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Skill-Based Expert Systems in Robotics
Published in Spyros G. Tzafestas, Intelligent Robotic Systems, 2020
Careful observation of the preshaping phenomenon reveals facts that are essential for the design of the skill-based expert system for manipulator control. The hand preshaping form does not fit the details of the target contour. As the model for the hand preshaping serves the simplified target form. Experimental evidence shows that the number of hand preshaping forms is greatly reduced and is no larger than the number of geometric primitives, such as the ball, the parallelepiped, the cylinder, or the cone. All target shapes for which a geometric primitive serves as the circumscribed body are equivalent from the point of view of hand preshaping. The details of the target contour are taken care of only when the physical contact of the hand with the target is established. At that moment, the local hand controller takes over the job and adapts the fingers to the details of the target contour by a reflex act involving tactile sensors. In Figure 6 the hand preshaping for several characteristic targets is shown. It is highly interesting to realize that, for a given target shape, the resulting preshaping form is the same for all individuals.
Image-Based Lighting
Published in Francesco Banterle, Alessandro Artusi, Kurt Debattista, Alan Chalmers, Advanced High Dynamic Range Imaging, 2017
Francesco Banterle, Alessandro Artusi, Kurt Debattista, Alan Chalmers
EnvyDepth is based on an iterative select-and-annotate workflow supported by a sketch-based interface. For each edit, the user selects regions of the environment map that should be reconstructed using a sketch-based metaphor [304]. Two types of strokes are placed directly on the environment map, to indicate regions that should be included or excluded from the selection. Then, edit propagation [19] is used to compute a selection from these imprecise strokes. At this point, the user assigns a geometric primitive for each selection such as: planes, which can be horizontal or vertical, extrusions from the profile of a plane, domes, and distant illumination. EnvyDepth outputs a depth map from which virtual point light sources are generated and used for rendering images in a straightforward way; see Figure 7.15.
Algorithmic approaches to BIM modelling from reality
Published in Yusuf Arayici, John Counsell, Lamine Mahdjoubi, Gehan Nagy, Soheir Hawas, Khaled Dewidar, Heritage Building Information Modelling, 2017
Ebenhaeser Joubert, Yusuf Arayici
For a model to be considered parametric, the key building elements need to be defined and modelled with their relationships amongst one another. Further steps to achieve the above includes geometric primitive detection, point cloud clustering, shape fitting and classification.
The hip joint as an egg shape: a comprehensive study of femoral and acetabular morphologies
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Daniel Simões Lopes, Sara M. Pires, Carolina D. Barata, Vasco V. Mascarenhas, Joaquim A. Jorge
However, it is important to stress the hierarchical connection between all the shape primitives, in order to fully understand how the surface-fitting process is built. Considering the initial and simplest surface represented in (Figure 2), the sphere, it is possible to obtain the remaining surfaces through non-linear morphing operations, such as rescaling, exponentiation and asymmetrisation. The changes generated by these actions are easily identified on the resulting surface, being the higher level of squareness exhibited by surfaces such as superellipsoids, superovoids and tapered superellipsoids an example of the modifications introduced by variation in exponentiation. The orientation of the arrows composing the hierarchical graph (Figure 2) indicates which shape models constitute generalisations and which are particular cases within a given geometric primitive. For example, superovoids are a generalisation of superellipsoids and ovoids, whereas ellipsoids are a particular case of both superellipsoids and tapered ellipsoids.
An impulse response formulation for small-sample learning and control of additive manufacturing quality
Published in IISE Transactions, 2023
The input representation therefore entails the representation of individual layers and layer stackup. Borrowing geometric primitive concepts from computer graphics, we propose to use line segments, circular sectors, and corners as primitive shapes to construct individual layer boundaries or 2D shapes (Figure 3(a)). Notice that the three 2D shape primitives have curvatures of zero, constant, and infinity, respectively. Comparing to line segments on the grids in Figure 2(b), the choice of primitives will reduce computational load of approximation and assist in the interpretation of the deviation patterns. We therefore state the following accepted truth as the basis for the subsequent derivation:
An adaptive process of reverse engineering from point clouds to CAD models
Published in International Journal of Computer Integrated Manufacturing, 2020
The paper is organized as follows. Related work is summarized in Section 2. Geometric primitive shape fitting is presented in Section 3. The rule for alignment of primitive shapes is described in Section 4. The CAD object results and evaluations of the proposed method are presented in Section 5, and Section 6 concludes the proposed method and discusses future work.