Lineal perspective estimation on monocular images

Depth estimation from monocular images can be retrieved from the perspective distortion. One major e ect of this distortion is that a set of parallel lines in the real world converges into a single point in the image plane. The estimation of the coordinates of the vanishing point can be retrieved directly by di erent ways, like Hough Transform and First derivative approaches. Many of them work on speci c real scene characteristics and often lead to spurious vanishing points. Technology and computational advances suggest that some re nements to these simple techniques or a combination of them could lead to more con dent vanishing point detection than modelling and developing a new complicated ones. In this paper we study the behaviour of two classical approaches, introduce them some improvements and propose a new combinational technique to estimate the location of the vanishing point in an image. The solutions will be described and compared, also through the discussion of the results obtained from their application to real images.Presentado en el VIII Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Lineal perspective estimation on monocular images

Depth estimation from monocular images can be retrieved from the perspective distortion. One major e ect of this distortion is that a set of parallel lines in the real world converges into a single point in the image plane. The estimation of the coordinates of the vanishing point can be retrieved directly by di erent ways, like Hough Transform and First derivative approaches. Many of them work on speci c real scene characteristics and often lead to spurious vanishing points. Technology and computational advances suggest that some re nements to these simple techniques or a combination of them could lead to more con dent vanishing point detection than modelling and developing a new complicated ones. In this paper we study the behaviour of two classical approaches, introduce them some improvements and propose a new combinational technique to estimate the location of the vanishing point in an image. The solutions will be described and compared, also through the discussion of the results obtained from their application to real images.Presentado en el VIII Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Systematics and diversity of Neotropical ants.

With a long history of more than 100 million years and about 14,000 described living species, ants are one of the most important and well-known groups of insects in the world. Ants are key elements in the structure and dynamics of terrestrial systems, especially in the tropics, as well as models in studies of evolution, ecology, and monitoring of disturbed ecosystems. For all this, it is essential to know their history and phylogeny, in order among other things, to have a solid base for their systematics and taxonomy. Within Aculeata ants appear to be the sister group of Apoidea, and the ancestor of the Formicidae may have inhabited the northern hemisphere during the early Cretaceous. Since then, and especially since the Eocene, ants have spread throughout the planet, occupying almost all environments from forests to deserts. The Neotropical region has 137 genera and around 3,100 species of ants. The Neotropics seem to have been the “cradle” and “museum” of the groups of ants, which would explain their great diversity and a high degree of endemisms. This review describes the current state of knowledge of ants in the Neotropical region from a systematic point of view, with a synopsis of all supraspecific taxa described to date. Critical genera, problems to be solved, and perspectives for the study of these insects are also presented

Optical and Infrared Imaging and Spectroscopy of the Multiple-Shell Planetary Nebula NGC 6369

NGC 6369 is a double-shell planetary nebula (PN) consisting of a bright annular inner shell with faint bipolar extensions and a filamentary envelope. We have used ground- and space-based narrow-band optical and near-IR images, broad-band mid-IR images, optical long-slit echelle spectra, and mid-IR spectra to investigate its physical structure. These observations indicate that the inner shell of NGC 6369 can be described as a barrel-like structure shape with polar bubble-like protrusions, and reveal evidence for H2 and strong polycyclic aromatic hydrocarbons (PAHs) emission from a photo-dissociative region (PDR) with molecular inclusions located outside the bright inner shell. High-resolution HST narrow-band images reveal an intricate excitation structure of the inner shell and a system of "cometary" knots. The knotty appearance of the envelope, the lack of kinematical evidence for shell expansion and the apparent presence of emission from ionized material outside the PDR makes us suggest that the envelope of NGC 6369 is not a real shell, but a flattened structure at its equatorial regions. We report the discovery of irregular knots and blobs of diffuse emission in low-excitation and molecular line emission that are located up to 80" from the central star, well outside the main nebular shells. We also show that the filaments associated to the polar protrusions have spatial extents consistent with post-shock cooling regimes, and likely represent regions of interaction of these structures with surrounding material.Comment: 14 pages, 13 figures. Accepted for publication in MNRA

