## The AIM@SHAPE Glossary

### Alphabetical list of terms

- object joint
- Analogous to the joint node (Human joint), but adapted to describe smart objects.
- object segment
- Node specialization for Smart Objects structural descriptors. It contains information about each object part, including the geometry and a pointer to additional smart object attributes.
- occlusion
- A portion of a surface is occluded to a sensor when there is a closer object hiding it to the sensor.
- offset surface
- Coefficient set of points at a given distance of a given shape following the oriented normal to the input shape. It is a frequently used method for surface creation in CAD; if self-intersections occur, the offset has to be trimmed.
- ontology
- The specification of a conceptualisation of a knowledge domain. In philosophy (from the Greek “on” = being/to be and “logos” = word/speech) it is the science or study of being or existence as well as the basic categories thereof -- trying to find out what entities and what types of entities exist. In computer science, an ontology is the product of an attempt to formulate an exhaustive and rigorous conceptual schema about a domain. An ontology is typically a hierarchical data structure containing all the relevant entities and their relationships and rules within that domain (e.g. a domain ontology).. On the Web, the term applies to the many ongoing efforts to develop topic-specific sets of XML-friendly language, rules and definitions. Essentially, IT ontologies are logical supersets that combine metadata, taxonomies and semantics into formal systems that can be encoded in software, enabling diverse Web applications to truly understand one another.
- orientable surface
- A two-dimensional manifold surface is orientable if a consistent concept of clockwise rotation can be defined on the surface in a continuous manner. This turns out be equivalent to the question of whether the surface contains no subset that is homeomorphic to the M?bius band. In an equivalent definition, a surface is called orientable if there exists an atlas on it such that the Jacobian of all the transition functions (that is the homeomorphisms defined on the intersections of each pair of charts) from a chart to another are positive for all the intersecting pairs of regions.
- oriented surface
- A manifold surface throughout which left and right-directions are globally defined. From a mathematical point of view, this means that a differential form of degree 2 which is nonzero at every point on the surface is given.
- orthogonal projection
- Projection P applied to x such that P(x)-x is in normal direction of P(x).
- orthotomic
- The orthotomic of a given curve/surface is the set of reflections of a given point around the tangents of a the curve/surface.
- out-of-core
- When a problem is too large to fit into the primary memory (both physical and virtual) of the computer, it has to be processed using out of core techniques.

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