Extract Curves

Curves > Extract Curves analyzes a point or polygon object’s geometry to detect areas of higher angularity, allows override of angularity detection, and draws orange “dependent curve” lines that trace the object’s angularity. In the Shape phase, those dependent curves will become constrained (red) patch-demarcation lines.

(The user dialog for this Curves > Extract Curves is similar to Contours > Detect Contours.)

• Regions group - controls the detection of high- and low-curvature portions of the object. Relatively flat regions will appear in bright colors like the countries on a map, and will become panels in a later step.

• Curvature Sensitivity decimal field - A higher value causes a higher number of distinct regions of relative flatness to be found.

• Minimum Area (units^2) decimal field - specifies the smallest allowable size of any relatively flat region that will exist on the object after colored regions and red region separators are detected. Reducing this size causes additional region separators and additional flat regions to be generated.

• Separator Sensitivity - decimal field (0.0 to 100.0, typically 60.0 to 95.0, default 80) - determines the relative width of the region separators. A higher value captures more of the fillet and creates a wider red separator.

If you expect to extract contour lines and then extend them to make contour patches, it is important that the region separators be wide enough to include all or most of the underlying fillet (thus avoiding a bump or seam next to the contour patch).

• Compute Regions button - Press this to detect regions and region separators based on the given parameters.

• Editing group - adjusts the automatically detected region separators.

• Remove Islands icon button - de-selects islands of selected polygons that are floating in a flat (brightly colored) region.

• Remove Small Regions button - removes tiny flat regions (groups of unselected polygons that are surrounded by selected polygons) by selecting them and thus joining them to a region separator.

• View Selected Only button - removes all flat regions except selected regions from the Viewing Area. Click this button, then click a point in a single flat region or click and drag the mouse to select two or more flat regions.

• View All button - restores the Viewing Area to include all flat regions of the object.

• Brush Size integer field - controls the size of the paintbrush that is used as a selection tool. Left-Drag the mouse to select more triangles into a region separator, or Ctrl-Left-Drag to de-select triangles from a region separator.

• Curves group - controls the placement of yellow (extendable) and orange (unextendable) contour lines into region separators. Extendable contours will yield contour patches; unextendable contours represent the joints between relatively flat portions of the object.

• Min Length decimal field - specifies the length of contour lines (orange or yellow) that will be automatically “Contracted” during the Extract process.

• Extract button - overlays the region separators with yellow and/or orange contour lines.

• Contract button - removes a contour line (orange) by joining its endpoints. This button is typically used to convert two three-degree vertices into one four-degree vertex. Press this button, then click a curve line. The clicked line disappears and the endpoints become one. This process simplifies the contour patches that will be created by subsequent use of Contours > Subdivide / Extend Contours [14-15].

• Remove button - removes all orange and purple contour lines from all region separators so that region separators can be further edited.

• Display group -

• Region Colors checkbox - whether to display the relatively flat regions in multiple bright colors like the countries on a map.

• Curves Only checkbox - (only after contour lines have been overlayed in the region separators by use of the Extract button) hides everything in the Viewing Area except the orange and yellow contour lines.

• Step Through dropdown with First, Previous, Next, and Last buttons - Allows methodical examination of all generated curve lines.

• Clip Plane checkbox - guarantees that the region being viewed will not be obscured in the Viewing Area by other elements of the object. This checkbox generates a cut-away view of the region of interest.

• OK button - saves the Shape object to the Model Manager and closes the dialog.

• Cancel button - terminates the dialog without saving changes to the object.