geom/doc/salome/gui/GEOM/input/shape_processing_operation.doc

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\page shape_processing_operation_page Shape Processing

\n To produce a <b>Shape Processing</b> operation in the <b>Main Menu</b> 
   select <b>Repair - > Shape Processing</b>.
\n This operation processes one or more shapes using various operators.

\n The \b Result will be a \b GEOM.GEOM_Object.

\n <b>TUI Command:</b> <em>geompy.ProcessShape(Shape, Operators,
Parameters, Values),</em> where \em Shape is a processed shape, \em Operators
is a list of operators ("FixShape", "SplitClosedFaces", etc.),
\em Parameters is a list of parameters ("FixShape.Tolerance3d",
etc), \em Values is a list of values of parameters placed in the same
order as in the list of Parameters.

\note <b>Shape Processing</b> is useful not only on invalid shapes,
      but also on the shapes, that are classified as valid by
      the <b>Check</b> functionality. Use it, if an operation (for
      example, <b>Partition</b>) fails.
      Example of usage:
      <ol>
      <li>Try to partition objects obj1 and obj2.</li>
      <li>Partition fails.</li>
      <li>Perform Shape Processing on objects obj1 and obj2.</li>
      <li>Try to partition them again.</li>
      </ol>
      See also \ref tui_limit_tolerance "TUI example".

\n In this dialog box you can select the object that you need to
process, define its name and operators applied to it during
processing.

\image html repair1.png

<b>Operators and Parameters</b> (TUI names are given in brackets):

<ul>
<li><b>Fix Shape</b> (FixShape) - corrects invalid shapes.</li>
<ul>
<li><b>3D Tolerance</b> (FixShape.Tolerance3d) - work tolerance for
detection of the problems and correction of them.</li>
<li><b>Max 3D Tolerance</b> (FixShape.MaxTolerance3d)  - maximal
possible tolerance of the shape after correction.</li>
</ul>
<li><b>Fix Face Size</b> (FixFaceSize) - removes small faces, such as
spots and strips.</li>
<ul>
<li><b>Tolerance</b> (FixFaceSize.Tolerance) - defines minimum
possible face size.</li>
</ul>
<li><b>Drop Small Edges</b> (DropSmallEdges) - removes edges, which
merge with neighboring edges.</li>
<ul>
<li><b>3D Tolerance</b> (DropSmallEdges.Tolerance3d) - defines minimum
possible distance between two parallel edges.</li>
</ul>
<li><b>Drop Small Solids</b> (DropSmallSolids) - removes small
  solids or merges them with neighboring ones.</li>
<ul>
<li><b>Width factor tol.</b> (DropSmallSolids.WidthFactorThreshold) -
  defines the maximum value of <em>2V/S</em> of a solid, which is
  considered small, where \a V is the volume and \a S is the surface area of
  the solid.</li>
<li><b>Volume tol.</b> (DropSmallSolids.VolumeThreshold) - defines
  the maximum volume of a solid, which is considered small.</li>
<li><b>To merge solids</b> (DropSmallSolids.MergeSolids) - if
  activated, small solids are removed, else small solids are merged to
  adjacent non-small solids or left untouched if they cannot be merged.
</li>
</ul>
If the both tolerances are activated a solid is considered small if
it meets both criteria.
<li><b>Split Angle</b> (SplitAngle) - splits faces based on conical
surfaces, surfaces of revolution and cylindrical surfaces in segments
using a certain angle.</li>
<ul>
<li><b>Angle</b> (SplitAngle.Angle) - the central angle of the
resulting segments (i.e. we obtain two segments if Angle=180, four if
Angle=90, etc).</li>
<li><b>Max. Tolerance</b> (SplitAngle.MaxTolerance) - maximum possible
tolerance among the resulting segments.</li>
</ul>
<li><b>Split Closed Faces</b> (SplitClosedFaces) - splits closed faces
in segments. The number of segments depends on the number of splitting
points.</li>
<ul>
<li><b>Number of splitting points</b> (SplitClosedFaces.NbSplitPoints) - the number of splitting points.</li>
</ul>
<li><b>Split Continuity</b> (SplitContinuity) - splits shapes to
reduce continuities of curves and surfaces.</li>
<ul>
<li><b>3D Tolerance</b> (SplitContinuity.Tolerance3d) - 3D tolerance for correction of geometry.</li>
<li><b>Surface Continuity</b> (SplitContinuity.SurfaceContinuity) - required continuity for surfaces.</li>
<li><b>Curve Continuity</b> (SplitContinuity.CurveContinuity) - required continuity for curves.</li>
</ul>
\n This and the previous parameters can take the following values:
\par
<b>Parametric Continuity</b>
\n \b C0 (Positional Continuity): curves are joined (the end positions
of curves or surfaces are coincidental. The curves or surfaces may
still meet at an angle, giving rise to a sharp corner or edge).
\n \b C1 (Tangential Continuity): first derivatives are equal (the end
vectors of curves or surfaces are parallel, ruling out sharp edges).
\n \b C2 (Curvature Continuity): first and second derivatives are
equal (the end vectors of curves or surfaces are of the same
magnitude).
\n \b CN N-th derivatives are equal (both the direction and the
magnitude of the Nth derivatives of curves or surfaces (d/du C(u)) are
the same at junction.
\par
<b>Geometric Continuity</b>
\n \b G1: first derivatives are proportional at junction.
\n The curve tangents thus have the same direction, but not necessarily
the same magnitude. i.e., C1'(1) = (a,b,c) and C2'(0) = (k*a, k*b,
k*c).
\n \b G2: first and second derivatives are proportional at junction.
\n As the names imply, geometric continuity requires the geometry to
be continuous, while parametric continuity requires that the
underlying parameterization was continuous as well.
\n Parametric continuity of order n implies geometric continuity of
order n, but not vice-versa. 

