PHOTOREALISTIC RENDERING OF SCIENTIFIC DATA

Joel Ogden

, Jabari Jordan

, Chelsey Krol

, Tanya Papazian

, Hans-Peter Bischof

and Reynold Bailey

Department of Computer Science, Rochester Institute of Technology, Rochester, U.S.A.

Department of Computer Science, Mount Holyoke College, South Hadley, U.S.A.

Department of Computer Science, Montclair State University, Montclair, U.S.A.

Keywords:

Scientiﬁc Visualization, Maya, Spiegel.

Abstract:

Generating photorealistic images of astrophysical simulations can enhance the experience of watching galac-

tic visualizations for both the specialists who study the data and the average person who is simply interested

in outer space. Unfortunately, the astrophysicist who is creating the simulations typically lacks the expertise

required to generate photorealistic images. Likewise, a 3D artist may be unaware of the physics behind cer-

tain astrophysical events. We aim to use Spiegel, a user interface that controls the rendering of astrophysical

data and Maya, a high end 3D animation program, to allow a non-artist to easily create renders of photore-

alistic images. Spiegel provides a user-friendly interface for controlling the creation of potentially complex

rendering applications by individuals with little experience in computer programming. Since Spiegel’s basic

visualization capabilities are limited to simple primitives like points and lines, it was necessary to develop an

additional program for Spiegel to interface with Maya’s 3D rendering capabilities. This software interface is

called Miegel. Using Miegel, the astrophysicist now has access to Maya’s 3D rendering capabilities allowing

them to create stunning visualizations of astrophysical phenomena. In addition, new artistic effects can be

created with Maya in the form of presets, which can be integrated into the user’s visualization with minimal

knowledge of computer programming.

1 INTRODUCTION

Visualizations of scientiﬁc processes have always

been a crucial part of education and understanding

to the student and scientist alike. Being able to see

something as opposed to reading it from a textbook

allows for a multi-dimensional learning experience

and a more dynamic understanding of complex sub-

ject matter. Unfortunately not all visualizations are as

effective as they could be. This is because most sci-

entists do not have the training or skills in modern 3D

rendering techniques to produce compelling visuals.

Spiegel (Bischof et al., 2006) was developed to bridge

this gap by bringing tool that were previously only

available to a 3D artist into the hands of the scientist.

Spiegel is a software package that allows individuals

with little or no 3D rendering or programming ex-

perience to create simulations of scientiﬁc processes

based on data. The program in its basic form is how-

ever limited to how the data is displayed. Most visu-

alizations are displayed as simple points, which take

on the roles of stars or particles. Figure 2 shows an

Figure 1: Photorealistic rendering of a black-hole merger

created using our Spiegel-Maya interface called Miegel.

example rendering created using Spiegel’s basic ren-

dering capabilities. We created Miegel, a software in-

terface that allows Spiegel to take advantage of the

rendering and animation capabilities of Maya. By us-

ing our system, the user is able to create more realistic

and appealing visualizations such as the one shown in

Figure 1.

719

Ogden J., Jordan J., Krol C., Papazian T., Bischof H. and Bailey R..

PHOTOREALISTIC RENDERING OF SCIENTIFIC DATA.

DOI: 10.5220/0003851207190724

In Proceedings of the International Conference on Computer Graphics Theory and Applications (IVAPP-2012), pages 719-724

ISBN: 978-989-8565-02-0

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

Figure 2: A visualization of a black-hole merger created

using Spiegel’s basic rendering capabilities. The stars are

displayed as 3D points.

Figure 3: Overview of the Spiegel framework. Data is ex-

tracted from one or more ﬁle servers and distributed to a

cluster of computers. Each processing unit in the cluster

generates one (or more) frames of the complete visualiza-

tion sequence in parallel. These frames are then combined

to create a video. Image courtesy of (Espinal et al., 2010).

2 SPIEGEL

Spiegel is a software package that allows users with

little experience in 3D digital graphics or computer

programming to create visualizations based on raw

simulation data. Spiegel makes this possible through

a graphical user interface that allows users to com-

bine components to create their desired visualization.

