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  m powers

  9 years ago

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  Wow.

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  Jay Be

  9 years ago

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  I was always told by the engineers to measure from a datum point. Are these the actual manufacturing drawings or are the simply a guide for after market manufacturers?.

  Also the curve isn't Conic is curvature continuous maybe at 5 or 7 point or something, haven't worked in alias for years but from the looks of it thats what they're trying to show, in automotive I don't think you even bother marking up this curves as you hand the surface data straight to the manufacturer.

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  Anon Ihmos

  9 years ago

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  So, why did Apple go through all the trouble of marking down control points for a spline instead of just giving us the end points and rho value for a conic? It'd have cleaned up the drawing markedly.

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  • 

    Paolo Zago

    Anon Ihmos

    9 years ago

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    Those are probably not conics but splines or even better NURBS curves. You can repersent a correct conic curve with a rational bezier curve of degree 2 but you need higher degree to obtain good cuvature continuity and an aesthetically pleasing connection with the straight line. Also I suspect they just dimensioned  points on the curve measured at a regular interval, in a way that every interpolation you could build on them will have a desired error with respect to the actual curve used. It's a common practice in optical design for example.

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  • 

    Rob McCulloch

    Anon Ihmos

    9 years ago

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    I agree, it's very frustrating.

    Most of Apple's products that need cases have conic corners yet their drawings are all straight line splines when you zoom in.

    It makes getting a really good fit the first time a learning experience for sure!

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