Meatball function size scale problem

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Permalink Reply by David Rutten on February 8, 2013 at 11:42am

Metaballs, not meatballs. 

I can't really work out what the image you posted is showing. Metaballs have two important numbers that you must understand before you can use them effectively. One is the sampling density or 'Accuracy'. I do not have the math skills to write an analytic metaball solver so instead what I do is take small steps while tracing along the metaball curve boundary. This size of the steps can be adjusted. Very small steps result in a high accuracy outline but they also require more computation time.

The second number (Threshold) is to do with the shape of each metaball outline. If you want outlines that are close to the seed points then you need to pick a high threshold. Lower thresholds (but never zero or less as that would result in infinitely large metaballs) give you outlines that are further away from the seed points.

If you want to use Metaballs as part of a design project (architectural or otherwise), it's probably a good idea to understand how they work from a mathematical and algorithmical point of view.

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David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Simon on February 8, 2013 at 12:39pm

The problem I am having is that the points are so far apart, the metaball function will not connect them together even with a very low threshold value of 0.001 which is the lowest i can input. At the moment I am trying to create a definition at a small scale which I will scale up when it is finished. But it would be more conveinent to be able to have the points further apart and then build the definition at the correct size.

I also have a request could you make a rectilinear metaball component. Which works similar to the way the grouping box function works when you group components on the canvas. 

Also do you know the Soho complex in Beijing designed by Zaha Hadid I think it was designed by Patrick Schumaker using the metaball function, the really height of paramterically driven form. Everything in the project could be prescribed by a few sliders and values. The way the bridges where created using different threshold values at different heights. Very cool images from the early design development but a bit of a monster in real life.

Permalink Reply by David Rutten on February 8, 2013 at 6:17pm

You should be able to use a lower value than 0.001. I can specify 1e-10 without problems, just be sure to also enter a large A value so it doesn't take forever tracing out a kilometer long curve in 1 mm steps.

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David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Hannes Löschke on February 9, 2013 at 6:50am

Do you have any reference that Galaxy Soho was designed with metaballs? IMHO the connections are too small vs. the bodies to be done with a simple metaball.

Permalink Reply by Vicente Soler on February 9, 2013 at 1:34pm

Someone asked me how to model this. I did it using subdivs (Catmull-Clark) and it looked almost exactly the same.

Permalink Reply by Benjamin Felbrich on February 8, 2013 at 11:49am

"meatball" :D awesome...