An attempt to push back frontiers – digital near-ultraviolet aerial archaeology

Verhoeven, Geert; Schmitt, Klaus

doi:10.1016/j.jas.2009.11.013

Cited by 33 publications

(18 citation statements)

References 39 publications

(61 reference statements)

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“…Stone buildings have been constructed since the 13th century when the structure of contemporary settlements was established in the Czech Republic, thus ruins of stone buildings cannot be recorded in the sub-soil of contemporary arable fields. This highly contrasts with areas of the former Roman Empire, and Provinces where stone buildings were frequently constructed and therefore negative cropmarks on field crops can be recorded more frequently (see Evans and Jones, 1977;Doneus, 2001;Hanson and Oltean, 2003;Fassbinder, 2010;Verhoeven and Schmitt, 2010).…”

Section: Discussionmentioning

confidence: 92%

Cropmarks in main field crops enable the identification of a wide spectrum of buried features on archaeological sites in Central Europe

Gojda

Hejcman

2012

Journal of Archaeological Science

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Section: Discussionmentioning

confidence: 92%

Cropmarks in main field crops enable the identification of a wide spectrum of buried features on archaeological sites in Central Europe

Gojda

Hejcman

2012

Journal of Archaeological Science

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“…1b), we used a Nikon D70 digital SLR camera (Tokyo, Japan) fitted with a Nikon UV Nikkor f4.5/105 mm lens and a Baader U-Filter (Baader Planetarium, Germany: 310-390 nm UV transmission) mounted on a Nikon AF-1 gel filter holder. The transmission function of the Baader U-filter can be found in Verhoeven & Schmitt (2010), confirming that this lens transmits the UV exclusively, with no significant transmittance in any other spectral domain. To completely prohibit any long-wave contamination (including in the IR), we used a high power chip type UV LED (l max = 365 nm; model: NCSU033A(T), Nichia Corporation, Tokushima, Japan) as a light source.…”

Section: Spectral Reflectance Measurements Of Bee Colour Coatsmentioning

confidence: 56%

Effects of aposematic coloration on predation risk in bumblebees? A comparison between differently coloured populations, with consideration of the ultraviolet

Stelzer

Raine

Schmitt³

et al. 2010

Journal of Zoology

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It has been proposed that sympatric bumblebee species form mimicry rings to profit from learnt avoidance behaviour by predators. This hypothesis can be tested by comparing the predation rates of local bumblebees with those of imported nonnative bumblebees, whose coat colour is different from that of local bees, so that their coloration is unfamiliar to local predators. To test whether populations of non-native bumblebees suffer higher worker loss rates during foraging, we conducted transplant experiments in the UK, Germany and Sardinia. The loss rates of foraging workers of four Bombus terrestris populations (Bombus terrestris canariensis, Bombus terrestris terrestris, Bombus terrestris sassaricus and Bombus terrestris dalmatinus) were compared, evaluating data from 989 foragers, whose flight times were monitored precisely (over 8258 h of foraging). While all of these workers display a bright UV-reflecting abdominal tip, the colours in other body parts differ strongly to the eyes of avian predators. The hypothesis that foragers from the non-native bumblebee populations, which differ in coloration from the local native population, would suffer higher predation risk was not upheld. In contrast, in one location (Sardinia) the native population had the highest loss rate. The consistent population rank order we found in terms of forager losses indicates that such losses are more prominently affected by factors other than the familiarity of local predators with aposematic colour patterns.

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“…The configuration of the system proposed demonstrated the capability of generating vigor maps with NIR vision. Despite a few publications related to the detection of vegetation in the UV band (Hahn, 2009;Verhoeven & Schmitt, 2010), its applicability for the objectives set and the nature of the environments tested did not meet the expected requirements. In particular, unhealthy vines affected by downey mildew (Plasmopara viticola) and stained on the leaves by oily spots were not detected by the UV-based vision system, leaving this research topic completely opened.…”

Section: Discussionmentioning

confidence: 93%

“…Despite these drawbacks, there have been several studies focused on UV perception. Verhoeven & Schmitt (2010) recommend taking images in this band from a low altitude -under 300 m-to avoid the negative effect of dispersion. However, closeness to the vegetation must be balanced according to Hahn (2009), who remarks the importance of studying main crop parameters to a field level against an individual level, as it is known that canopy properties change if they are stud-…”

Section: Segmentación Automática De Imágenes Digitales Para Estimar Ementioning

confidence: 99%

Segmentación automática de imágenes digitales para estimar el vigor en viñas

Sáiz-Rubio¹,

Rovira-Más²

2012

Span. j. agric. res.

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The geographic information required to implement precision viticulture applications in real fields has led to the extensive use of remote sensing and airborne imagery. While advantageous because they cover large areas and provide diverse radiometric data, they are unreachable to most of medium-size Spanish growers who cannot afford such image sourcing. This research develops a new methodology to generate globally-referenced vigor maps in vineyards from ground images taken with a camera mounted on a conventional tractor. This monocular camera was able to sense in the visible, NIR, and UV spectra, selectively isolated with bandpass filters. The versatility of the system was further enhanced by implementing two sampling levels: intensive coverage of 1 m 2 and super-intensive for 0.1 m 2 . The core of the procedure resides in the algorithm for automatically segmenting the filtered images in such a way that relative differences in canopy vigor were objectively quantified. The calculation of the dynamic threshold involved the mathematical concepts of gradient and curvature. Field results showed that relative differences in vine vigor can be detected from NIR-filtered images and intensive sampling. Furthermore, individual images were successfully merged into a global vigor map that can be directly employed by end-users. Super-intensive sampling and UV perception were not appropriate for building vigor maps, but could be of interest for other agronomical purposes as the early detection of diseases. Field tests proved the feasibility of building global vigor maps from ground-based imagery, and showed the potential of this technique as a predictive instrument for modest-size producers.Additional key words: dynamic threshold; GPS; NIR; precision viticulture; UV; vigor map. Resumen Segmentación automática de imágenes digitales para estimar el vigor en viñasLa información requerida para implementar aplicaciones de viticultura de precisión en parcelas reales ha desembocado en el uso extensivo de la teledetección y la detección aérea. Si bien estos métodos son ventajosos por cubrir vastas áreas y proveer diversa información radiométrica, suelen ser inalcanzables para el productor español medio debido a los gastos ocasionados. Esta investigación desarrolla una nueva metodología para generar mapas de vigor con referencias globales basados en imágenes digitales tomadas con una cámara montada sobre un tractor convencional y con capacidad para percibir en el espectro visible, infrarrojo cercano (NIR) y ultravioleta (UV). Para hacer el sistema más versátil se analizaron dos niveles de muestreo: intensivo (1 m 2 de cobertura vegetal) y super-intensivo (0,1 m 2 de cobertura). El núcleo de la metodología propuesta se basa en el algoritmo de segmentación de imágenes para cuantificar automáticamente diferencias en vigor vegetativo. El cálculo del umbral dinámico se fundamenta en los conceptos matemáticos de gradiente y curvatura. Los resultados obtenidos mostraron que es posible cuantificar diferencias en vigor vegetativo de viña...

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An attempt to push back frontiers – digital near-ultraviolet aerial archaeology

Cited by 33 publications

References 39 publications

Cropmarks in main field crops enable the identification of a wide spectrum of buried features on archaeological sites in Central Europe

Cropmarks in main field crops enable the identification of a wide spectrum of buried features on archaeological sites in Central Europe

Effects of aposematic coloration on predation risk in bumblebees? A comparison between differently coloured populations, with consideration of the ultraviolet

Segmentación automática de imágenes digitales para estimar el vigor en viñas

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