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3MFConsortium / spec_volumetric

The 3MF volumetric extension specification
BSD 2-Clause "Simplified" License
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explain narrow band concept #44

Open martinweismann opened 2 years ago

martinweismann commented 2 years ago

2.1.1 File Formats

A typical approach to store this levelset information is to encode the signed distance field of the boundary of the object in this channel, or to limit the encoding to a narrow region around the boundary of the object.

Referencing a narrow band here is misleading without giving more context. Why is the narrow band mentioned here? One may exploit the "narrow band" concept for better compression by scaling the scalar function so that it will be clamped inside narrow band, thus most of the pixels will be 0/255 or 0/65535.

Extracted from https://github.com/3MFConsortium/spec_volumetric/issues/42

martinweismann commented 2 years ago

Even better: Add three images for how to encode levelset information: signed distance, narrow band SDF, high resolution binary/black and white image.

martinweismann commented 2 years ago

Fixed in https://github.com/3MFConsortium/spec_volumetric/pull/52

martinweismann commented 2 years ago

Let's explain how this is achieved in the png (truncating values). and that this gives much better compression.