Each component represents an individual program de-

signed to perform a speciﬁc task. The Spiegel system

is designed to be extensible by allowing new compo-

nents and functionality to be added to the basic frame-

work. This is possible because Spiegel is designed

using a data ﬂow architecture. Components have

communication endpoints, which can be connected

to form a complete visualization program. When the

Figure 4: Example of a program created in Spiegel that il-

lustrates the data ﬂow architecture. Image courtesy of (Es-

pinal et al., 2010).

program is executed, data is passed from one compo-

nent to another. Each component performs speciﬁc

operations that contribute to the ﬁnal result (Espinal

et al., 2010). Communication between components

is made possible by a variety of built-in data struc-

tures (Bischof and Dong, 2011). Data is taken in via

an extractor and placed in these structures which are

then passed between components as optional param-

eters. Figure 4 shows a simple visualization program

created using Spiegel’s graphical user interface.

3 PREVIOUS WORK

Spiegel’s basic rendering capabilities are provided us-

ing OpenGL primitives such as points and lines. As

can be seen in Figure 2, the resulting renderings are

useful but not necessarily compelling or realistic.

Several efforts have been undertaken to improve

the quality of the renderings produced by the Spiegel

system. One such effort expanded the visualization

capabilities of Spiegel by using Pixar’s PhotoRealis-

tic RenderMan



(Cassidy et al., 2011). By using the

shader library accessible through the RenderMan



program, the researchers were able to apply displace-

ment shaders to better represent stars and other cos-

mic forms. They also used noise patterns and color

palettes to develop realistic models of stars. A fur-

ther advantage of RenderMan



was its ability to in-

corporate realistic lighting effects, which proved to

produced far more compelling visualizations.

In addition, other work has been done to study

the gaze patterns of expert and novice astrophysicists

to gain insight into what makes a favorable or com-

pelling visualization (Arita et al., 2011). By hav-

ing participants view a number of images of galactic

events, both photographed and computer generated,

the researchers were able to gain a better understand-

ing of preferred camera positions and zoom settings.

This information was then used to modify existing

Spiegel visualization programs to create more favor-

able renderings.

Despite these advances, the improved Spiegel

framework had several major drawbacks. In partic-

ular, developing custom shaders for the RenderMan



component required signiﬁcant programming exper-

tise. Furthermore, the system still lacked the capa-

IVAPP 2012 - International Conference on Information Visualization Theory and Applications

720

bility to handle complex animations and ﬂuid simula-

tions.

To overcome these limitations, we decided to use

Maya because of its ability to produce compelling

visualizations with minimal programming. Further-

more, Maya has a robust ﬂuid simulation system

and the ability to store artist created presets, which

novices can easily access. This ﬂuid system proved

to be the ideal solution for simulating space dust and

gases.

4 MAYA

Maya is a high-end 3D animation program capa-

ble of producing stunning visual graphics. A major

shortcoming is that it takes a considerable amount of

time and training in order for an individual to pro-

duce these images. Through the Miegel (i.e. Maya-

Spiegel) interface that we created, the user can take

preset ﬁles created by an expert in the use of Maya

and insert them into the scene with relative ease. Us-

ing the controls provided in the Miegel interface, the

user can also customize the visualization by simply

adjusting various attributes.

In order to produce the visual effects of space

dust and gases, we utilized Maya’s ﬂuid simulation

system. Through the careful application of noise at-

tributes and color gradients we were able to construct

cloud shapes that were much like those seen in galac-

tic imagery. These settings were then saved as presets,

which allow for faster render times and greater con-

trol. These types of presets can easily be loaded and

adjusted by a novice user to quickly create appealing

visualizations.

Another powerful feature that Maya provides is

the ability to map an image onto a ﬂuid. This is done

by using the color values of the image to represent

speciﬁc densities in the ﬂuid. Maya’s ﬂuid simulator

can then use this information to produce the effect of

vortices and cloud formations (Brinsmead, 2007). We

were able to add further detail and realism to the ﬂuid

simulation through the use of photographs of various

cloud formations made available through the National

Oceanic and Atmospheric Administration, as well as

other open source venues. This same technique can be

applied for any photographed astrophysical phenom-

ena, allowing for an added degree of dimensionality

to the visualization. By utilized Maya’s wide array of

physically accurate modiﬁers, we were able to manip-

ulate the ﬂuid as if it were acted upon by forces found

in space.

