## The AIM@SHAPE Glossary

### Alphabetical list of terms

- taxonomy
- From Greek “taxinomia” from the words “taxis” = arrangement/order and “nomos” = law, it refers to a hierarchical classification of things i.e. a classification system. Historically, the term has mostly been used in the life sciences to describe the rigorous classification of species. Whereas each biological species has a unique classification, information taxonomies are used to organize documents or content. Within the IT community, taxonomy is a hierarchical data structure or a type of classification schema.
- terrain
- See Topographic surface.
- tessellation
- Process forming or arranging continuous curves or surfaces in a piecewise, checked or mosaic pattern. In case of surfaces it is usually a triangulation.
- tetrahedral mesh
- A 3-dimensional simplicial mesh.
- tetrahedron bisection
- The action of replacing a tetrahedron ƒ? in a tetrahedral mesh with the two tetrahedra obtained by splitting ƒ? at the middle point of its longest edge through the plane passing through such point and the opposite edge of ƒ?. This rule is applied recursively to an initial decomposition of the cubic domain obtained by splitting it into six tetrahedra all sharing one diagonal.
- texture
- In computer graphics, the digital representation of the characteristic appearance of a surface having a tactile quality.
- thinning
- Process of removing pixels or voxels from a discretised pixel-based or voxel-based representation of an object for generating a representation consisting of connected, unit-wide paths of pixels or voxels.
- time-of-flight
- Scanning technology referring to devices that calculate distances (3D positions in space) by measuring the time of flight of very short pulses of light.
- tin
- See Triangulated Irregular Network.
- topograghic distance
- The topographic distance between two points p and q on a surface described by a C2-differentiable function defined over a domain D in R2 is the length of the path of steepest slope joining p and q.
- topographic surface
- The image of a real bivariate function f defined over a subset of points D in the Euclidean plane.
- topological graph
- A simple unlabeled graph whose connectivity is considered purely on the basis of topological equivalence, so that two edges (v1, v2) and (v2, v3) joined by a node v2 of degree two are considered equivalent to the single edge (v1, v3). This entity acts as a placeholder for a variety of structural descriptors. Topological graphs are different from the H-Anim or Smart Object skeletons, which are animation-oriented structures not suitable for other applications.
- triangle bisection
- The action of replacing a triangle t in a triangle mesh with the two triangles obtained by splitting t at the middle point of its longest edge through the segment passing through such point and the opposite vertex of t. This rule is applied recursively to an initial decomposition of a square obtained by splitting it into two triangles by one of its diagonals.
- triangle mesh
- A 2-dimensional simplicial mesh.
- triangulated irregular network (tin)
- A DTM based on the decomposition of the domain of a two-dimensional scalar field into a triangle mesh.
- triangulation
- Denoting |S| the topological space underlying a simplicial complex S, (|S| = ?y????S ??), then a triangulation of the topological space M is a case of simplicial complex S such that |S| = M. Improperly, the term triangulation is also used to denote the geometric realisation of a bi-dimensional simplicial complex (also known as triangle mesh); while tetrahedralisations are a subclass of three-dimensional simplicial complexes.
- trimmed patches
- A subset of an existing patch defined by a restriction by a trimming line of the parametric space of the parametric surface describing the existing patch.
- trimming an offset
- The operation of removing self-intersecting parts of offset surfaces. In fact, when the offset distance is larger than the minimal radius of curvature of the existing surface in some points and smaller in some others, some corresponding normals of the two surfaces will point in opposite directions causing self-intersections in the offset.
- trimming line
- Line creating a restriction of the parametric space, i.e. of the definition domain of a parametric surface (Bezier, B-Spline, NURBS...).
- twist
- A torsion of the limb which is influenced by the joint.
- two-dimensional scalar field
- A real bivariate function f defined over a subset of points D in the Euclidean plane.

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