An study on re-identification in RGB-D imagery

[EN]Re-identi fication is commonly accomplished using appearance features based on salient points and color information. In this paper, we make an study on the use of di fferent features exclusively obtained from depth images captured with RGB-D cameras. The results achieved, using simple geometric features extracted in a top-view setup, seem to provide useful descriptors for the re-identi fication task.

Multitemporal analysis of satellite imagery: implementation of a land evolution model in ALCS (ATSR LAND CLASSIFICATION SYSTEM)

In this report it was designed an innovative satellite-based monitoring approach applied on the Iraqi Marshlands to survey the extent and distribution of marshland re-flooding and assess the development of wetland vegetation cover. The study, conducted in collaboration with MEEO Srl , makes use of images collected from the sensor (A)ATSR onboard ESA ENVISAT Satellite to collect data at multi-temporal scales and an analysis was adopted to observe the evolution of marshland re-flooding. The methodology uses a multi-temporal pixel-based approach based on classification maps produced by the classification tool SOIL MAPPER ®. The catalogue of the classification maps is available as web service through the Service Support Environment Portal (SSE, supported by ESA). The inundation of the Iraqi marshlands, which has been continuous since April 2003, is characterized by a high degree of variability, ad-hoc interventions and uncertainty. Given the security constraints and vastness of the Iraqi marshlands, as well as cost-effectiveness considerations, satellite remote sensing was the only viable tool to observe the changes taking place on a continuous basis. The proposed system (ALCS – AATSR LAND CLASSIFICATION SYSTEM) avoids the direct use of the (A)ATSR images and foresees the application of LULCC evolution models directly to „stock‟ of classified maps. This approach is made possible by the availability of a 13 year classified image database, conceived and implemented in the CARD project (http://earth.esa.int/rtd/Projects/#CARD).The approach here presented evolves toward an innovative, efficient and fast method to exploit the potentiality of multi-temporal LULCC analysis of (A)ATSR images. The two main objectives of this work are both linked to a sort of assessment: the first is to assessing the ability of modeling with the web-application ALCS using image-based AATSR classified with SOIL MAPPER ® and the second is to evaluate the magnitude, the character and the extension of wetland rehabilitation.

Cold cloud climatology over Europe and the Mediterranean during the warm season from Meteosat IR imagery

Thermal infrared (IR, 10.5 – 12.5 m) images from the Meteosat Visible and Infrared Imager (MVIRI) of cold cloud episodes (cloud top brightness temperature < 241 K) are used as a proxy of precipitating clouds to derive a warm season (May-August) climatology of their coherency, duration, span, and speed over Europe and the Mediterranean. The analysis focuses over the 30°-54°N, 15°W-40°E domain in May-August 1996-2005. Harmonic analysis using discrete Fourier transforms is applied together with a statistical analysis and an investigation of the diurnal cycle. This study has the objective to make available a set of results on the propagation dynamics of the cloud systems with the aim of assist numerical modellers in improving summer convection parameterization. The zonal propagation of cold cloud systems is accompanied by a weak meridional component confined to narrow latitude belts. The persistence of cold clouds over the area evidences the role of orography, the Pyrenees, the Alps, the Balkans and Anatolia. A diurnal oscillation is found with a maximum marking the initiation of convection in the lee of the mountains and shifting from about 1400 UTC at 40°E to 1800 UTC at 0°. A moderate eastward propagation of the frequency maximum from all mountain chains across the domain exists and the diurnal maxima are completely suppressed west of 5°W. The mean power spectrum of the cold cloud frequency distribution evidences a period of one day all over Europe disappearing over the ocean (west of 10°W). Other maxima are found in correspondence of 6 to 10 days in the longitudes from 15° W to 0° and indicate the activity of the westerlies with frontal passage over the continent. Longer periods activities (from 15 up to 30 days) were stronger around 10° W and from 5° W to 15° E and are likely related to the Madden Julian Oscillation influence. The maxima of the diurnal signal are in phase with the presence of elevated terrain and with land masses. A median zonal phase speed of 16.1 ms-1 is found for all events ≥ 1000 km and ≥ 20 h and a full set of results divided by years and recurrence categories is also presented.

