Our next topic is Dynamic Illustrations.

And the work we introduce here, is

called sketch based dynamic illustration of fluid systems.

And the program we want to address here,

is that it is tedious to illustrate fluid flow.

Suppose you have a engineering system or architecture.

Or organic shapes or a liver system.

There is a lot of fluid systems, and you may want

to describe how the fluid flow in these kind of systems.

And then you want to get these kinds of results.

And it's very tedious to draw them manually.

So, our idea is to use automatic flow simulation

to automatically synthesize this kind of data for illustrations.

So here, the simulation is not used for prediction,

but this is used for a niche [UNKNOWN] illustration.

So let me show you a video

[BLANK_AUDIO]

So this is basically a drawing system.

You draw something, and the system

continuously runs fluid simulation behind the scenes.

And they add fluid flow visualizations automatically.

So you draw something, a region.

And then you draw pipes.

And then as soon as you finish drawing

a system, system starts flow simulation behind the scene.

So it visualize a, a detail flow, and also shows the result of fluid mixtures.

[BLANK_AUDIO]

So this tool is very useful for explaining fluid phenomenons.

[BLANK_AUDIO]

So you can interactively edit the shape by deformation tools.

[BLANK_AUDIO]

Okay.

So an, our [UNKNOWN] example is here

[BLANK_AUDIO]

So here we use these two for explaining surgical operations for a defected heart.

So here is an example.

So here this heart has very specific configuration.

And not very ideal.

And here ideally blue blood come from the body, should directly

go to the lung, and then from the lung, fresh blood, red

blood comes into the heart, and then red one should go through the body,

however here blue blood is mixed together with red one.

And then purple one go to the body.

So, doctors will perform a surgical operation to fix this.

However, before they that, they need to explain what

they do to their patients, or their patients' parents.

However, it's very difficult to do that with

standard tools, currently, they use standard pen and ink.

Black and white illustration to describe them,

however, it's very difficult to understand it.

But preparing this kind of beautiful illustration using computer

system, is too time consuming, and more importantly, this kind

of heart disease has different configuration for each patient,

so it's not possible to prepare a template before hand.

So, this kind of tool can be very useful.

To explain and understand complicated flow phenomenon.

And then let me show you how it works.

So first, the

operation start with connecting the locations, and

then they will change the configuration here.

So doctor cuts here and then connect them.

So, as soon as the configuration changes,

the fluid simulation changes the flow, prediction.

[BLANK_AUDIO]

So next one is the most important one.

The doctor stops here, cut here, and then connect here.

And therefore, blood suddenly changes.

[BLANK_AUDIO]

And finally, in closing this hole and then

let blood directly go to the body, being red.

[BLANK_AUDIO]

And this kind of technique can be very useful for various

fluid phenomena inside of your body, like blood circulation and others.

[BLANK_AUDIO]

And also this technique is, can be used for engineering systems.

Like this one.

[BLANK_AUDIO]

And this is another example in [UNKNOWN] so you can see

how cold air and le warm air mix together and flow.

And you can test many different configurations.

[BLANK_AUDIO]

And this tool can be also used for,

for explanation of pollution of rivers, and so.

And so now let me describe the other region briefly.

So what we use is a hybrid fluid simulation system.

So user draws global network with local regions.

And we apply different simulation [UNKNOWN] for different scale.

Because single scale simulation can be very slow.

So, for a global network simulation, we use simple hydraulic simulation.

And therefore, individual local region, we use hydrodynamic simulations.

And so, to use a [UNKNOWN] node inflow, and there forms

a global network structure, hydraulics compute it's pipe flow and the

node pressure, and then from this node pipe flow and node pressure, hydrodynamics

computes a detailed, computes detailed flow, inside of this region.

So this is a little bit in too involved, but let me describe the way.

The first line is hydraulics simulation for a global network.

Here, input is node inflow Qn, so how much flow comes in from the node.

And then what we compute is pipe flow from node inflow.

And hydraulics is a simplified computational method directly computed

from compute from node inflow, and to get a pipe flow.

And after pipe flow, we can compute a pressure, pressure drop at this pipe.

And then from pipe pressure drop, we can

compute the node pressure inside of each node.

And you can get these all information by solving a linear global system once.

It's very fast and it's very efficient.

And after computing pressure node, and [UNKNOWN] pipe flow, we

now switch to our regional [INAUDIBLE] so for each local region.

We compute we divide into a lots of grid cells

like this one, and for each grade cell, we compute pressure

and velocity, and in order the compute individual pressure and velocity, we

use a very standard established fluid equation called Navier-Stokes Equation.

So this one is a little bit complicated, but

essentially this just explains the relationship with fluid velocity

and fluid pressure, you know, if there's a huge

difference in fluid pressure, and it causes velocity, and so.

And this step basically just solved this equation times

step, each time step on this grid cells inside each region, to get an animation.

So so original paper was published as

sketch based dynamic illus, illustration of fluid systems.

And if you want to learn more about fluid

animation, I recommend you to read some text books.

One example is Fluid Simulation for Computer Graphics by Bridson.

And this work is an example

of illustrative animation for facilitating understanding.

And interesting early dated work

is, MathPad, which takes mathematical [INAUDIBLE]

expression, and they automatically generates

animation, based on the mathematical expression.

So that's, this is the end of our

second week of this Interactive Computer Graphics course.

We described dia, diagram beautification.

And [INAUDIBLE] shape manipulation, and also

dynamic illustration with a fluid simulation.

Thank you.

2-4 Dynamic Illustrations

Interactive Computer Graphics

Meet the Instructors