Three-dimensional wireframes

On this level, no entities of type S0LID M0DEL and SURFACE are available. Also, entities which can occur only within the scope of these entities are not available. 

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For three-dimensional wireframe models intersection points between the curves of the model and test planes are to be used. 

This relation expresses the fact that the points referenced by the results attribute have been produced in the sending CAD system by intersecting the three-dimensional wireframe model referenced by the geometry attribute with the test plane. The CAD system user in the receiving environment may use this information to test the accuracy of the transmitted geometry by repeating this intersection operation. 

Figure 4.11. Graphic representations of protein 3D structure. Three-dimensional graphics of hen s egg-white lysozyme as visualized with RasMol (first and second rows, ILYZ.pdb) and Cn3D (third row, ILYZ.val) are shown from left to right (color type) in wireframe (atom), spacefill (atom), dots (residue), backbone (residue), ribbons (secondary structure), strands (secondary structure), secondary structure (secondary structure), ball-and-stick (residue), and tubular (domain) representations.

The new set of varied DF found in the previous section can be studied in the same way as the well-known eDF maps are represented since the first plots used in Quantum Chemistry [53a)]. Here an alternative point of view, similar as the one used by Mezey [9a)], will be chosen. Three-dimensional maps of isodensity surfaces can be generated with available computational techniques [84]. This corresponds to follow several steps, some of them so trivial that appear to be irrelevant in a study as the present. The representation process starts with the evaluation of DF grids, enveloping the molecular co-ordinates, which can origin wireframe structures related with the isodensity values. After that, they can be rendered and rotated in space as virtual objects, until some adequate point of view is found. Finally, the chosen object snapshot can be manipulated, represented on a screen and, if necessary, printed into a paper surface. The processing detail, the computational techniques and the required programs and data are briefly commented in Appendix E. All the necessary items are available to the interested reader and permit to generate surfaces of his own [93-96]. 

Figure 5.1 Common representations of the three-dimensional structures of proteins Three-dimensional graphics of hen s egg-white lysozyme as visualized with RasMol (first row, ILYZ.pdb) are displayed in wireframe (residue type), spacefill (atom type) and backbone (structure type). The Cj, mainchain with side chain residues is displayed with KineMage (second raw left). The secondary structure representations (a helices and P-sheets) are visualized with KineMage (lLYZ.kin) in ribbons and arrows (second raw center), and Cn3D (ILYZ.cnS) in cylinders and arrows (second raw right).

Figure 2.28 (a) A three-dimensional CAD drawing of a rubber duck and (b) the associated convex hull, given in a wireframe representation. (See color plate section for the color representation of this figure.)... 

For example, three-dimensional wire-frame models can be constructed to help visualize the product and serve as a framework for other modeling programs. (More details on wire frame and other modeling techniques are presented later in this chapter.) These wireframe models, which are constructed in three dimensions, can normally be viewed in orthographic, isometric, or perspective views, often at the same time. Changing one view alters all the other ones. Wire frames are easily modified, and many design variations can be constructed in a relatively short time. 

The GEOMETRIC MODEL is a class representing entities according to the geometric modeling techniques WIREFRAME MODEL (two-dimensional and three-dimensional) SURFACE MODEL, and SOLID MODEL. 

The surface curve is a single scoped entity which contains in its scope the complete data structure that defines the curve geometry, hence, in wireframe models the surface-curve behaves as a single three-dimensional curve entity (see "Points and curves" on page 56 and "Geometry on surfaces"). The curve attribute refers to the top of that data structure. The surface entities which are referred from within the curve on surface entities may lie within the scope of the same surface-curve or outside. 

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