadar Lake’s catchment area in terms of water resources is also reflected in the following factors: a large amount of precipitation, scarcity of soil and vegetation cover, favourable geological and geomorphological conditions for karst aquifer discharge, the isolation of the Skadar basin from the influence of the Adriatic Sea and an availability of water for simple abstraction. For the purposes of a more complete determination of the water balance of Skadar Lake, among other undertakings, it has been necessary to determine the groundwater inflow to the lake through numerous sublacustrine springs (vruljas). By using thermal infrared satellite and terrestrial imaging, the locations of the largest sublacustrine springs have been detected and their yield assessed by means of water balance calculation after the application of the KARSTLOP method. The mean annual groundwater inflow to the lake, from the south-western edge only, is 9.86 m3/s. The total outflow of water from the lake through the Bojana River is around 304 m3/s. The coincidence of several important natural factors leads to the large average specific yield (surface and subsurface) in the Skadar Lake catchment area (54 l/s/km2), which makes this region one of the richest areas of freshwater in the world.

Mapping of iron and steelwork by-products using close range hyperspectral imaging: A case study in Thuringia, Germany

This paper presents the first use of close range terrestrial hyperspectral imaging to explore by-products from the iron and steel industry at a dump site cross section, using established mapping approaches in geological remote sensing. Laboratory reflectance measurements, X-Ray diffraction and chemical analysis provided a benchmark for the imaging results. In addition, terrestrial laser scanning was applied to create a high resolution 3D model of the studied section, for hyperspectral image and classification integration. Results demonstrate the applicability of spectral methods for remote discrimination and mapping of materials from iron and steel production which are of potential economic interest. This will aid the appraisal of resource distribution for urban mining and material recycling.