Wednesday, March 13, 2013

Smoothing the outlines in Board Off

I've just made a minor change to Board Off to smooth the outlines. If you used BoardOff you may have seen that where the different sections (mid, mezz, corner, tip) join there is occasionally a small kink in the outline. This is the reason that the 'gradient ants' where introduced into the Draft window as they show the slope of the outline either side of where the sections join. The goal was then to adjust your parameters until the 3 Ants merged into one or close enough.

This was a short coming of the cubic splines used to draw the outline in that the way I'd implemented it it did not enforce and smoothness conditions at these kinks. I've made an adjustment to it so that for the corner-mezz, mezz-mid joins a continuity condition is in force and so there are no longer any kinks there. It wasn't possible to do it for the tip-corner join because the tips are so steep that the spline needed to approximate it has trouble turning the often small radius corners without causing the line to start going wild (oscillating). Also, for inverted tips its desirable to be able to have a sharp corner.

I've also applied this to the rocker and concave lines so that the kinks ( detected in the rocker and concave by the 'curvature' chart being discontinuous. They are now all smooth and much easier to work with.

The update did require some of the outlines to be modified as the continuity conditions to force a change in the shape of the outline in some cases. So you may need to check your own designs to make sure they haven't been affected.

Any questions, just post here and I'll endeavour to get back as soon as possible.


P.S I saved the new version over the old version 16. When you download it will say v17 even though the link says v16.

PSS Added the Naish rocker description I posted about earlier. I used equal length section ( 1/3 of the half length each). As I looked at the numbers it returned it became pretty clear that Naish is not using equal length sections. If they were then all numbers would need to be increasing otherwise the board would have and flat spot in the rocker. They must has different lengths. For my purposes the equal space ones are still useful as a shorthand way to describe it and compare others designed in board off.

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