5 MIEGEL

Miegel is a software interface designed to integrate

Maya’s rendering capabilities with Spiegel. Miegel

was created because the existing solutions provided

by OpenGL and RenderMan



were too complicated

for novices to use since they required signiﬁcant pro-

gramming experience. The process of adding new

types of effects to the visualization pipeline, for ex-

ample, required many hours of implementation, test-

ing, and debugging. Miegel accomplished this by us-

ing the options available through Maya to produce

stunning visualizations, which in tern require less pro-

gramming hours. In addition, Miegel aimed to allow

for visuals produced by a 3D graphics artist to be eas-

ily integrated into the visualization. With Miegel, the

task of creating visual effects such as those seen in

professional productions as well as the process of in-

tegrating them into the visualization is greatly sim-

pliﬁed. This is done by the user interface in Miegel,

which allows for visuals produced by a 3D graphics

artist in Maya to be easily integrated into the visual-

ization through a drop-down menu. The applicable

attributes of the speciﬁc preset are then displayed for

the user to modify, giving the user full control over

the aesthetics of the ﬁnished rendered image.

Miegel works by producing a MEL (Maya Em-

bedded Language) script and a data cache PDC (Parti-

cle Disk Cache) and passing them to Maya. The MEL

script contains information about the objects Maya

should create, such as color and luminance values for

the given particles, as well as scripts to import addi-

tional scene ﬁles. The PDC is a raw ﬁle format used

by Maya as a way of caching information about the

particles. The cache maps attribute information about

particles to disk allowing for faster drawing of par-

ticles, versus having to re-calculate the positions for

each particle for each frame (Center, 2005). The PDC

contains the vector data for the particles that repre-

sent the stars in the simulation. Maya can then ren-

der this out into a batch of image ﬁles, which can be

at full HD resolution (in contrast with the previous

solution which could only produce standard resolu-

tion images). The big advantage with this system is

that Miegel automates most of the process and allows

users unfamiliar with Maya to still take advantage of

its powerful capabilities.

Figure 5 illustrates the Miegel architecture. A

MEL script is a language provided by Maya that

allows users to create macro programs to automate

many of Maya’s functions and operations. Because

the Maya GUI is itself written in MEL, any operation

that can be performed by a human using Maya can

also be programmed in MEL. This means that a pro-

PHOTOREALISTIC RENDERING OF SCIENTIFIC DATA

721

gram like Miegel that generates a MEL script can

perform any action in Maya that is available to a

user. The simplicity of MEL scripts mean that Miegel

can easily be expanded to utilize any of Maya’s fea-

tures (Autodesk, 2010).

An example of a MEL script is

particle n star p 0 0 0;

setAttr star.prt 8;

setAttr particleCloud1.incandescence

type double3 1 1 1;

setAttr particleCloud1.glowIntensity 1;

These few lines instruct Maya to place a single

particle named star at vector (0, 0, 0), convert the type

of the particle to a cloud, then change the incandes-

cence color to white with maximum glow. Once this

single particle is created, it can be attached to the PDC

that contains all of the particles (potentially tens of

thousands) and an image that matches the data in the

simulation can be rendered. Scripts such as the one

shown above are automatically generated by Miegel

and utilized by Maya to produce the resulting image.

Spiegel utilizes simulation ﬁles with the exten-

sion .sim. A sim ﬁle is a human readable ﬁle writ-

ten in plain text, which contains information such as

the number of stars in the simulation, the positions

of the stars for each frame, as well as their velocity,

acceleration and other information. Miegel creates a

disk cache ﬁrst be parsing out information from the

sim ﬁle. For the purpose of the visualization, we only

cared for the positions and frame number of the stars.

To convert the .sim to PDC, Miegel makes two passes

over the .sim ﬁle. First, the positions of the stars and

their frame number are extracted, at the same time

ﬁlling any gaps in the data. This information is then

written as raw bytes into an .msf (Maya-Spiegel For-

mat) ﬁle. From here, Miegel can quickly extract the

data for any particular star in ﬁle from any frame. The

beneﬁts of having the .msf ﬁle is that the .sim ﬁle

only has to be parsed once and any subsequent vi-

sualizations using the same data does not have to be

run through the converter again. For reference, a 7GB

.sim ﬁle took over an hour to be convert to msf. Other

beneﬁts of the .msf format include a much smaller

ﬁle size and predictable data placement allowing for

close to real-time access of information, this allows

for frames deep in the simulation to be quickly ex-

tracted and used for the visualization.