<li><b>Bspline Restriction</b> (BsplineRestriction) - converts curves
and surfaces to Bsplines and processes them with the following
parameters:</li>
<ul>
<li><b>Surface Mode</b> (BSplineRestriction.SurfaceMode) -
approximation of surfaces if restriction is necessary.</li>
<li><b>3D Curve Mode</b> (BSplineRestriction.Curve3dMode) - conversion
of any 3D curve to BSpline and approximation.</li>
<li><b>2D Curve Mode</b> (BSplineRestriction.Curve2dMode) - conversion
of any 2D curve to BSpline and approximation.</li>
<li><b>3D Tolerance</b> (BSplineRestriction.Tolerance3d) - defines the
possibility of surfaces and 3D curves approximation with the specified
parameters.</li>
<li><b>2D Tolerance</b> (BSplineRestriction.Tolerance2d) - defines the
possibility of surfaces and 2D curves approximation with the specified
parameters.</li>
<li><b>Required Degree</b> (BSplineRestriction.RequiredDegree) -
required degree of the resulting BSplines.</li>
<li><b>Required number of segments</b>
(BSplineRestriction.RequiredNbSegments) - required maximum number of
segments of resultant BSplines.</li>
<li><b>3D Continuity</b> (BSplineRestriction.Continuity3d) -
continuity of the resulting surfaces and 3D curves.</li>
<li><b>2D Continuity</b> (BSplineRestriction.Continuity2d) -
continuity of the resulting 2D curves.</li>
</ul>
<li><b>To Bezier</b> (ToBezier) - converts curves and surfaces of any
type to Bezier curves and surfaces.</li>
<ul>
<li><b>Surface Mode</b> (ToBezier.SurfaceMode) - if checked in, allows
conversion of surfaces.</li>
<li><b>3D Curve Mode</b> (ToBezier.Curve3dMode) - if checked in,
allows conversion of 3D curves.</li>
<li><b>2D Curve Mode</b> (ToBezier.Curve2dMode) - if checked in,
allows conversion of 2D curves.</li>
<li><b>Max Tolerance</b> (ToBezier.MaxTolerance) - defines tolerance
for detection and correction of problems.</li>
</ul>
<li><b>Same Parameter</b> (SameParameter) - fixes edges of 2D and 3D
curves not having the same parameter.</li>
<ul>
<li><b>3D Tolerance</b> (SameParameter.Tolerance3d) - defines tolerance for fixing of edges.</li>
</ul>
</ul>

\n <b>Example:</b>

\image html image154.png
<center><em>Shape before applying Shape Processing (FixShape
operator). View # 1.</em></center>

\image html image156.png
<center><em>Shape before applying Shape Processing (FixShape
operator). View # 2.</em></center>

\image html image160.png
<center><em>The same shape after applying Shape
Processing.</em></center>

Our <b>TUI Scripts</b> provide you with useful examples of the use of
\ref tui_shape_processing "Repairing Operations".

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