geodesic lines in gridshell- problem

Hi,

I tried to make my first gridshell in grasshopper. I do not know why the geodesic lines are so weird. They should join points from the first and the last curve but they have strange shapes. Could someone look at it and help me? I will be gratefull.

Iwona

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Permalink Reply by Hannes Löschke on November 8, 2013 at 10:49am

I'm not sure, what you would expect them to look like... maybe you could post sketch or screenshot?

Here's what I think might trouble you: not every endpoint of the does precisely coincide with the original top or bottom curve.

This is perfectly normal. The geodesics are curves on a surface, you built from 10 sections along your curves. Loft will interpolate between those sections. The surface will match the curves at the sections, but not in between.

Now you take 20 points along top and bottom and calculate geodesics. Start end end will match the curve where there was a section for the loft. In between the geodesic wil start/end at the closest point ON the surface, not at the point you input.

Match number of geodesics with number of sections for the loft and everything should be fine.

Permalink Reply by Iwona D on November 8, 2013 at 3:58pm

Hi Hannes,

thank you for reply,

I made the printscreen of what is troubling me: I shifted the points with offset 1 and showed the numbers of points, in order to explain more precisely:

when I look at this grid - I don't know what is happening between points "0" and "5" the curves look like splains. The rest curves which connect points 6,7,8,...16 looks fine.

I understand the geodesic line as the shortest curve on a surface. I cannot find a mistake in what I did in grasshopper - why do the lines looking like splains appear?

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Permalink Reply by Hannes Löschke on November 8, 2013 at 4:04pm

Looks like this is specific to your machine. Here's what your definition looks like on my PC.

What's your Rhino and Grasshopper verison?

Permalink Reply by Iwona D on November 8, 2013 at 4:21pm

oh, your version is perfect!

I have Rhino 4.0 SR8 and I installed grasshopper grasshopper_wip_20120928,

something must be wrong with display in my computer..

Permalink Reply by Hannes Löschke on November 8, 2013 at 5:53pm

I'm running Rhino 5 (beta updates) and Grasshopper 0.9.0064.

Try to bake it. If the lines come out as you see them in the GH preview, it's a bug and you will probably have to update od find anopthe way to get your geodesics. If the baked geometry is ok, just ignore the strange preview.

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