Contours > Detect Contours is the automatic detection of relatively flat regions that lie between region separators, manual adjustment of region separators, and the placement of yellow (extendable) or orange (unextendable) contour lines within those region separators.
Use Detect Contours or Contours > Detect Curvature, but not both.
|
|
|
|
Red region separators (the result of the Detect Regions button) indicate high-curvature portions of the object and separate the relatively flat regions that are brightly colored. |
Orange contour lines (the result of the Extract button) that will serve as panel demarcation lines. |
|
|
|
|
Orange (unextendable) contour lines that represent sharp edges, plus yellow (extendable) contour lines that represent curvatures on the object. This is the result of the Extract button with the Detect Extension Contours checkbox. |
In a later step (Patches > Subdivide/Extend Contours), the yellow (extendable) contour lines can generate special “contour patches” that lie on the red region separators. Ultimately, contour patches allow the NURBS parameters to be specified separately in the flat and non-flat areas, which is beneficial for some objects. |
Contour lines generated by this function are of two varieties:
A yellow contour line can be “extended” (by Patches > Subdivide / Extend Contours) and thus represents a higher-curvature portion of the object.
An orange contour line cannot be “extended” and therefore represents a relatively sharp edge (a joint between two low-curvature portions) on the object.
The controls are:
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.
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).
Minimum Area (units^2) decimal field - specifies the smallest allowable size of any relatively flat region that will exist on the object after regions and region separators are detected. Reducing this size causes additional regions and region separators to be generated.
Compute Regions button - Press this to detect region separators and flat regions 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.
Contours 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.
Detect Extension Contours checkbox and Sensitivity decimal field - specifies whether to generate both orange (unextendable) and yellow (extendable) contour lines, and controls the threshold of curvature that yields those two varieties. When Detect Extension Contours is not checked (the default), all contour lines will be orange (unextendable). When Detect Extension Contours is checked, the Sensitivity field (0 to 100) becomes active. High Sensitivity generates more yellow contour lines and fewer orange contour lines.
Extract button - overlays the region separators with yellow and/or orange contour lines.
Contract button - removes a contour line (yellow or 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 contour line. The clicked line disappears and the endpoints become one. This process simplifies the contour patches that will be created by subsequent use of Patches > Subdivide/Extend Contours.
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.
Contours 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 regions and contour lines. The dropdown specifies what the arrow buttons apply to:
all Regions of the object - Use the arrow buttons to cycle through the set of relatively flat regions. If you see an imperfect one, click the Remove button to delete the Contour Lines and use the Editing group of controls to re-draw that region.
all Contours (all contour lines) of the object (sorted from shortest to longest) - Use the arrow buttons to cycle through the Contour Lines and use the Contract button above to remove small ones as necessary.
Problem Regions of the object - Use the arrow buttons to cycle through the flat regions that the software considers to be problematic. To correct a problematic region, click the Remove button to delete the Contour Lines and use the Editing group of controls to re-draw that region.
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.
Check Path Intersections checkbox (The state of this checkbox is shared with checkboxes of the same name in Contours > Detect Contours, Patches > Construct Patches, Contours > Subdivide/Extend, Patches > Shuffle > Panels, and the Check Geometry checkbox of Grids > Construct Grids) - specifies whether to advise the user, upon completion of this and related functions, whether certain imperfections should be fixed by using Patches > Repair Patches.
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.
The typical usage of this dialog is:
Use the Regions group to detect flat regions and region separators.
Use the Editing group to adjust the width of region separators, especially if a) a separator will be given an extendable (yellow) contour line and you want to control the eventual width of the contour patch, or b) if you want to guarantee the position of a yellow or orange line.
Use the Contours group to overlay the region separators with orange and yellow contour lines. If necessary, Remove the contour lines and return to Step 2.
Go to Patches > Subdivide/Extend Contours.
