The InflateSAR Campaign: Testing SAR Vessel Detection Systems for Refugee Rubber Inflatables

Lanz, Peter; Marino, Armando; Brinkhoff, Thomas; Köster, Frank; Möller, Matthias

doi:10.3390/rs13081487

Cited by 5 publications

(9 citation statements)

References 65 publications

(86 reference statements)

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“…[32] used wet sand for Ultra Wide Band (UWB) radar. In our experiment, we expect a stronger intensity signature compared to an empty boat (see [24]).…”

Section: Data Campaign and Data Collectionmentioning

confidence: 59%

“…Those data enabled us to examine the radar pattern of our special maritime vessel under different combinations of scene parameters (e.g., the incidence angle and resolution) and sensor parameters (e.g., the boat orientation) and to evaluate them for their impact on the detectability of the inflatable. We tested and compared a variety of existing automatic vessel detectors [24]. Our results are, we think, noteworthy and legitimate and offer significant insights regarding the behaviour of the inflatable when hit by microwaves and the interactions with the surrounding water surface.…”

Section: Introductionmentioning

confidence: 81%

“…Since we applied it to all available combinations of dual-pol data, including HH VV, we refer to it here as PolRatio1 when used with cross-pol data and PolRatio3 when used with co-pol data. The same is true for its surface and double-bounce scattering detecting variant SiDPolRAD [24], which we rename as PolRatio2 when used with cross-pol data and PolRatio4 when used with co-pol data. For VH VV and HV HH, the two detectors are defined as:…”

Section: Detector Comparison and Detector Fusionmentioning

confidence: 97%

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The InflateSAR Campaign: Developing Refugee Vessel Detection Capabilities with Polarimetric SAR

et al. 2023

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In the efforts to mitigate the ongoing humanitarian crisis at the European sea borders, this work builds detection capabilities to help find refugee boats in distress. For this paper, we collected dual-pol and quad-pol synthetic aperture radar (SAR) data over a 12 m rubber inflatable in a test-bed lake near Berlin, Germany. To consider a real scenario, we prepared the vessel so that its backscattering emulated that of a vessel fully occupied with people. Further, we collected SAR imagery over the ocean with different sea states, categorized by incidence angle and by polarization. These were used to emulate the conditions for a vessel located in ocean waters. This setup enabled us to test nine well-known vessel-detection systems (VDS), to explore the capabilities of new detection algorithms and to benchmark different combinations of detectors (detector fusion) with respect to different sensor and scene parameters (e.g., the polarization, wind speed, wind direction and boat orientation). This analysis culminated in designing a system that is specifically tailored to accommodate different situations and sea states.

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“…[32] used wet sand for Ultra Wide Band (UWB) radar. In our experiment, we expect a stronger intensity signature compared to an empty boat (see [24]).…”

Section: Data Campaign and Data Collectionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 81%

Section: Detector Comparison and Detector Fusionmentioning

confidence: 97%

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The InflateSAR Campaign: Developing Refugee Vessel Detection Capabilities with Polarimetric SAR

et al. 2023

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“…However, radar images suffer from large intrinsic noise (speckle), in addition to the azimuth displacements ("train-off-the-track effect"), which are caused by the Doppler effect, and the azimuth ambiguity patterns ("ghost"), which are weaker, repetitive artefacts appearing in coastal areas, caused by the presence of brighter objects on the mainland (e.g., [263]). False positive detections can occur in non-homogeneous areas of the images due to changes in ocean backscattering or to oceanographic phenomena, e.g., atmospheric fronts, internal waves, current boundaries, breaking waves, outlying rocks, shoal sea currents, and coastal effects, while high wind and rough sea states can hamper the correct identification of small vessels [255,264].…”

Section: Application 6: Earth Observation For Vessel Detectionmentioning

confidence: 99%

A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation

et al. 2022

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In this paper, we present several study cases focused on marine, oceanographic, and atmospheric environments, which would greatly benefit from the use of a deployable system for small satellite observations. As opposed to the large standard ones, small satellites have become an effective and affordable alternative access to space, owing to their lower costs, innovative design and technology, and higher revisiting times, when launched in a constellation configuration. One of the biggest challenges is created by the small satellite instrumentation working in the visible (VIS), infrared (IR), and microwave (MW) spectral ranges, for which the resolution of the acquired data depends on the physical dimension of the telescope and the antenna collecting the signal. In this respect, a deployable payload, fitting the limited size and mass imposed by the small satellite architecture, once unfolded in space, can reach performances similar to those of larger satellites. In this study, we show how ecology and Earth Observations can benefit from data acquired by small satellites, and how they can be further improved thanks to deployable payloads. We focus on DORA—Deployable Optics for Remote sensing Applications—in the VIS to TIR spectral range, and on a planned application in the MW spectral range, and we carry out a radiometric analysis to verify its performances for Earth Observation studies.

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“…Using an active sensor system, SAR images can be taken by day or night and regardless of weather conditions (Fernandez Arguedas et al, 2016). This opens up the possibility of detecting vessel activity that ranges from undeclared and illegal to recreational (Galdelli et al, 2020;Lanz et al, 2021). In contrast to fishing activities that are monitored, at least partly, through catch reports and AIS data, marine leisure activities are still challenging to assess, even more during the Covid-19 crisis while their impact on marine ecosystems and fish stocks is far from being negligible, targeting a large proportion of vulnerable species (Lewin et al, 2019;Hyder et al, 2020;Lloret et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

SAR Satellite Imagery Reveals the Impact of the Covid-19 Crisis on Ship Frequentation in the French Mediterranean Waters

et al. 2022

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The Covid-19 pandemic is the latest example in a growing number of health, social, economic, and environmental crises humanity is facing. The multiple consequences of this pandemic crisis required strong responses from governments, including strict lockdowns. Yet, the impact of lockdowns on coastal ecosystems and maritime activities is still challenging to quantify over large spatial scales in comparison to the pre-Covid period. In this study, we used an object detection algorithm on Synthetic Aperture Radar (SAR) images acquired by the two Sentinel-1 satellites to assess the impact of the Covid-19 crisis on the presence of boats before, during and after lockdown periods in the French Mediterranean Exclusive Economic Zone. During the French most severe lockdown period (March – May 2020), we observed that ship frequentation remained at the same level from March to July 2020, instead of rising towards the summer peak like in previous years. Then, ship frequentation increased rapidly to a normal level in August 2020 when restrictions were lifted. By comparing morning and evening (7:00 am and 7:00 pm) ship frequentation during this period to pre-Covid years, we observed contrasting patterns. On the one hand, morning detections were particularly high, while on the other hand evening detections were significantly lower and less concentrated in coastal touristic waters than in previous years. Overall, we found a 9% decrease in ship frequentation between the year 2020 and the 2017-2019 period, with a maximum of 43% drop in June 2020 due to the lockdown. So, the Covid -19 crisis induced only a very short-term reduction in maritime activities but did not markedly reduce the annual ship frequentation in the French Mediterranean waters. The satellite imagery approach is an alternative method that improves our understanding of the pandemic impacts at an unprecedented spatiotemporal scale and resolution.

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The InflateSAR Campaign: Testing SAR Vessel Detection Systems for Refugee Rubber Inflatables

Cited by 5 publications

References 65 publications

The InflateSAR Campaign: Developing Refugee Vessel Detection Capabilities with Polarimetric SAR

The InflateSAR Campaign: Developing Refugee Vessel Detection Capabilities with Polarimetric SAR

A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation

SAR Satellite Imagery Reveals the Impact of the Covid-19 Crisis on Ship Frequentation in the French Mediterranean Waters

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