3D Fairing of Curves

[miano]

Is there some tool out there that will do 3D fairing of curves.

If i start with a grid of points and draw vertical and horizontal curves through them, I would like to be able to fair the curves such that the horizontal and vertial curves continue to intersect.

Or restated, I would like to fair the points such that, if i start with points in line in the X and Y directions, that the poiints will move only in the Z direction to create smoother curves.

[scottd (Scott Davidson)]

Might want to show us a model, but I use Nudge a lot to fair curves.

Nudge options | Rhino 3-D modeling

Here is an older tutorial on fairing: https://www.flexicad.com/public/Uebung_Glaettung.pdf

[davidcockey]

@miano I assume you are interested in fairing a set of lines for a boat or ship, starting with a table of offsets for the point locations.

@miano

I would like to fair the points such that, if i start with points in line in the X and Y directions, that the poiints will move only in the Z direction to create smoother curves.

Record History on.
CurveThroughPts to create the curves through the points. I usually use Knots=Chord.
CurvatureGraph on for the curves.
Select and move the points as desired. I also usually use Nudge. The curves will automatically update to the new point locations.

[davidcockey]

My method for entering a table of offsets as points into Rhino: Table of Offsets into Rhino as 3D Points

My approach to fairing a set of hull lines is to create a “virtual half model” surface based on the table of offset points. The virtual half model is then adjusted/faired until I’m satisfied with the combination of the fairness and the deviation from table of offsets. A revised set of lines and offsets can be created from the virtual half model.

General approach to using a table of offsets:

Tool for 3d Fairing

@bigjimslade I assume you are describing fairing a set of boat/ship “lines” starting with a table of offsets. My approach is to first find the “typos”. I import the offset points and then create the curves using CurveThroughPt on the points for each waterline, buttock, sheer, rabbet, etc. I carefully look at the curves for the points which are obviously off, look at the corresponding offset, and usually can figure out that 1-7-6 should have been 1-6-6 or that 2-3-1 should have been 2-3-7 or sim…

3d Fairing of Table of Offsets

One approach: Create a set of edge curves. First create polylines around the boundary from the input points on the edges. Use FitCrv to obtain a NURBS curve from the polyline. The polyline is used as the input to FitCrv because “When the input to the FitCrv command is a polyline, the FitCrv command treats the polyline vertices as a list of points, and it tries to compute a curve that goes near the points but has a reasonable number of control points. The FitCrv command is meant for polylines wi…

Approach used to create the virtual half model:

Input from a table of offsets, is that possible?

Below is a brief description of the method I use for creating a hull surface from offsets using Rhino. Import the offsets into Rhino as coordinate triplets to create a set of points. Create curves the points using CurveThroughPts with Knots=Chord. If any curves have kinks, for instance where they cross a chine, create separate curves for each segment between kinks. Look for large, obvious errors in the point locations, correct those and generate corrected curves. I do not spend a lot o…

Modeling hulls with stems which smoothly transition into the keel"

Boat hulls with smoothly curve stems - how to model

Round bottom boat hulls frequently have stems which curve smoothly into the keel. A NURBS surface with four sides is not a simple fit to such a shape. [Curved Stem Lines 1] I know of three methods to model such a hull side using a single NURBS surface on each side. Each has advantages and disadvantages. A Rhino .3dm file with an example of each method is attached. BowCurve11.3dm (350.3 KB) The surfaces are very close to each other in shape. Note that the orange curves are isolines but do not …

[miano]

I asked again because I finally broke down and started to program my own.

My plan is to start with a spreadsheet of data. In a Macro I would define ranges that are

1. Fixed
2. “Curves” that are variable in Y/Z
3. “Curves that are "variable in Y

Those would define outlines and knuckles.

4. [Ranges] boarded by one of the above faired as surfaces.

Each of the above will invoke a macro that converts F-I-8 values in one table into decimal values in another table.