A new information fusion method for land-use classification using high resolution satellite imagery

Satellite image classification involves designing and developing efficient image classifiers. With satellite image data and image analysis methods multiplying rapidly, selecting the right mix of data sources and data analysis approaches has become critical to the generation of quality land-use maps. In this study, a new postprocessing information fusion algorithm for the extraction and representation of land-use information based on high-resolution satellite imagery is presented. This approach can produce land-use maps with sharp interregional boundaries and homogeneous regions. The proposed approach is conducted in five steps. First, a GIS layer - ATKIS data - was used to generate two coarse homogeneous regions, i.e. urban and rural areas. Second, a thematic (class) map was generated by use of a hybrid spectral classifier combining Gaussian Maximum Likelihood algorithm (GML) and ISODATA classifier. Third, a probabilistic relaxation algorithm was performed on the thematic map, resulting in a smoothed thematic map. Fourth, edge detection and edge thinning techniques were used to generate a contour map with pixel-width interclass boundaries. Fifth, the contour map was superimposed on the thematic map by use of a region-growing algorithm with the contour map and the smoothed thematic map as two constraints. For the operation of the proposed method, a software package is developed using programming language C. This software package comprises the GML algorithm, a probabilistic relaxation algorithm, TBL edge detector, an edge thresholding algorithm, a fast parallel thinning algorithm, and a region-growing information fusion algorithm. The county of Landau of the State Rheinland-Pfalz, Germany was selected as a test site. The high-resolution IRS-1C imagery was used as the principal input data.

Imagery of a moving object: the role of occipital cortex and human MT/V5+

Visual imagery – similar to visual perception – activates feature-specific and category-specific visual areas. This is frequently observed in experiments where the instruction is to imagine stimuli that have been shown immediately before the imagery task. Hence, feature-specific activation could be related to the short-term memory retrieval of previously presented sensory information. Here, we investigated mental imagery of stimuli that subjects had not seen before, eliminating the effects of short-term memory. We recorded brain activation using fMRI while subjects performed a behaviourally controlled guided imagery task in predefined retinotopic coordinates to optimize sensitivity in early visual areas. Whole brain analyses revealed activation in a parieto-frontal network and lateral–occipital cortex. Region of interest (ROI) based analyses showed activation in left hMT/V5+. Granger causality mapping taking left hMT/V5+ as source revealed an imagery-specific directed influence from the left inferior parietal lobule (IPL). Interestingly, we observed a negative BOLD response in V1–3 during imagery, modulated by the retinotopic location of the imagined motion trace. Our results indicate that rule-based motion imagery can activate higher-order visual areas involved in motion perception, with a role for top-down directed influences originating in IPL. Lower-order visual areas (V1, V2 and V3) were down-regulated during this type of imagery, possibly reflecting inhibition to avoid visual input from interfering with the imagery construction. This suggests that the activation in early visual areas observed in previous studies might be related to short- or long-term memory retrieval of specific sensory experiences.

Neuronal Correlates of Perception, Imagery, and Memory for Familiar Tunes

We used fMRI to investigate the neuronal correlates of encoding and recognizing heard and imagined melodies. Ten participants were shown lyrics of familiar verbal tunes; they either heard the tune along with the lyrics, or they had to imagine it. In a subsequent surprise recognition test, they had to identify the titles of tunes that they had heard or imagined earlier. The functional data showed substantial overlap during melody perception and imagery, including secondary auditory areas. During imagery compared with perception, an extended network including pFC, SMA, intraparietal sulcus, and cerebellum showed increased activity, in line with the increased processing demands of imagery. Functional connectivity of anterior right temporal cortex with frontal areas was increased during imagery compared with perception, indicating that these areas form an imagery-related network. Activity in right superior temporal gyrus and pFC was correlated with the subjective rating of imagery vividness. Similar to the encoding phase, the recognition task recruited overlapping areas, including inferior frontal cortex associated with memory retrieval, as well as left middle temporal gyrus. The results present new evidence for the cortical network underlying goal-directed auditory imagery, with a prominent role of the right pFC both for the subjective impression of imagery vividness and for on-line mental monitoring of imagery-related activity in auditory areas.

