PDQ criteria

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PDQ criteria by Mind Map: PDQ criteria

1. Detection of Faulty data

1.1. Bad shape

1.1.1. Self-intersection topology_related_to_self_intersecting_geometry self_intersecting_geometry Always erroneous in any application Informal rule in Part 42

1.1.2. Small segment/patch nearly degenerate segment or patch or boundary indistinct curve/surface knots nearly_degenerate_surface_boundary short_length_curve_segment small_area_surface_patch narrow_surface_patch nearly_degenerate_surface_patch extreme_patch_width_variation Maybe problematic for some systems, e.g. projecting curve onto the surface. Relatively narrow patch.

1.1.3. Bad condition of curve/surface normal Normal value zero_surface_normal surface_with_small_curvature_radius curve_with_small_curvature_radius Basically bad shape, but it's difficult to set threshold, Because it is not logically linked to system point coincident tolerance. -> That decreases severity of these criteria. Change of direction steep_geometry_ transition_across_edge abrupt_change_of_ surface_normal

1.2. Redundant data

1.2.1. multiply_defined_*

1.2.2. overlapping_*

1.2.3. overcomplex_*

2. Interpretation of explicit condition

2.1. Violation of mathematical representation

2.1.1. erroneous_data

2.1.2. occurrence possibility is low

2.1.3. Severity is extremely high when occurred.

2.1.4. It's very rare to use these for data from stable systems

2.1.5. Some criteria are used for cleaning up very dirty data. In this case, experiment is needed to specify criteria to be used.

2.2. Specification of CAD

2.2.1. Restriction of mathematical representation inapt_topology excessively_high_degree_curve/surface discontinuous_geometry These criteria are to be automatically handled by data translator if possible, or checked just before translation.

2.2.2. Basic accuracy of CAD nearly_degenerate_geometry geometric_gap_in_topology small_volume_solid and entirely_narrow_solid Severity is high when occurred Why not included in CAD specification dependent? -> criteria in "CAD specification dependent" arena is the ones to be handled in general data translator. And many CAD don't use fixed value. It is not easy, and sometimes undesirable to handle these criteria in data translator

2.3. Use case

2.3.1. non_smooth_geometry_transition_across_edge

2.3.2. inapt_topology