Live data from Hacker News

Computational Hydrographic Printing [video]

youtube.com

1–10 of 33 posts

Re: Computational Hydrographic Printing [video]

#4
Very cool. Anyone know how a sphere (the globe at the end) was printed in a single immersion? Based on what I saw in the video, it seems like it would have to be a different process involving rotating the sphere as it was dipped, rather than the linear motion used for the other objects.

Re: Computational Hydrographic Printing [video]

#5
post #4

Very cool. Anyone know how a sphere (the globe at the end) was printed in a single immersion? Based on what I saw in the video, it seems like it would have to be a different process involving rotating the sphere as it was dipped, rather than the linear motion used for the other objects.

Was the sphere inside the globe framework when it was printed? If it was merely a sphere being immersed, then perhaps a polar projection map would be able to cover all of it.

Re: Computational Hydrographic Printing [video]

#6
post #4

Very cool. Anyone know how a sphere (the globe at the end) was printed in a single immersion? Based on what I saw in the video, it seems like it would have to be a different process involving rotating the sphere as it was dipped, rather than the linear motion used for the other objects.

From the paper[1], it sounds like the same linear motion with the film wrapping around to the top:

    > The sphere is dipped with
    > its north pole pointing downward. The maximum error on the
    > northern hemisphere is within 2mm. However, near its south pole
    > the error is much larger (about 5mm). This is because after the
    > water surface passes the sphere’s equator, the film gets stretched
    > largely, and near the south pole the relative angle between the
    > water surface and the object surface approaches to 180◦, leading
    > to an ill-posed boundary condition for our simulation (recall
    > Equation (1), when θ ≈ 180◦).
You can see the potential for a similar wraparound even on e.g. the mask dips.

[1] http://www.kunzhou.net/2015/hydrographics.pdf

Re: Computational Hydrographic Printing [video]

#7
post #4

Very cool. Anyone know how a sphere (the globe at the end) was printed in a single immersion? Based on what I saw in the video, it seems like it would have to be a different process involving rotating the sphere as it was dipped, rather than the linear motion used for the other objects.

Don't believe so, a single projection with antarctica on the outside and the north pole at the centre would likely work just fine - and they showed it top-down.

Re: Computational Hydrographic Printing [video]

#9
What kind of surface doesn't fit this computational model? The elephant one for example, how to map the region which is occluded by the elephant's nose to the PVA surface? Anyway, really nice work. Looking forward to reading the paper and learn more!
Post reply on HN