arXiv subjects

Amelia Carolina Sparavigna

Publications and source records attributed to Amelia Carolina Sparavigna.

125 records · Page 7Linked to original sources

arXiv2010

Arabia: from craters to stone circles

The Arabia Shield has a volcanic nature inside. A region of the Western Saudi Arabia is in fact covered with vast fields of lava known as harraat. These lands are spotted by many stone circles and other quite interesting archaeological remains of the Neolithic period, such as the "desert kites", the hunters used to guide the game across the harrah in some corrals. With Google Maps, we can observe both sceneries, the volcanic nature of the land and a portrait of Arabia during the Neolithic times.

physics.geo-ph↗

arXiv2010

The Titicaca basin: a paradigmatic region for multidisciplinary studies

We propose a survey of the literature about archaeological and geophysical researches and on the paleoclimatology of the basin of Titicaca Lake, in connection with the agricultural system of the raised fields. Here again we discuss the use of Google Maps and satellite imagery as fundamental tools to understand this ancient agricultural system and its role in the history of pre-Incaic cultures.

physics.geo-ph↗

arXiv2010

Andean terraced hills (a use of satellite imagery)

The aim of this paper is in stimulating the use of satellite imagery, in particular the free service of Google Maps, to investigate the distribution of the agricultural technique of terraced hills in Andean countries, near Titicaca Lake. In fact, satellite maps can give a clear view of the overall surface modified by human work, being then a precious help for on-site archaeological researches and for historical analysis. Satellite imagery is also able to give the distribution of burial and worship places. The paper discusses some examples near the Titicaca Lake.

physics.geo-ph↗

arXiv2010

Geoglyphs of Titicaca as an ancient example of graphic design

The paper proposes an ancient landscape design as an example of graphic design for an age and place where no written documents existed. It is created by a network of earthworks, which constitute the remains of an extensive ancient agricultural system. It can be seen by means of the Google satellite imagery on the Peruvian region near the Titicaca Lake, as a texture superimposed to the background landform. In this texture, many drawings (geoglyphs) can be observed.

cs.GR↗

arXiv2010

Symbolic landforms created by ancient earthworks near Lake Titicaca

Interesting landforms created by an ancient network of earthworks are shown, using Google satellite imagery enhanced by an image processing. This network covers a large part of the land near the Titicaca Lake. Satellite images clearly display the slopes of hills criss-crossed with terrace walls and the surfaces of the plains covered with raised fields, indicating that this was once a highly productive agricultural place for the south central Andes. Some of the landforms are rather remarkable, having a clear symbolic function. Among them, there are structures which seem to represent birds, where ponds are their eyes.

physics.geo-ph↗

arXiv2010

Enhancing the Google imagery using a wavelet filter

In some previous papers we proposed the use of free software for a processing of the Google satellite imagery. Here we discuss the use of a wavelet filter for the same purposes. This filter is a tool included in a freely downloadable software (Iris), well-known for the processing of astronomical images. Combining the image obtained after applying the wavelet filter, with an image created with Gimp and AstroFracTool, the visibility of the landforms, as obtained from Google Maps, is strongly increased. Among several possible examples, we proposed a crater, a paleochannel and the Great Bend of the Nile.

physics.geo-ph↗

arXiv2010

Small simple impact craters

The paper discusses some examples of image processing applied to improve optical satellite imagery of small craters (Kamil, Veevers, Haviland). The examples show that image processing can be quite useful for further in-situ researches, because the resultant imagery helps to have a better picture of the crater shape and of the distribution of debris about it. The paper is also disclosing an interesting underwater structure, with shape and size of a small crater, located on the coast-line of Sudan.

physics.geo-ph↗

arXiv2010

Craters and ring complexes of the North-East Sudanese country

We propose a survey of a rocky region in the north-east part of Sudan, using the satellite imagery from Google Maps. In particular we analyse the region which lies to the north of Nakasib Suture. Images reveal craters and ring complexes. To enhance their features, images are processed with a method based on fractional calculus. Two of these structures are proposed as possible impact craters.

physics.geo-ph↗

arXiv2010

Crater-like landform in Bayuda desert (a processing of satellite images)

The paper is proposing a survey of a region in Sudan, the Bayuda desert, using the satellite images as obtained from Google Maps. The images reveal the ring granitic structure of the region enclosed by a bend of river Nile. To enhance the features of the landform, images are processed with a method based on fractional calculus, able to increase the rendering of edges without deteriorating the overall quality of images. Besides the ringed structure of the region, a huge crater-like structure with a diameter of 10 km is evidenced.

