Search results for "DCOM"
showing 10 items of 984 documents
Space-Frequency Quantization for Image Compression With Directionlets
2007
The standard separable 2-D wavelet transform (WT) has recently achieved a great success in image processing because it provides a sparse representation of smooth images. However, it fails to efficiently capture 1-D discontinuities, like edges or contours. These features, being elongated and characterized by geometrical regularity along different directions, intersect and generate many large magnitude wavelet coefficients. Since contours are very important elements in the visual perception of images, to provide a good visual quality of compressed images, it is fundamental to preserve good reconstruction of these directional features. In our previous work, we proposed a construction of critic…
Interpretation of journalistic photographs as an instrument of visual literacy education
2016
Images are produced, used and distributed on an enormous scale. However, the skills of understanding, interpreting and using images as well as thinking and learning in terms of images are taken for granted, and thus, they are not sufficiently taught and developed, especially in higher education. The need for introducing visual literacy into the curriculum was identified in late 1960s, but no concrete guidelines have followed. This study proposes to apply interpretation of journalistic photographs as an instrument of visual literacy education. The main focus is on the image interpretation process and the kinds of meanings viewers apply to a photograph in the interpretation process. In each o…
HIGH QUALITY TEXTURE MAPPING PROCESS AIMED AT THE OPTIMIZATION OF 3D STRUCTURED LIGHT MODELS
2019
Abstract. This article presents the evaluation of a pipeline to develop a high-quality texture mapping implementation which makes it possible to carry out a semantic high-quality 3D textured model. Due to geometric errors such as camera parameters or limited image resolution or varying environmental parameters, the calculation of a surface texture from 2D images could present several color errors. And, sometimes, it needs adjustments to the RGB or lightness information on a defined part of the texture. The texture mapping procedure is composed of mesh parameterization, mesh partitioning, mesh segmentation unwraps, UV map and projection of island, UV layout optimization, mesh packing and mes…
HYPERSPECTRAL REFLECTANCE SIGNATURES AND POINT CLOUDS FOR PRECISION AGRICULTURE BY LIGHT WEIGHT UAV IMAGING SYSTEM
2018
Abstract. The objective of this investigation was to study the use of a new type of a low-weight unmanned aerial vehicle (UAV) imaging system in the precision agriculture. The system consists of a novel Fabry-Perot interferometer based hyperspectral camera and a high-resolution small-format consumer camera. The sensors provide stereoscopic imagery in a 2D frame-format and they both weigh less than 500 g. A processing chain was developed for the production of high density point clouds and hyperspectral reflectance image mosaics (reflectance signatures), which are used as inputs in the agricultural application. We demonstrate the use of this new technology in the biomass estimation process, w…
3D MODELING FOR UNDERWATER ARCHAEOLOGICAL DOCUMENTATION: METRIC VERIFICATIONS
2018
Abstract. The survey in underwater environment has always presented considerable difficulties both operative and technical and this has sometimes made it difficult to use the techniques of survey commonly used for the documentation of Cultural Heritage in dry environment. The work of study concerns the evaluation in terms of capability and accuracy of the Autodesk123DCatch software for the reconstruction of a three-dimensional model of an object in underwater context. The subjects of the study are models generated from sets of photographs and sets of frames extracted from video sequence. The study is based on comparative method, using a reference model, obtained with laser scanner technique…
Breakthroughs in Photonics 2014: Recent Advances in 3-D Integral Imaging Sensing and Display
2015
Integral imaging concept provides a fascinating tool for the capture and display of 3-D images or movies with full parallax, with no need for special glasses and without visual fatigue due to the convergence and accommodation conflict. The limitations and recent advances in integral imaging are discussed.
3D RECONSTRUCTION-REVERSE ENGINEERING- DIGITAL FABRICATION OF THE EGYPTIAN PALERMO STONE USING BY SMARTPHONE AND LIGHT STRUCTURED SCANNER
2018
Abstract. This paper presents a pipeline that has been developed to acquire a shape with particular features both under the geometric and radiometric aspects. In fact, the challenge was to build a 3D model of the black Stone of Palermo, where the oldest Egyptian history was printed with the use of hieroglyphs. The dark colour of the material and the superficiality of the hieroglyphs' groove have made the acquisition process very complex to the point of having to experiment with a pipeline that allows the structured light scanner not to lose the homologous points in the 3D alignment phase. For the texture reconstruction we used a last generation smartphone.
3D RECONSTRUCTION OF THE ROMAN DOMUS IN THE ARCHAEOLOGICAL SITE OF LYLIBAEUM (MARSALA, ITALY)
2019
Abstract. Generally, terrestrial laser scanning surveys involve a rather large number of scans to ensure a high percentage of overlap required for the scan registration phase (target-based or point-based registration, cloud-to-cloud registration). These approaches result in data redundancy that could slow down both the acquisition and post-processing phases. In recent years, the technological evolution in the field of laser scanners has been directed to the development of devices that are able to perform an onsite pre-registration, to optimize the survey procedures and the reliability of the registration of the scan. The paper presents the results achieved during a terrestrial laser scannin…
SNAPSHOT SPECTRAL AND COLOR IMAGING USING A REGULAR DIGITAL CAMERA WITH A MONOCHROMATIC IMAGE SENSOR
2017
Spectral imaging (SI) refers to the acquisition of the three-dimensional (3D) spectral cube of spatial and spectral data of a source object at a limited number of wavelengths in a given wavelength range. Snapshot spectral imaging (SSI) refers to the instantaneous acquisition (in a single shot) of the spectral cube, a process suitable for fast changing objects. Known SSI devices exhibit large total track length (TTL), weight and production costs and relatively low optical throughput. We present a simple SSI camera based on a regular digital camera with (i) an added diffusing and dispersing phase-only static optical element at the entrance pupil (diffuser) and (ii) tailored compressed sensing…
A2Ba: Adaptive Background Modelling for Visual Aerial Surveillance Conditions
2015
International audience; Background modelling algorithms are widely used to define a part of an image that most time remains stationary in a video. In surveillance tasks, this model helps to recognize those outlier objects in an area under monitoring. Set up a background model on mobile platforms (UAVs, intelligent cars, etc.) is a challenging task due camera motion when images are acquired. In this paper, we propose A2Ba, a robust method to support instabilities caused by aerial images fusing different information about image motion. We used frame difference as first approximation, then age of pixels is estimated. This latter gives us an invariability level of a pixel over time. Gradient di…