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Project Settings - Wireframe Linking Control default settings for how strings are linked to form volumes |
Project Settings: Wireframe Linking
To access this dialog:
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In the Project Settings dialog, select the Wireframe Linking tab.
This tab is used to configure string-linking settings for your application.
The settings defined in this tab will become the system defaults for all subsequent wireframe linking operations that utilize those settings. In some cases, a 'command-scope' setting is available for a particular command, in which case the system defaults defined here will be temporarily overridden. For example, the 3D Solid linking method options shown at the bottom of this dialog will be shown, by default, on opening the Link Multiple Strings dialog. This dialog, however, also contains the same linking method options as this Wireframe Linking Settings dialog. Altering the default settings in the former will be used in preference to the system defaults defined in the latter - and the system defaults will be shown the next time the former is opened.
Field Details:
Linking Method: define the type of algorithm used to link string data:
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3D Solid: selecting this enforces a proprietary linking algorithm, and the results may be the same or different from the other linking methods, depending on different string layouts. The 3D Solid approach is particularly adept at overcoming the problems associated with bifurcated wireframe generation (see Trouser Leg Problem), and relies on either temporary (i.e. one operation) settings made via the Link Multiple Strings dialog to link sequential sets of closed strings to create a wireframe volume, or default values as defined in the 3D Solid Options section of this Wireframe Linking Settings dialog (see below).
Find out more about the algorithm behind the 3D Solid linking method... -
Minimum surface area: select minimum surface area as the string linking criteria. If toggled on, the resulting triangulation between selected strings will have the minimum wireframe surface area.
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Equi-angular shape: selects equi-angular shape as the string linking criteria. If toggled on, the resulting triangulation between selected strings will generate triangles where the preferred shape is equi-angular.
One measure of the shape of the triangle is the radius of the circumcircle fitted through the three vertices of the triangle. If the three points on the two strings selected to form a triangle minimise the circumcircle radius, this will generate a well shaped triangle. If the three edges were of equal length, the triangle would be an equilateral, and if two edges are of equal length then an isosceles triangle is formed with equal angles at the base of the triangle. If the optimal triangulation minimises the sum of the circumcircle radii of the triangles formed, then the preferred shape will be equi-angular. -
Proportional length: selects proportional length as the string linking criteria. If toggled on, the resulting triangulation between selected strings will generate triangles where the triangle edges are similar proportional distances along the two strings.
This criteria works best where the shapes of the two strings are similar. If the shape of the strings is dissimilar, then to get best results tag strings should be used to link together those string sections that are similar. The starting edge for the triangulation is determined either by a user defined tag string, or selected by the system using the closest pair of points on the two strings to be linked. The triangles are formed to best maintain their proportional position along the two strings.
If multiple tag strings are supplied, then the proportional position is defined between adjacent pairs of tag strings. For any pair of strings this method can only generate one link. If this criteria is selected and the toggle linking-method-switch is set on for optimal linking, then the equiangular shape method (link-radii-method switch) will be used.
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Although not set as the default string linking criteria, it will always be the fastest because no Optimization is involved. Where the shapes are similar this method can often produce the best link, particularly if tag strings are used judiciously. If string shapes are not similar then the other criteria (equi-angular shape, minimum surface area) work more effectively. |
String Linking Control: determine the way in which the method selected above is applied:
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Optimal linking: Toggle between optimal and sub-optimal (fast) linking methods. If turned on, when linking strings the wireframe will be created optimally with the best surface being selected from those that satisfy the linking criterion. If turned off the linking will be done with tag strings - either user supplied, or if none exist then the closest pair of points on the two strings after translation to a common centre of gravity will form an implicit tag string. Each pair of tag strings is linked independently. The speed advantage of the sup-optimal increases with an increasing number of string points. If the sub-optimal method fails then linking will default to the optimal method.
The Optimal linking option does not apply to the 3D Solid Linking method, and will be disabled if that method has been chosen. -
Link crossover checking: Toggle crossover checking on or off for string linking. If the crossover toggle is on then any link that would contain crossovers is automatically rejected.
Crossover checking will increase the processing time, especially where the strings have a large number of points. For regular string shapes the user may elect to set crossover checking off, but a wireframe intersection check is still recommended.
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End link multiple strings: select this check box to 'close' the ends of volumes generated by a string linking operation.
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Use tag strings: toggle the use of tag strings on or off for string linking. Tag strings are supplied by the user to provide additional control on string linking. This toggle controls whether the tag strings should be ignored when creating the link. The tag strings that may be required for sub-optimal linking to achieve the required shape and avoid crossovers may be unnecessary for optimal linking.
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Wireframe attributes from strings: toggle the source of wireframe attributes from strings or user. During string linking attributes can be taken from the attributes associated with the string, or alternatively from the values entered in the attribute panel with the new-wireframe, or new-wireframe-surface commands.
3D Solid Options: these fields are used to denote the default settings for the link-multiple-strings command, and the initial values shown in theLink Multiple Stringsdialog:
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Collate by distance: If this option is selected, the Collate by distance value specifies the maximum distance between strings for them to be considered on the same ‘level’. This state can also be toggled using the link-3dsolid-collate-switch command.
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Use current view plane: selecting this check box will attempt to sort the selected strings into groups according to their depth in current view coordinates. It is normally sufficient to leave this check box cleared, in which case, the 3D Solid algorithm will sort strings using its own criteria. This state can also be toggled using the link-3dsolid-view-plane-switch command.
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Align strings: select to create automatic ‘virtual’ tag lines, which control how the strings are linked together. This state can also be toggled using the link-3dsolid-align-switch command.
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Uniform Interpolation: Uniform Interpolation applies a unit length parameterization to the string segments between tag strings. That is, the vertices from one string are imprinted onto the other (vice versa) as if one cut each string, stretched both out to the same length, imprinted temporary vertices and formed connections; finally restoring the original string shapes. The wireframe is generated using both the temporary and original string vertices.. This state can also be toggled using the link-3dsolid-interp-switch command.
