Spacecraft Solar Arrays Shading Visualization

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Copyright © Capstone Team # 1


SPRING 2010 CSCI 6838

Page
1

of
7



Spacecraft
S
olar Array
s

S
hading
V
isualization


Spring
-
2010

Software Requirements Specification

Document


Instructor:

Dr.Alfredo Perez
Davila


Project
Mentor:

Peter Armstrong


Capstone
Project Team Members:

Ajay chand Jasti

Suman Babu Alapati

Vamsi Krishna Guntupalli

Karthik Bhuvanagiri

Venkata Naveen Aluru







Copyright © Capstone Team # 1


SPRING 2010 CSCI 6838

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Table of Contents



1.Introduction…………………………………………………………………
.
..
....
3


1.a

Purpose……………………………………………………………………

3


1.b
Sc
ope………………………………………………………………………...
3


1.c
System Ov
erview…………………………………………………………….
3


1.d

References……………………………………………………….. ………… 4

2
. Definitions, Acronyms, and Abbreviations …………………………
………
….

4


3
. Use Cases …
…………………………………………………………………
….
5, 6

4
. Functional

requirements…
…………………………………………………
…..
.6,
7

5
. Non Functional requirements…
……………………………………………
…….
7






Copyright © Capstone Team # 1


SPRING 2010 CSCI 6838

Page
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1.

Introduction


W
e shall

create an application that visualizes the International Space Station in a simplified Earth
orbit.
A 3D game engine, Unity which is

used
for creating simple graphics is used to assist us in
creating the application. T
he solar
arrays

which are a part of the ISS will
cast shadow
s

all the
time

when sunlight falls on them and
we need to graphically visualize this

and shall provide a
graph
ical output showing the area of the solar arrays that is shaded due to sun light
.

a.

Purpose

The

main purpose of this document is to serve as a
b
ind
in
g

agreement regarding the
requirements of the project.
The objective of this project is to graphically mode
l the shading

of
sunlight on the solar arrays

of an orbiting spacecraft and analytically determ
ine the area of the
shaded region of the solar arrays
. And also we shall be calculating the optimum orientation of the
ISS to

maximize the
amount of sunlight
reaching the solar arrays
.

b.

Scope

This d
ocument contains a complete description of the functionality of the project. It consists of
use cases, functional requirements and nonfunctional requirements, which, taken together form a
complete description of the s
oftware
.


c.

S
ystem Overview



A 3D game engine, Unity,
shall

be used to render the visualization of the spacecraft.



The o
verall application is implemented in
Unity
;

we
shall

build an application that visualizes
the International Space Station in a simplified Earth orbit.



The solar arrays
shall

rotate to orient themselves to face the direction of the sun.



This document covers the set of requirements to implement the applicat
ion.



The proposed application
shall

provide a 3D visualization of the orbiting spacecraft and
accurately show the relationship of the sun and shadows upon the structure of the spacecraft.



The application
shall

render realistic shadows that structure of the

spacecraft casts onto itself.



The application
shall

determine the area of the solar arrays that are in shadow

d.

References



http://unity3d.com/unity/features/iphone
-
publishing



http://www.nasa.gov/mission_pages/station/main/index.html



http://3dbuzz.com/forum.html



http://unity3d.com/support/documentation/Manual/index.html



“An algorithm for the Shading and Blocking Computations of a Fi
eld of Heliostats Arranged
in
Grid Layout”

by Peter Armstron
g

Tietronix Software, Inc




Simple Keplerian (2
-
Body) Motion
” by
Peter Armstrong

Tietronix Software, Inc





Copyright © Capstone Team # 1


SPRING 2010 CSCI 6838

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2.

D
efinitions, Acronyms, and Abbreviations


ISS


International space station.

UTC


Universal Coordinated Time.

Unity
-

A 3D

program used for creating game
s
.

Asset


Objects used in the
Unity

program to create graphics.

Scenes
-

Scenes

contain the objects of the game
.

Project View


The project view contains the contents of the assets folder.

Scenes


Scenes
shall

be defined as
individual levels in a game.

Parenting


Parenting is the process in which a
game Object

is made the child of another
game
Object
.

Scene View


Scene view is the interactive view where we place objects, environments and
control the camera angle.

Game View


Game view is the final view where we
shall

only view the final output of our
resources.

Status Bar


The status bar shows us the status of the compiling process and the log output.

Prefab


Prefabs contain a collection of
game Objects
.


















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SPRING 2010 CSCI 6838

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3.

Use Cases:


Overall use case diagram




i)


User controls camera






Description:

User opens the project in
Unity

and he
shall

be controlling the direction of the camera to view
the sun and earth and the ISS from different views.

Normal Flow:



User opens
the project
.



User shall enter the position coordinates for the camera or
shall

control that by using the GUI



The view
shall

be updated to the specified coordinates.



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ii)
User inputs epoch







Description:

User opens the application in the
Unity

web browser and then he
shall

be able to input the time
and control the time and pause the time.

Normal Flow:



User
opens the project
.



U
ser shall

input the epoch (year, month, day, hour, minute, second in


Universal Coordinated Time (UTC))



The user

shall

pause the time, reset the time to the element set epoch, reset the time to the
current (real) clock time, and advance the time forward or backward in 1x, 10x, 100x, and
1000x multiples of real time.

4.

Functional requirements


1)

The ISS 3D model shall
represent the ISS in its final configuration.

2)

The application shall compute the position of the sun with respect to the Earth and ISS. The
application shall use the algorithm for sun position from the paper “An algorithm for the
Shading and Blocking Comput
ations of a Field of Heliostats Arranged in a Grid Layout.”

3)

The application shall rotate the ISS
such that
solar arrays are perpendicular to the direction of
the sun.

4)

The application shall render shadows as they are cast from the ISS structures onto the s
olar
arrays, including shadows from solar arrays onto other solar arrays.

5)

The application shall compute the area of each solar array that is in shadow.

6)

The application shall numerically display the shaded area of each solar array, in square
meters, and the

percentage of the array that is in sunlight.



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7)

The application shall model the motion of the ISS
in an orbit
as
mentioned in paper

simplified Keplerian (2
-
body) orbit
” and

shall
continuously update the position of the ISS in
the Unity 3D visualization.

8)

The

application shall allow the user to input the epoch (year, month, day, hour, minute,
second in Universal Coordinated Time and the following Keplerian elements of the ISS:

a)
Semi
-
major

axis in meters
.

b)
Eccentricity
.

(
Unit
less

number between 0 and 1, inclusive)

c)
Inclination

in degrees
.

d)
Right

ascension of the ascending node in degrees
.

e)
Mean

anomaly in degrees
.

f)
Argument

of periapsis in degrees
.


9)

The user
shall

control the motion

and direction

of the camera


Name

1)

Control of epoch

Summary

Application allows the user to input the epoch and control the time
frame.

Rationale

In order to visualize the shading of the solar arrays at multiple
instances of time with respect to sun’s position and also to visualize the
sha
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the time

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5.

Non Functional
requirement

The application is developed in Unity game engine, where we will be importing the assets like
ISS and 3D model
of Earth and a point source of light which will act like sun.