After the MEL script is generated and the PDC

completed, Maya can read the script and output a

Maya scene ﬁle (.ma) which holds all the information

needed by the renderer. The .ma ﬁle is the standard

ﬁle format used by Maya that can be read and edited,

allowing Maya users to verify the visualization before

Miegel

Visualization

Attributes

Simulation Data

Interpreter

Maya Scene Files

Maya 3D

Maya Renderer

MEL Script

Generator

Particle Disk

Cache Creator

Maya Scene File

Spiegel

Visualization

Settings

.sim to .msf

Convertor

Maya Effects

Importer

Figure 5: Architecture of Miegel. The Simulation Data In-

terpreter takes the position data of the stars, and creates the

Particle Disk Cache, which is needed for Maya to map the

location of the stars to the particles objects. The visual-

ization attribute module takes in information from the user

about the desired appearance of the stars (including color,

size, and glow intensity) and produces a MEL script. The

script can also include instructions to integrate other Maya

ﬁles into the visualization. Once the script is generated, it

is executed by Maya to produce the individual frames of the

visualization.

rendering and import other Maya scene ﬁles. The .ma

ﬁle is read by the Maya renderer to produce the ﬁnal

images. The render can be ﬂagged with arguments to

change the attributes of the outputted ﬁle, such as res-

olution, and what rendering techniques it should use,

such as anti-aliasing. This provides other advantages

over the OpenGL and RenderMan



solutions, where

such features must be explicitly programmed.

Spiegel components were created to allow for easy

access to Miegel from Spiegel. A user familiar with

Spiegel can easily use the new Miegel component to

access Maya. The user can import the required simu-

lation ﬁle, then choose which frames in the simulation

to render. Furthermore, they can import as many 3rd

party Maya scenes that are available, having access to

IVAPP 2012 - International Conference on Information Visualization Theory and Applications

722

Miegel

Visualization

Attributes

Simulation Data

Interpreter

Maya Scene Files

Maya 3D

Maya Renderer

MEL Script

Generator

Particle Disk Cache

Creator

Maya Scene File

Maya 3D

Simulation.msf3

Extractor

Clock

Miegel

Star Attributes

(Colors, size, etc.)

Space Cloud

Effects.ma

Background

Stars.ma

Maya Renderer

Start, Stop, FPS

Rendering

Settings

Maya File

Importer

Figure 6: : The Spiegel components available to the user

and how they interact to produce visualization.

easy to use sliders and drop down boxes to choose at-

tributes, which change the look of the stars as well as

the image output format, location, resolution, as well

as other renderer attributes. Figure 6 illustrates how

the information ﬂows through Spiegel into Miegel and

the renderer.

Figure 7: Maya viewport view of the simulation.

6 CONCLUSIONS AND FUTURE

WORK

We have created a highly customizable and robust

program called Miegel that is able to take simulation

data in its raw form from Spiegel and send it to Maya

to generate compelling visualizations. This allows the

user to utilize the full gambit of Maya’s capabilities

in Spiegel in order to further enhance their visual-

ization. With Miegel, Spiegel could be expanded to

use professional grade animation programs to better

its ability to create realistic and eye catching simula-

tions. This provides the ability to add numerous spe-

cial effects and/or programs to Spiegel in the future.

In future work it would be possible for the user to use

the integrated camera capabilities, allowing for nearly

seamless incorporation of stereoscopic cinematogra-

phy into scientiﬁc simulations. Maya also has soni-

ﬁcation capabilities, allowing the user to coordinate

sound with the aesthetics of the visualization, which

would greatly enhance the viewing experience. Maya

also allows the use of it’s diverse library of shaders

and the ability to create customizable shaders, giving

even greater customization to the aesthetics of scene.

In addition, Maya’s newest release has the capability

to render images using a GPU based rendering system

that has the capability to display these images in the

viewport in their rendered state. Figure 7 shows the

viewport view in Maya of a simulation that was gener-

ated from our program Miegel. It is entirely feasible

to integrate other animation and rendering programs

into Spiegel, which will better enhance the simula-

tions that are produced. The framework we have cho-

sen allows for the addition of any preset the user may

require, giving the program an endless potential for

expansion that is only limited to one’s imagination.

ACKNOWLEDGEMENTS

This material is based upon work supported by

the National Science Foundation under Award No.

0851743. Any opinions, ﬁndings, and conclusions or

recommendations expressed in this material are those

of the authors and not necessarily reﬂect the views of

the National Science Foundation.

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