| Q&A |
 Angisoft
IPhone Apps,
Klaus Engel, AngiSoftware
July 2009 |
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“
QJulia visualizes a special four-dimensional fractal,
the so called Quaternion Julia set. While traditional
2D fractal visualization Apps focus on zooming into
the endless details of fractals, Quaternion Julia Raytracer
focuses on exploring the unlimited number of insanely
complex and beautiful 3D shapes that can be created
when modifying the quaternion fractal parameters. ”
<
Quaternion Julia Raytracer |
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| Q1 |
There
are more and more applications for iPhone that take advantage
of its 3D capabilities.Why are you developing 3D apps for iPhone? |
| A1 |
I'm
a computer scientist and I've been interested in 3D and mobile
graphics since i was a kid. The iPhone is an incredible device
and I'm very excited about the new GPU and compass of the iPhone
3GS. Developing iPhone Apps is just a hobby for me besides my
professional job as a researcher at a big German corporation.
In fact, i developed my first iPhone App "Galaxy Collider"
while my wife and i were waiting for the birth of our baby during
the Christmas holidays.
It's just fun to get things, that were only possible on PCs
a few years ago, running on such a small device and take them
with you. Fortunately, i do not depend financially on selling
iPhone Apps. To finance your life from developing iPhone Apps
is really hard, so you have to develop for the mass market.
With my current focus on visualization toys that is just not
possible. |
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| Q2 |
As
a developer what do you think of iPhone SDK and App store? |
| A2 |
The
App store is an incredible opportunity for developers to publish
their applications in a very professional way. I remember how
hard it was to publish my first C64 computer game when i was
a kid. I now get sales reports from all over the world - how
great it that!
The SDK is a very comfortable development environment and the
iPhone simulator and remote debugging and profiling tools are
excellent. It's tough though to get people interested in your
Apps when you are not developing party gag Apps and games. |
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| Q3 |
Could
you please describe your latest App : Quaternion Julia Raytracer? |
| A3 |
 QJulia
visualizes a special four-dimensional fractal, the so called
Quaternion Julia set. While traditional 2D fractal visualization
Apps focus on zooming into the endless details of fractals,
Quaternion Julia Raytracer focuses on exploring the unlimited
number of insanely complex and beautiful 3D shapes that can
be created when modifying the quaternion fractal parameters.
So even without artistic skills you can create beautiful images
and use them as an iPhone backgrounds. For a liquid metal look,
photographed spherical panoramas can be reflected on the fractal
shape.
The surface of the fractal is computed by tracing rays from
a virtual camera into the scene. Using unbounding volumes we
can get very close the the surface of the fractal in a few iterations,
shade the surface or compute secondary rays. The algorithm is
similar to Zeno's Paradox
of Motion.
Keenan Crane has written a
nice article about Raytracing the Quaternion Julia set
on the GPU. |
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| Q4 |
What
are the main challenges and the limitations of 3D apps for iPhone?
Developers reports low performances with antialiasing, few shaders? |
| A4 |
Of
course, memory is quite limited on the iPhone, especially on
the 2G and 3G. Though shaders programming on the 3GS works very
well, dynamic branching performance is in no way comparable
to current desktop GPUs. But besides those restrictions, i don't
see why we will not see a large number of great looking 3D graphic
Apps coming up. |
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| Q5 |
You
have also develop Galaxy Collider that combine 3D graphics and
collision : it seems that iPhone could be used for visualization
and 3D games. Can you compare the actual performances of the
iPhone and a PC? |
| A5 |
Since
the iPhone has to drive a much lower number of pixels than a
desktop system, i would compare the iPhone 2G/3G to a 1998 and
the 3GS to a 2003 desktop PC. So in other words, performance
of mobile devices is just 5-6 years behind that of desktop PCs.
For me, the iPhone is nothing else than a portable computer
anyway. The fact that you can make calls is just a nice add-on. |
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| Q6 |
iGPUTrace
shows nice spherical reflections : can iPhone reproduce photo
realistic 3D environment? |
| A6 |
Using
the programmable shaders of the iPhone 3GS will boost the image
quality of games and other 3D applications tremendously. The
jump in image quality that is possible is comparable with the
jump from a DirectX 6 PC game to a DirectX 9 game. For some
games and applications with rather simple scenes photo realistic
rendering is possible, as iGPUTrace shows. However, true photo
realism for more complex environments is not even possible on
the PC platform yet. So there are a few more years of research
and development ahead of us till that is possible. For great
games and applications however, photo realism is not that important
anyway.
Hopefully iPhone developers will take advantage of the OpenGL
ES 2.0 capabilities of the 3GS GPU and not just restrict themselves
on the greatest common denominator of all Apple devices, i.e.
OpenGL ES 1.1. |
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| Q7 |
More
and more people are planning to use iPhone camera to create
Augmented Reality App. Have you any plan for this? What would
be your next iPhone App? |
| A7 |
Augmented
reality is the next big thing on the iPhone. I expect that there
will be a real flood of augmented reality Apps. The opportunities
are endless - from virtual city guides and navigation systems,
social networking apps to multi player games that combine the
virtual and real world.
My next App world be a free-hand panorama photography App where
you could take spherical panoramas from your environment and
later watch them on the iPhone or other device. You could then
inspect places where you have been before and overlay old panoramas
with current camera images to compare how things have changed
over the years. |
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