Morphological and genetic evidence supports the separation of two tapinoma ants (Formicidae, dolichoderinae) from the atlantic forest biome

The taxonomic boundaries of many Neotropical ant species of the genus Tapinoma are still unclear. Tapinoma atriceps and T. atriceps breviscapum are two morphologically similar taxa which occur sympatrically in the southern Atlantic Forest of Brazil. Some characters such as the scape length and head shape suggest that these taxa may be different species. We used DNA analysis and morphological evidence, including scanning electron microscopy, to evaluate the taxonomic validity of these taxa. We found distinct morphological characteristics that allow separating them as two different species, Tapinoma atriceps and Tapinoma breviscapum status novo, and this decision is supported by the DNA results, where Tapinoma atriceps was recovered as a lineage independent of T. breviscapum

Ants associated with dry forest fragments and urban environments in Santa Marta, Colombia

A publicly accessible database of ants associated with dry forest fragments and urban environments in Santa Marta, Colombia, is presented through the Colombian Biodiversity Information System (SIB). Capture methods included the installation of pitfall traps, protein and carbohydrate baits, extraction by the Winkler method of ants associated with leaf litter and manual collection of ants foraging on tree vegetation. The dataset contains 54 323 records, distributed in seven subfamilies, 42 genera, 88 species and nine morphospecies. This list is a tool to encourage the study and conservation of ants in urban areas

Centro de Colecciones Biológicas de la Universidad del Magdalena (CBUMAG)

Colombia, con más de 50.000 especies conocidas en su territorio, es uno de los países con mayor diversidad biológica en el mundo, sin incluir la gran cantidad de microorganismos existentes. La evidencia de toda esta diversidad reposa en las colecciones biológicas y los museos de historia natural. Estos son espacios que albergan una inmensa cantidad de datos en la forma de ejemplares biológicos, debidamente organizados y clasificados, que son testigos de la biota en el planeta de diferentes épocas. En ellos podemos encontrar representantes de pequeños insectos, grandes vertebrados, todo tipo de plantas, microorganismos e incluso fósiles con miles de años de antigüedad. Toda esta información se hace disponible para su uso en investigaciones científicas, actividades académicas y divulgación del conocimiento a la sociedad

Distribución altitudinal de hormigas (Hymenoptera, Formicidae) en la vertiente noroccidental de la sierra nevada de santa marta (Colombia)

The composition and altitudinal distribution of ants along the northwestern slope of the Sierra Nevada de Santa Marta is described. A total of 40 genera and 136 species were collected; Myrmicinae was the richest subfamily at the generic and specific levels at all altitudes. Total ant richness and epigaeic ant richness decreases with altitude while the richness of litter ants was higher at intermediate altitudes. Despite the high level of species turnover along the altitude gradient, the dominance of taxa with low abundance at all altitudes suggests similar ecological elements along the gradient but especially in the three higher altitudes. On the other hand, species turnover, abundancebased similarity, and incidence-based similarity suggest that ant fauna is divided into two major groups along the gradient, the first one is between 835 and 968 masl, and the second group is found between 1198 and 1395 masl. Ant fauna composition and distribution along the northwestern slope could be explained by Rapoport’s rule and the mid-domain effect.Se determinó la composición y distribución de las hormigas en un gradiente altitudinal dentro de la vertiente noroccidental de la Sierra Nevada de Santa Marta. Se recolectaron 40 géneros y 136 especies de hormigas; Myrmicinae fue la subfamilia con mayor número de géneros y especies para cada altitud. La riqueza total y la de hormigas epigeas disminuyeron significativamente con el incremento de la altitud, mientras que la riqueza de las hormigas que habitan en la hojarasca se concentró en las altitudes intermedias. Sólo la diversidad del ensamble de hormigas epigeas y tanto la diversidad como la equidad de las especies de la hojarasca, tendió a disminuir significativamente al incrementar la altitud. A pesar del alto recambio de especies a lo largo del gradiente, el predominio de taxones con baja abundancia en todas las altitudes, sugiere elementos ecológicos similares en el gradiente, especialmente en las tres últimas altitudes. Por otra parte, los valores de recambio de especies, similitud basada en la abundancia y la incidencia de las especies, muestran que la fauna de hormigas a lo largo del gradiente está dividida en dos grupos, el primer grupo entre 835 y 968 msnm, el segundo entre 1198 y1395 msnm. La composición y la distribución de la fauna de hormigas que habitan a lo largo de la cuenca media de la vertiente Noroccidental de la SNMS, pueden ser explicadas a través de la regla de Rapoport y lo planteado en el efecto de altitudes intermedias