physics.geo-ph↗

arXiv2010

A comment on Eta Carinae's Homunculus Nebula imaging

Homunculus Nebula is surrounding the star system Eta Carinae. The nebula is embedded within a much larger ionized hydrogen region, which is the Carina Nebula. Homunculus is believed to have been ejected in a huge outburst from Eta Carinae in 1841, so brightly to be visible from Earth. This massive explosion produced two polar lobes and an equatorial disc, moving outwards. Though Eta Carinae is quite away, approximately 7,500 light-years, it is possible to distinguish in the nebula, many structures with the size of about the diameter of our solar system. Knots, dust lanes and radial streaks appear quite clearly in many images. In this paper, we compare the imaging of Homunculus Nebula has obtained by HST and Gemini South Telescope research teams. We use some processing methods, to enhance some features of the structure, such as the color gradient, and knots and filaments in the central part of the nebula.

astro-ph.SR↗

arXiv2010

Tuning CLD Maps

The Coherence Length Diagram and the related maps have been shown to represent a useful tool for image analysis. Setting threshold parameters is one of the most important issues when dealing with such applications, as they affect both the computability, which is outlined by the support map, and the appearance of the coherence length diagram itself and of defect maps. A coupled optimization analysis, returning a range for the basic (saturation) threshold, and a histogram based method, yielding suitable values for a desired map appearance, are proposed for an effective control of the analysis process.

cs.CV↗

arXiv2010

CLD-shaped Brushstrokes in Non-Photorealistic Rendering

Rendering techniques based on a random grid can be improved by adapting brushstrokes to the shape of different areas of the original picture. In this paper, the concept of Coherence Length Diagram is applied to determine the adaptive brushstrokes, in order to simulate an impressionist painting. Some examples are provided to instance the proposed algorithm.

cs.CV↗

arXiv2009

Non-photorealistic image processing: an Impressionist rendering

The paper describes an image processing for a non-photorealistic rendering. The algorithm is based on a random choice of a set of pixels from those ot the original image and substitution of them with colour spots. An iterative procedure is applied to cover, at a desired level, the canvas. The resulting effect mimics the impressionist painting and Pointillism.

cs.CV↗

arXiv2009

Astronomical image processing based on fractional calculus: the AstroFracTool

The implementation of fractional differential calculations can give new possibilities for image processing tools, in particular for those that are devoted to astronomical images analysis. As discussed in arxiv:0910.2381, the fractional differentiation is able to enhance the quality of images, with interesting effects in edge detection and image restoration. Here, we propose the AstroFracTool, developed to provide a simple yet powerful enhancement tool-set for astronomical images. This tool works evaluating the fractional gradient of an image map. It can help produce an output image useful for further research and scientific purposes, such as the detection of faint objects and galaxy structures, or, in the case of planetary studies, the enhancement of surface details.

astro-ph.IM↗

arXiv2009

Using fractional differentiation in astronomy

In a recent paper, published at arXiv:0910.2381, we started a discussion on the new possibilities arising from the use of fractional differential calculus in image processing. We have seen that the fractional calculation is able to enhance the quality of images, with interesting possibilities in edge detection and image restoration. Here, we want to discuss more deeply its role as a tool for the processing of astronomical images. In particular, the fractional differentiation can help produce a 'content-matter' based image from a pretty astronomical image that can be used for more research and scientific purposes, for instance to reveal faint objects galactic matter, nebulosity, more stars and planetary surface detail.

astro-ph.IM↗

arXiv2009

Ringed spherulitic and undulated textures in the nematic phase of a mixture of trans-4-hexylcyclohexanecarboxylic and benzoic acids

We present a polarising optical microscopy study of a liquid-crystal mixture of trans-4-hexylcyclohexanecarboxylic acid (C6) and benzoic acid. Both materials have carboxylic groups that can form dimers through hydrogen bonding. The mixture is nematic and room temperature and has the clearing point at 88 Celsius. The nematic phase shows ringed spherulites, sometimes looking like spiral structures, and undulated textures, which remain visible heating the sample till 71 Celsius. This is the temperature of a texture transition inside the nematic phase.

cond-mat.soft↗

arXiv2009

Symmetries in Images on Ancient Seals

We discuss the presence of symmetries in images engraved on ancient seals, in particular on stamp seals. Used to stamp decorations, to secure the containers from tampering and for owner's identification, we can find seals that can be dated from Neolithic times. Earliest seals were engraved with lines, dots and spirals. Nevertheless, these very ancient stamp seals, in the small circular or ovoid space of their bases, possess bilateral and rotational symmetries. The shape of the base seems to determine the symmetries of images engraved on it. We will also discuss what could be the meaning of antisymmetry and broken symmetry for images on seals.

math.HO↗