
Computational Hydrographic Printing [video] - bpierre
https://www.youtube.com/watch?v=YlUhPrAqiY0
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function_seven
I was amazed until they got to the cat (about 3:00 in). At that point I was
blown away. The inside surfaces of the "outside" legs were also accounted for
in the mapping, and it was spot on.

This is seriously cool.

~~~
myth_buster
This is incredible but I'm assuming that the print and the objects are
painstakingly aligned as the immersion rod has no lateral movement.

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AnkhMorporkian
Sure seems like something that could be easily remedied in future iterations.
They've already figured out the hard part; alignment is a solved problem for
all intents and purposes.

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solidangle
If anyone is interested in the other papers that are presented at SIGGRAPH
2015, Ke-Sen Huang usually has a complete list with links to preprints and
videos. You can find the list for SIGGRAPH 2015 here:

[http://kesen.realtimerendering.com/sig2015.html](http://kesen.realtimerendering.com/sig2015.html)

My favorite paper this year is "The SGGX Microflake Distribution" by E. Heitz
et al. Sadly there aren't many papers on rendering this year.

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rndn
No technical paper preview trailer this year?

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j2kun
I am always jealous of how cool and flashy the work at SIGGRAPH is.

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agumonkey
The amazement never fades, every year brings its share of complex maths and
aesthetic sensations.

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henkboyd
I love how this is a complementary technology to 3D printing by the way of a
traditional printer. Simple. Effective. The biggest obstacle for widespread
adoption might be software, in other words a robust toolkit for designing
"wraps" of these imprints for your own 3D models.

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GhotiFish
Well I may just be suffering from the curse of knowledge, but I found blenders
texture paint system to be very good.

Once set, you can employ so many techniques with it to map images to a 3d
model.

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pcurve
Wow, multiple pass dipping was awesome. I wonder if there's some kind of 3d
painting machine that can compete with this.

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yzh
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!

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DanAndersen
The failure modes listed in the paper are models with a lot of concavities or
self-occlusions. Looking at the video, it looks like the elephant cup succeeds
because of surface tension properties of the water, which let the surface on
each side of the trunk "snap together" when the trunk begins to be completely
immersed. It's that wrapping or stretching that lets it be more than a simple
light projection, which would fail due to self-occlusion.

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yzh
Thanks. I found this in the paper too. Like you said, high concavity and
significant self-occlusion are two cases that are more likely to fail.

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agf
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.

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alepper
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](http://www.kunzhou.net/2015/hydrographics.pdf)

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KaiserPro
Interesting, This appears to be texture re-projection. The novel bit is
accounting for the elasticity of the PVA film.

For those of you who aren't in 3d/VFX:

UV mapping is essentially this process. Most 3d models you'll see, the colour
you see started out as a 2d image

[http://wiki.blender.org/index.php/Doc:2.4/Manual/Textures/Ma...](http://wiki.blender.org/index.php/Doc:2.4/Manual/Textures/Mapping/UV/Unwrapping)
has a good example of how texture are extracted from a 3d model.

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luismarques
Do you know what those cloverleaf shaped metal beams are called, and how you
can learn more about building hardware prototypes with those kinds of
products?

I know very little about mechanical engineering and hardware prototyping, but
I saw those metal thingies about a year ago in a DYI tinkerer community (it
was used in a DYI 3D printer), and I have been wondering about that topic ever
since.

~~~
JeremyHerrman
Those metal beams are called aluminum extrusions and are sometimes referred to
by the brand name "80/20".

They're super fun and useful in prototyping - kind of like an erector set for
adults.

~~~
luismarques
Thanks! What other items often go together with these aluminum extrusions? Is
there a place or a book to learn about this topic, or is it something that
people only learn through experimentation and mimicking?

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olympus
In addition to the 8020 beams already mentioned, there are also MakerBeam
([http://www.makerbeam.eu/](http://www.makerbeam.eu/)) and OpenBeam
([http://www.openbeamusa.com/](http://www.openbeamusa.com/)).

Primarily they are used for building structures quickly and easily - a saw and
a wrench are the only tools you need. The standardized brackets for each beam
type allow you to make 90 and 45 degree angles.

But they are often used for more than just framing. The 3D printing community
has embraced extrusions because you can also use them as bearing surfaces,
mount motors and servos, limit switches, etc. Basically anything that has a
hole big enough for a machine screw can be mounted to a beam either directly
or through an easily made mount (usually to get the angle that you want - all
it takes is some sheet metal).

The quickest way to learn is to look at examples. The OpenBeam website has
lots of examples. The system is so simple that you can understand exactly what
is going on just by seeing a picture.

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ww520
Wow, this is very cool. They invented a new method for printing taking
advantage of the fluid nature of liquid to get to every surface of a 3-D
object.

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smosher_
FYI hydrographic printing isn't new... nor is the computational part to be
honest. I assume both of these techniques have been used together before, but
what we are seeing here is both: very well done, and: using off-the-shelf
components.

Bonus the-future-is-now moment: "3D vision systems" are "off-the-shelf
components".

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WhitneyLand
What do you mean the computational part isn't new, who has done it before?

I would guess the part that would be commonly done is the texture mapping and
the print out of some kind of simple projection

It looks like they have added, crucially, the math to account for the topology
of the dipping process.

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smosher_
Take for example this technique:
[https://youtu.be/ljMePAmmxx4](https://youtu.be/ljMePAmmxx4)

Around 2:10 he mentions "you can actually set it for project as well" which is
a lot closer to what's being done in this case.

Blender has to solve nearly the exact same problem for projections, the only
differences being the projection has to be mapped backwards to a flat texture,
and you have to account for the way the film clings to the surface and how it
stretches. Topology and topography aren't an issue though, we've got that _so_
covered. (But the material physics is something you would have to construct a
model for, so if you wanted to solve this precise problem in Blender you might
have better results with the physics engine.)

I have seen some variation on this available in even low-end 3D modelers since
the 90s. IIRC Truespace's version of the feature did shrink-wrapping by
running a simulation, much like they do here, but with different physics.

I thought I had even seen this used in printing before but I could be
mistaken.

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ris
SIGGRAPH season already?

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dzhiurgis
Nope, Chuck Testa

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CrazyRabbit
making fake stuff become easier. now we only need to attach the printer to a
water tank.