Commentary on "Timbre as an Elusive Component of Imagery for Music" by Freya Bailes

The study of musical timbre by Bailes (2007) raises important questions concerning the relative ease of imaging complex perceptual attributes such as timbre, compared to more unidimensional attributes. I also raise the issue of individual differences in auditory imagery ability, especially for timbre.

When that tune runs through your head: A PET investigation of auditory imagery for familiar melodies

The present study used positron emission tomography (PET) to examine the cerebral activity pattern associated with auditory imagery forfamiliar tunes. Subjects either imagined the continuation of nonverbaltunes cued by their first few notes, listened to a short sequence of notesas a control task, or listened and then reimagined that short sequence. Subtraction of the activation in the control task from that in the real-tune imagery task revealed primarily right-sided activation in frontal and superior temporal regions, plus supplementary motor area(SMA). Isolating retrieval of the real tunes by subtracting activation in the reimagine task from that in the real-tune imagery task revealedactivation primarily in right frontal areas and right superior temporal gyrus. Subtraction of activation in the control condition from that in the reimagine condition, intended to capture imagery of unfamiliarsequences, revealed activation in SMA, plus some left frontal regions. We conclude that areas of right auditory association cortex, together with right and left frontal cortices, are implicated in imagery for familiartunes, in accord with previous behavioral, lesion and PET data. Retrieval from musical semantic memory is mediated by structures in the right frontal lobe, in contrast to results from previous studies implicating left frontal areas for all semantic retrieval. The SMA seems to be involved specifically in image generation, implicating a motor code in this process.

When that tune runs through your head: a PET investigation of auditory imagery for familiar melodies

The present study used positron emission tomography (PET) to examine the cerebral activity pattern associated with auditory imagery for familiar tunes. Subjects either imagined the continuation of nonverbal tunes cued by their first few notes, listened to a short sequence of notes as a control task, or listened and then reimagined that short sequence. Subtraction of the activation in the control task from that in the real-tune imagery task revealed primarily right-sided activation in frontal and superior temporal regions, plus supplementary motor area (SMA). Isolating retrieval of the real tunes by subtracting activation in the reimagine task from that in the real-tune imagery task revealed activation primarily in right frontal areas and right superior temporal gyrus. Subtraction of activation in the control condition from that in the reimagine condition, intended to capture imagery of unfamiliar sequences, revealed activation in SMA, plus some left frontal regions. We conclude that areas of right auditory association cortex, together with right and left frontal cortices, are implicated in imagery for familiar tunes, in accord with previous behavioral, lesion and PET data. Retrieval from musical semantic memory is mediated by structures in the right frontal lobe, in contrast to results from previous studies implicating left frontal areas for all semantic retrieval. The SMA seems to be involved specifically in image generation, implicating a motor code in this process.

Effect of unilateral temporal-lobe excision on perception and imagery of songs

Auditory imagery for songs was studied in two groups of patients with left or right temporal-lobe excision for control of epilepsy, and a group of matched normal control subjects. Two tasks were used. In the perceptual task, subjects saw the text of a familiar song and simultaneously heard it sung. On each trial they judged if the second of two capitalized lyrics was higher or lower in pitch than the first. The imagery task was identical in all respects except that no song was presented, so that subjects had to generate an auditory image of the song. The results indicated that all subjects found the imagery task more difficult than the perceptual task, but patients with right temporal-lobe damage performed significantly worse on both tasks than either patients with left temporal-lobe lesions or normal control subjects. These results support the idea that imagery arises from activation of a neural substrate shared with perceptual mechanisms, and provides evidence for a right temporal- lobe specialization for this type of auditory imaginal processing.

Mental scanning in auditory imagery for songs

Four experiments examined how people operate on memory representations of familiar songs. The tasks were similar to those used in studies of visual imagery. In one task, subjects saw a one word lyric from a song and then saw a second lyric; then they had to say if the second lyric was from the same song as the first. In a second task, subjects mentally compared pitches of notes corresponding to song lyrics. In both tasks, reaction time increased as a function of the distance in beats between the two lyrics in the actual song, and in some conditions reaction time increased with the starting beat of the earlier lyric. Imagery instructions modified the main results somewhat in the first task, but not in the second, much harder task. The results suggest that song representations have temporal-like characteristics. (PsycINFO Database Record (c) 2012 APA, all rights reserved)