The human vision system can discriminate regions which differ up to the second order statistics only. A lot of malignant tumours have boundaries which are not visible to the human eye. We present an algorithm designed...
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ISBN:
(纸本)0769522238
The human vision system can discriminate regions which differ up to the second order statistics only. A lot of malignant tumours have boundaries which are not visible to the human eye. We present an algorithm designed to reveal "hidden" boundaries in grey level images, by computing gradients in higher order statistics of the data. We demonstrate it by applying it to the identification of possible "hidden" boundaries of gliomas as manifest themselves in MRI 3d scans.
Archaeology is a destructive process in which accurate anddetailed recording of a site is imperative. As a site is exposed, documentation is required in order to recreate and understand the site,in context. We have d...
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ISBN:
(纸本)0769522238
Archaeology is a destructive process in which accurate anddetailed recording of a site is imperative. As a site is exposed, documentation is required in order to recreate and understand the site,in context. We have developed a 3d modeling pipeline that can assist archaeologists in the documentation effort by building rich, geometrically and photometrically accurate 3d models of the site. The modeling effort begins with data acquisition (images, range scans, GIS data, and video) and ends with the use of a sophisticatedvisualization tool that can be used by researchers to explore and understand the site. The pipeline includes new methods for shadow-based registration of 2d images and temporal change detection. Our multimodal augmented reality system allows users wearing head-tracked, see-through, head-worn displays to visualize the site model and associated archaeological artifacts, and to interact with them using speech and gesture.
In this paper we describe a vehicle borne data acquisition system for urban environments and associated3ddata management and interactive rendering software. The data acquisition system is capable of acquire 3ddata ...
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ISBN:
(纸本)0769522238
In this paper we describe a vehicle borne data acquisition system for urban environments and associated3ddata management and interactive rendering software. The data acquisition system is capable of acquire 3ddata from urban areas with centimetre resolution including automatic capturing of colour. The system includes a management and interactive rendering software which is designed to cope with the huge quantities of data generated by the acquisition system. It uses out-of-core pre-processing to transform data into octrees. Real-time interactive rendering is achieved by using novel techniques such as front-to-back octree traversal, occlusion query and speculative pre-fetching. The paper presents the results of the described techniques applied to large public areas including the City Centre of Verona, Italy.
We propose a new data structure, called Fan-Meshes (FM), for reconstructing 3d models and scenes represented by dense scanning point clouds. It is a local piecewise linear approximation to the data geometry, and can s...
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ISBN:
(纸本)0769522238
We propose a new data structure, called Fan-Meshes (FM), for reconstructing 3d models and scenes represented by dense scanning point clouds. It is a local piecewise linear approximation to the data geometry, and can serve as primitives in reconstruction with a good balance between computational loads and reconstruction quality. In our algorithm, local remeshing is performed in preprocessing to obtain regular FMs, and a three-level-point data structure called Triangle Selection Record (TSR) is then used to reduce redundancies in the raw data and overlapping in the original FMs. Furthermore, to apply the method to raw 3d scanning data, we use a smoothing operator to the point cloud in order to eliminate some sensor noises. Experimental results demonstrate that our scheme is effective even for large-scale scenes with real data.
A 3-dimensional (3-d) object modeling technique with mesh simplification and refinement based resolution adjustment is proposed in this paper. Polygonal models which are widely utilized in the modeling of 3-d objects ...
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ISBN:
(纸本)0769522238
A 3-dimensional (3-d) object modeling technique with mesh simplification and refinement based resolution adjustment is proposed in this paper. Polygonal models which are widely utilized in the modeling of 3-d objects are taken as basis, making use of the polygonal structure and vertex coordinates for the display of 3-d models. The amount of polygons and vertices of a model is proportional to the resolution as well as data quantity. In other words the resolution anddata increases with the number of polygons. In this paper, it is proposed to utilize resolution, and hence data amount, adjustable 3-d modeling so that model resolution and transmitteddata amount can be regulated according to access constraints.
