Creating Curves from Scans

You can create curves from a scan or a set of scans, possibly with the defined tolerance, and with the least possible number of segments of the least possible order. Curve from Scans also proposes a dynamic definition of split points.

This task shows you how to:

Before you begin:
  • Scan modifications are not dynamic. Click Apply to take new parameter values into account.
  • The scans can be selected in the tree.

See About Constraints for Curve from Scan

Create a Curve

You can select one or several scans and create curves from them.

  1. From the Wireframe section of the action bar, click Curve from Scan .
  2. Select a scan.

    Multiselection is available.

    The scan is displayed in the Polyline+Point mode with the current graphic symbol.

    By default, the end points are fixed.

    Note: A split point has been automatically inserted. This insertion is controlled by the parameter Split Angle. Whenever the computed curve forms an angle greater than this value, the curve is split automatically into two curves. The split point is displayed and two curves are created.
  3. Optional: Modify the value of the split angle and click Apply.
  4. To create a curve by smoothing all the points between two split points, select Smoothing, and specify the parameters as required.
    1. Key-in a tolerance, that is the maximum distance between the final curve and the points.
    2. Key-in the maximum order of the curves to create, that is, the number of control points of those curves.
    3. Key-in the maximum number of segments between two cutting points.
    4. Click to verify that the tolerance is met.
      If the tolerance is met, the computed curve is displayed in white. Otherwise it is displayed in red.
    5. Click to verify the segmentation and the order of the curves.
    Curve from Scans tries to create curves with the defined tolerance, with the least possible number of segments of the least possible order:
    • Curve from Scans tries to create a curve with one segment of order 2.
    • If the tolerance is not reached, the order of the segment is increased up to the Max. Order value.
    • If the tolerance is not yet reached, the number of segments is increased, the segments having the least possible order. This order is increased to meet the tolerance, then the number of segments, and so on, until both the maximum order and the maximum number of segments are reached.
  5. To create a curve by interpolating the points of its support scan, select Interpolation.
  6. Click Apply.
    A temporary curve is displayed in white, indicating the tolerance is met.
  7. Optional: Press to display the curvature analysis.
  8. Release and click to display the maximum and the mean deviations (green callout below) and to display the order and the number of segments (black callout below).
    If the tolerance is kept, the maximum and minimum deviations are displayed in green. If the tolerance is not kept, they are displayed in red and the percentage of points that are out of the tolerance is also displayed.

Curve.x elements are created. The segmentation display is erased.

Manage Split Points and End Points

You can modify the split and end points.

  1. Pick a point on a scan.
    A split point is added at this location.
  2. Move a split point:
    1. Pick the split point you want to move.
    2. Press the Ctrl key and left-click the callout of the split point to drag the split point to the required scan point and drop it there.
  3. Set a constraint on a split point:

    By default, the constraint on a split point is Point, that is, passage.

    • Click the green callout to change it to Tangent. Click it again to revert to Point.
    • Right-click a split point and select the required menu item:
      • Remove point
      • Remove all points
      • Impose tangency
  4. Right-click an end point and select the appropriate action.

    • Remove point
    • Remove all points
    • Constrain this point
    • Impose tangency
    • Constrain on element
    • Edit tangent

    See About Constraints for Curve from Scan for more information.

  5. Select Constrain on element.

    Note: Unless Constrain on element is selected, the computed extremity of the curve is the scan extremity.

    • If the constraining element is a point, the curve extremity is that point.
    • If the constraining element is a curve, the computed curve extremity is the nearest extremity of the constraining curve.
    • If the constraining element is a plane, the curve extremity is the orthogonal projection of the scan extremity on to the plane.
    • If an extremity is constrained on an element, and if a tangency is imposed, the tangency direction is given by:
      • The tangent vector of the curve on the constraining curve extremity
      • Or the normal to the constraining plane.
  6. Right-click a callout and select Impose tangency, then Edit tangent to modify the tangent vector.

    Note: A tangency constraint at the extremities ensures that the two halves fit perfectly if you intend to reconstruct a part in two steps:
    • Reconstruction of the first half of the part
    • Recovery of the whole part by performing a symmetry.

    Only the tangency direction is taken into account. The norm is not.

    This option is available in Curve from Scan only.