Nonparametric Segment Detection

In computer and robotic vision point clouds from depth sensorshave to be processed to form higher-level concepts such as lines,planes, and objects. Bayesian methods formulate precisely prior knowledgewith respect to the noise and likelihood of points given a line, plane,or object. Nonparametric methods also formulate a prior with respectto the number of those lines, planes, or objects. Recently, a nonparametricBayesian method has been proposed to perform optimal inferencesimultaneously over line fitting and the number of lines. In this paperwe propose a nonparametric Bayesian method for segment fitting. Segmentsare lines of finite length. This requires 1.) a prior for line segmentlengths: the symmetric Pareto distribution, 2.) a sampling method thathandles nonconjugacy: an auxiliary variable MCMC method. Resultsare measured according to clustering performance indicators, such asthe Rand Index, the Adjusted Rand Index, and the Hubert metric. Surprisingly,the performance of segment recognition is worse than that ofline recognition. The paper therefore concludes with recommendationstowards improving Bayesian segment recognition in future w

Taxonomia e variação geográfica das espécies do gênero Alouatta Lacépède (Primates, Atelidae) no Brasil Taxonomy and geographic variation of species of the genus Alouatta Lacépède (Primates, Atelidae) in Brazil

Neste estudo analisou-se a variação geográfica e não-geográfica de táxons de bugios, gênero Alouatta Lacépède, 1799, que ocorrem no Brasil, com o objetivo de esclarecer a taxonomia do grupo. Para a análise morfológica, examinou-se um total de 1.286 espécimes mantidos em cinco museus brasileiros e dois norte-americanos. O material consistiu basicamente de peles, crânios e ossos hióides; esqueletos e espécimes preservados em via úmida foram escassos. O estudo se baseou na análise qualitativa dos complexos morfológicos em adição a 18 morfométicos do crânio e osso hióide. Antes das decisões taxonômicas, elaborou-se um estudo de variação geográfica, sexual, ontogenética e individual. Reconheceu-se 10 espécies de Alouatta ocorrendo no Brasil, sendo a maioria definida por caracteres discretos, porém diagnósticos. São elas: Alouatta caraya (Humboldt, 1812), A. fusca (Geoffroy Saint-Hilaire, 1812), A. clamitans Cabrera, 1940, A. belzebul (Linnaeus, 1766), A. discolor (Spix, 1823), A. ululata Elliot, 1912; A. juara (Linnaeus, 1766), A. macconnelli (Humboldt, 1812), A. puruensis Lönnberg, 1941 e A. nigerrima Lönnberg, 1941. Alouatta macconnelli e A. clamitans mostraram notável variação geográfica na coloração da pelagem e algumas variáveis morfométricas (polimorfismo) o que dificultou as definições e limites dos táxons. Alouatta belzebul apresentou variação em mosaico na coloração da pelagem. Alouatta ululata e A. puruensis foram definidas pela presença de dicromatismo sexual na pelagem, mas este caráter pode ser um artefato e necessita estudos adicionais para corroborar sua validade. Sinonimizou-se Alouatta belzebul mexianae Hagmann, 1908 com A. discolor; e a validade de Alouatta seniculus amazonica Lönnberg 1941, não foi considerada.<br>In this monograph, was studied non-geographic and geographic variation of taxa of Howling Monkeys, genus Alouatta Lacépède, 1799, occuring in Brazil, in order to solve the taxonomy of the group. For the morphological analysis, were examined a total of 1,286 specimens kept in five Brazilian and two North-American museums. The material consisted mostly of skin, skull and hyoid bone; skeleton or fluid-preserved specimens were scarse. The study was based on qualitative analysis of the morphological complexes in addition 18 morphometric characters of the skull and hyoid bone. Prior to making taxonomic decisions, was conducted a study of geographic, sexual, ontogenetic, and individual variation. Were recognized ten species of Alouatta occuring in Brazil and most of them were defined by discrete, but diagnostic characters. The species are: Alouatta caraya (Humboldt, 1812), A. fusca (Geoffroy Saint-Hilaire, 1812), A. clamitans Cabrera, 1940, A. belzebul (Linnaeus, 1766), A. discolor (Spix, 1823), A. ululata Elliot, 1912; A. juara (Linnaeus, 1766), A. macconnelli (Humboldt, 1812), A. puruensis Lönnberg, 1941, and A. nigerrima Lönnberg, 1941. Alouatta macconnelli and A. clamitans showed noticeable geographic variation on pelage coloration and some morphometric characters (polymorphism) difficulting their definition and geographic limits. Alouatta belzebul presented an accentuated geographic mosaic variation on coat coloration. Alouatta ululata and A. puruensis were defined in presenting sexual dicromism on pelage, but this character can be an artefate due the small sample and both taxa need further studies to confirm their validity. Alouatta belzebul mexianae Hagmann, 1908 was sinonimized with A. discolor; and the validity of Alouatta seniculus amazonica Lönnberg 1941 was not considered