This paper describes how a photogrammetry based3d capture system can be used as an input device for animation. The 3ddynamic Capture System is used to capture the motion of a human face which is extracted from a seq...
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ISBN:
(纸本)0769522238
This paper describes how a photogrammetry based3d capture system can be used as an input device for animation. The 3ddynamic Capture System is used to capture the motion of a human face which is extracted from a sequence of 3d models captured at TV frame rate. Initially the positions of a set of landmarks on the face are extracted. These landmarks are then used to provide motion data in two different ways. First, a high level description of the movements are extracted, and these can be used as input to a procedural animation package (i.e. CreaToon). Second the landmarks can be used as registration points for a conformation process where the model to be animated is modified to match the captured model. This approach gives a new sequence of models which have the structure of the drawn model but the movement of the captured sequence.
In a popular visual illusion, the portrait on paper currency is folded into an M shape along vertical lines through the nose and the eyes. When this folded picture is tilted back and forth horizontally the face underg...
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ISBN:
(纸本)0769522238
In a popular visual illusion, the portrait on paper currency is folded into an M shape along vertical lines through the nose and the eyes. When this folded picture is tilted back and forth horizontally the face undergoes striking changes in expression. This distortion reveals two insights concerning 3d representation in the human visual system and we have explored these with experiments on simple schematic faces and observations on distortions of laser range images of faces. The observations show first that when recovering depicteddepth, pictorial cues are interpreted independently of binocular depth information mid second, that the recovery of facial expression is based on a scaled prototypical face structure.
A new approach to face verification from 3ddata is presented. The method uses 3d registration techniques designed to work with resolution levels typical of the irregular point cloud representations provided by Struct...
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ISBN:
(纸本)0769522238
A new approach to face verification from 3ddata is presented. The method uses 3d registration techniques designed to work with resolution levels typical of the irregular point cloud representations provided by Structured Light scanning. Preprocessing using a-priori information of the human face and the Iterative Closest Point algorithm are employed to establish correspondence between test and target and to compensate for the non-rigid nature of the surfaces. Statistical modelling in the form of Gaussian Mixture Models is used to parameterise the distribution of errors in facial surfaces after registration and is employed to differentiate between intra- and extra-personal comparison of range images. An Equal Error Rate of 2.67% was achieved on the 30 subject manual subset of the the 3d_rma database.
As well known, in the reconstruction of the 3d models through optical systems, the errors are due to the single-view acquisition error and to the 3d modeling procedure. The latter can be ascribed to the various phases...
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ISBN:
(纸本)0769522238
As well known, in the reconstruction of the 3d models through optical systems, the errors are due to the single-view acquisition error and to the 3d modeling procedure. The latter can be ascribed to the various phases of the 3d modeling pipeline: pairwise registration, global registration, surface integration. This work examines the acquisition error as well as the errors due to an automatic procedure recently proposed for the 3d modeling of dental plaster casts. This contribution derives a simple error propagation model, rather useful for practical simulation purposes. From a general viewpoint, this contribution proposes a useful simulation of error propagation in 3d modeling, it shows the quality of an automatic 3d modeling procedure recently proposed and it shows the accuracy of 3d modeling dental plaster casts by current commercial range cameras an the considered automatic method.
We present a novel range sensing method that is capable of constructing accurate 3d models of specular objects. Our method utilizes a new range imaging concept called multi-peak range imaging, which accounts for the e...
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ISBN:
(纸本)0769522238
We present a novel range sensing method that is capable of constructing accurate 3d models of specular objects. Our method utilizes a new range imaging concept called multi-peak range imaging, which accounts for the effects of mutual reflections. False measurements generated by mutual reflections are then eliminated by applying a series of constraint tests based on local smoothness, global coordinate consistency and visibility consistency. We show the usefulness of our method by applying the method to three real objects with specular surfaces. The ground truth data for those three objects were also acquired in order to evaluate the elimination of false measurements and to justify the selection of the parameters in the constraint tests. Experimental results indicate that our method significantly improves upon the traditional methods for constructing reliable 3d models of specular objects with complex shapes.
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