Detailed Studies of IPHAS sources. II. Sab 19, a true planetary nebula and its mimic crossing the Perseus Arm

The INT Photometric H$\alpha$ Survey (IPHAS) has provided us with a number of new-emission line sources, among which planetary nebulae (PNe) constitute an important fraction. Here we present a detailed analysis of the IPHAS nebula Sab\,19 (IPHASX\,J055242.8+262116) based on radio, infrared, and optical images and intermediate- and high-dispersion longslit spectra. Sab\,19 consists of a roundish 0.10 pc in radius double-shell nebula surrounded by a much larger 2.8 pc in radius external shell with a prominent H-shaped filament. We confirm the nature of the main nebula as a PN whose sub-solar N/O ratio abundances, low ionized mass, peculiar radial velocity, and low-mass central star allow us to catalog it as a type III PN. Apparently, the progenitor star of Sab\,19 became a PN when crossing the Perseus Arm during a brief visit of a few Myr. The higher N/O ratio and velocity shift $\simeq$40 \kms\ of the external shell with respect to the main nebula and its large ionized mass suggest that it is not truly associated with Sab\,19, but it is rather dominated by a Str\"omgren zone in the interstellar medium ionized by the PN central star.Comment: 12 pages, 8 figures, accepted for publication in MNRA

No foto realismo con esgrafiado

Cuando se crea una imagen para comunicar una idea, se está utilizando un lenguaje visual. Podemos “visualizar” nuestro pensamiento de la misma manera en que lo verbalizamos. Un diagrama, un mapa, una pintura son ejemplos del uso del lenguaje visual. Sus unidades estructurales son la línea, la forma, el color, el movimiento, la textura, entre otros. El arte pictórico ha demostrado que el uso de dichas unidades permite transmitir significados sin utilizar palabras. El área de No Foto realismo estudia la generación de imágenes que permitan la transmisión de mensajes visuales con expresión y estilo. En este trabajo, se presenta un prototipo de herramienta para la simulación de la técnica artística del Esgrafiado. La misma reúne elementos provenientes del área de la computación gráfica, el procesamiento de imágenes, el arte y la psicología cognitiva experimental, intentando brindar un medio para el desarrollo de habilidades de comunicación visual en un usuario observador así como también lo habilita al uso de los conceptos con otras herramientas para propósitos específicos a ámbitos no artísticos.A visual language is used when creating an image to communicate a subject. We can visualize our thinking as we can verbalize it. A diagram, a map, a painting are different examples of our visual language use. Line, shape, color, movement, texture, among others are their structural units, and pictorial art have shown their power for communicating messages without words. The Non Foto realism area studies the use of expresion and style in the creation of images for communicating visual messages. At this work, we present a prototype tool for the simulation of the artistic technique called Esgrafiado. The technique gathers elements from computer graphics, image processing, art and and experimental cognitive psychology trying to give a means for the development of visual communication skills to a user-observer. The technique enables the given concepts could be applied by the user into non artistic fields with specific subjects tools.V Workshop de Computación Gráfica, Imágenes Y VisualizaciónRed de Universidades con Carreras en Informática (RedUNCI