A new method has been designed to identify and locate objects lying on a flat surface. The merit of the approach is to provide strong robustness to partial occlusions (due for instance to uneven lighting conditions, shadows, highlights, touching and overlapping objects) thanks to a local and compact description of the objects boundaries and to a new fast recognition method involving generation and recursive evaluation of hypotheses named HYPER (HY potheses Predicted and Evaluated Recursively). The method has been integrated within a vision system coupled to an indutrial robot arm, to provide automatic picking and repositioning of partially overlapping industrial parts.

https://hal.inria.fr/inria-00615534/document

HYPER: A New Approach for the Recognition and Positioning of Two-Dimensional Objects

We present a new approach to the stereo-matching problem. Images are individually described by aneighborhood graph of line segments coming from a polygonal approximation of the contours. The matching process is defined as the exploration of the largest components of adisparity graph built from the descriptions of the two images, and is performed by an efficient prediction and propagation technique. This approach was tested on a variety of man-made environments, and it appears to be fast and robust enough for mobile robot navigation and three-dimensional part-positioning applications.

https://hal.inria.fr/inria-00615533/document

Efficient registration of stereo images by matching graph descriptions of edge segments

The invention provides methods and systems for analyzing seismic data. In one method, a set of three-dimensional seismic signal traces (36) are provided. A reference (30) of one of the traces is compared (40) with at least two neighboring traces to find a neighbor trace with the least or most similarity to the reference trace. This neighbor trace is defined as a target trace. The reference trace is then compared (42) with the target trace to produce a comparison value which is saved (44) for later output (52) or display (48).

Methods and apparatus for analyzing seismic data

In this paper, we present an automatic horizonpicking algorithm, based on a surface detection technique, to detect horizons in 3D seismic data. The surface detection technique, and the use of 6-connectivity, allows us to detect fragments of horizons that are afterwards combined to form full horizons. The criteria of combining the fragments are similarity of orientation of the fragments, as expressed by their normal vectors, and proximity using 18-connectivity. The identified horizons are interrupted at faults, as required by the experts.

Horizon picking in 3D seismic data volumes

Most seismic stratigraphic or seismic lithologic interpretations have been applied to clastic depositional systems. Because of their unique sedimentologic and mineralogic characteristics, carbonate rocks are more difficult to study using seismic data. Increased knowledge of carbonate deposits and their petrophysical parameters, and higher quality geophysical tools now permit a better understanding of carbonate rocks using seismic images. In this paper, seismic facies of carbonate rocks are characterized, step by step, from the basin to the supratidal environment. (1) Pelagic deposits (shales and micritic limestone layers) exhibit continuous, parallel reflections with an apparently high frequency. Chalk deposits display continuous high-amplitude reflections at the top and base with an internal reflection-free zone. (2) Talus deposits are characterized by discontinuous, oblique reflections of high amplitude. Carbonate debris flow generates chaotic reflections with hummocky surfaces. Channels exhibit erosional truncations. (3) Reef barriers are mound-shaped biogenic deposits that display marginal onlapping reflections. Overlying reflections drape the reefs, and underlying reflections exhibit pull-up or pull-down effects. Hyperbolic diffractions also may occur. (4) Platform border sands are mound-shaped oblique reflections of moderately high amplitude. (5) Inner shelf strata are characterized by parallel, continuous reflections typically displaying low frequency. Patch reefs may be distinguished within the inner shelf system (mound shape, drape of overlying reflections, velocity anomalies, and spurious events). (6) Where dolomitized, the intertidal to supratidal facies exhibit a "marbled" zone--a practically reflection-free zone with a few discontinuous reflections. Diagenetic events, such as paleokarst zones, may be delineated using special analyses involving amplitude offset variations. The study of carbonate depositional environments and petrophysical characteristics provides a more complete geologic insight, including relative changes in sea level, within a sedimentary basin. Such studies are fundamental in analyzing carbonate reservoirs and their paleogeographic settings.

Seismic Interpretation of Carbonate Depositional Environments

We show how the techniques of Digital Image Analysis can be efficiently used to help in the interpretation of seismic cross-sections. The problem of automatically finding homogeneous facies is in fact directly tied to Image Processing problems such as edge detection, texture analysis, segmentation and classification. We briefly overview some existing tools, outline some new techniques which had to be invented to cope with the characteristics of seismic signals and demonstrate on many examples the power of our approach.

O. Faugeras

Papers

Application of image analysis techniques to seismic data