DINO Peer Review10 December 2003 Science Jessica Pipis Dohy Faied Paul Kolesnikoff Brian Taylor Miranda Mesloh David Goluskin

DINO Peer Review 10 December 2003

ScienceJessica PipisDohy Faied

Paul KolesnikoffBrian Taylor

Miranda MeslohDavid Goluskin

DINO Peer Review April 18, 2023

Introduction

• The purpose of the science subsystem is to take stereoscopic images of clouds in order to create a topographic map of cloud heights.

• There will be two camera’s mounted at specific angles on the satellite.

• The gathered images will be sent to the flight computer where an algorithm will find matching points. Using these points the images will be overlaid creating a topographic map which will be sent back to CU.

• Also included is a description of an algorithm and test plan.


Requirements

• The Science subsystem shall be designed to meet all of DINO’s science objectives. It will implement a stereoscopic imaging technique in order to measure cloud heights.

• Clouds imaged in the visible spectrum

• Field of view of 40-55 degrees is needed for cameras.

• Cameras will have a resolution of better than 640x480.

• Shutter speed of 1/64th of a second or faster

• Ample amount of time shall be allotted for the software system to finish processing an image before another image is required

• Each of the multiple images used to produce a topographic map of the cloud must contain the same features


Requirements

• Mass- 0.56 kg on the main satellite • Power- less than 11 Watts on the main satellite • The Science subsystem will operate on 5V and/or

12V lines• All Science subsystem components shall comply

with NASA’s safety requirements – There shall be no pressurized vessels in the science

subsystem, including the lens of each camera– All components will comply with NASA’s outgassing

specifications– Any glass components shall comply with NASA’s regulations– All components shall either be contained or meet NASA’s

requirements to be a low-released mass part


Block Diagram

Camera #1 Camera #2

C&DH

USB


The Camera

• Basic Information– Olympus C 4000– Has C-mount capabilities– Field of view depends on lens– 4.0 megapixel camera– Has USB port for data output– Maximum resolution of 3200x2400

• Does appear raw data is not available• Has TIFF format

– Advanced noise filter• Need to see if this can be disabled

– Electric variable shutter speed• 1/1000 to 16 second


Needed Flight Preparations

• Design interface for camera– USB or Flash with USB

• Write software for camera • Make or acquire lens

meeting NASA requirements

• Design mount for camera• Test


Camera Angles

• Factors influencing camera angle selection– Base/height ratio– Algorithm matching

• Illumination • Signal to noise ratio

– Larger camera angles mean smaller ratio

• Time– Movement


Influences

Base/Height Ratio• Error caused by optical

system is unchanging• Larger ratio decreases

relative error• Largest camera angle

desired

Illumination• Differences increase with

camera angle– By change in relative

position of cloud, satellite, and sun

– Time


Influences

Signal/Noise Ratio• Decreases with camera

angle• Large ratio desired for

increased accuracy of determining cloud height from stereo pairs

Cloud Movement• Increases with camera

angle• Affects algorithm’s ability

to successfully match points in stereo pair

• Smaller camera angle is preferred


Influences

•Based on:

•Altitude - 425 km

•Velocity – 7.65 km/s

Camera Angle Vs Base/Height

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 5 10 15 20 25

Angle (degrees from nadir)

Bas

e/H

eig

ht

Rat

io

Camera Angle Vs Time

0

5

10

15

20

25

0 5 10 15 20 25

Angle (degrees from nadir)T

ime

(sec

on

ds)


Simulator

• Used to simulate topography of the ground produced by stereoscopic sensing

• Influenced by factors above

• Atmosphere “magnifies” results


Results


Optimization of Stereo Pairs

• Between 10o and 20o (probably around 15o)

• Two camera layout, preferably three– Multiple pictures

• Determining along and cross track wind

• Large field of view

• Multiple layouts of camera

• Previous tables and graphs obtained from – Boerner, Anko: The Optimisation of the Stereo Angle of CCD-

Line-Scanners,ISPRS Vol. XXXI, Part B1, Commission I, pp. 26-30, Vienna 1996

–


Camera Layout With Nadir


Error in Camera Layout

10o

Nadir

30o

20o


Error in Camera Layout

• The angle between two cameras is insignificant in camera layout

• Error increases as angle between nadir and a camera increases

• Error negatively affects algorithm

• Suggests a +/- camera angle better than nadir and forward looking

-10o

+10o


Camera Layout

• Third camera preferable to normalize +/- camera views

• Can obtain nadir camera view with – Two cameras– Multiple pictures– Large field of view (dependant on number of pictures

taken)

• Can have lower resolution in vertical direction


Example

• Given– Two cameras

– Field of view of 10o

• Time – About 4.88 seconds between

pictures

– Illumination changes and cloud movement becomes insignificant

• Covers nadir and fore/aft views• Angle between fore/aft views

of 15o


Algorithm Needs Two Images

Ground Reference Point

Cloud

Camera


Cloud


Cloud

Camera


Cloud

First Satellite Position Second Satellite Position

First Cloud Image Second Cloud Image


Algorithm Combines Two Images

Cloud #1

Ground Reference Points

Cloud #2

First Images are Overlaid

•Horizontal Separation Between Matching Point on Images Determines Height

•Topo Map of Point Separation Allows Integer Math

•Point Matching Algorithm in Progress

•Use of Color and Derivative Information Likely

Cloud #1 Cloud #2

Images are Transformed to Align at Ground Level


Cloud #1


Cloud #2

Images are Shifted Until Features Match


DINO Moves in Three Axes

Pitch Φ

Yaw

Roll Ψ

Direction of Flight

• ±10° Pointing Accuracy

• ±2° Position Knowledge

• 90 min Oscillation Period


Pointing Error Moves Two Images

Cloud #1


Cloud #2

Yaw Rotated Image Pair

•Yaw Rotation is Greatest Error

•Forward Image has Rotation and Translation with Yaw Error

•Field of View Must be Large Enough to Accommodate Motion


Cloud #1 Cloud #2

No Error Image Pair


Modeling Motion Errors

z

y

x

z

y

x

*

)cos(0)sin(

010

)sin(0)cos(

'

'

'

z

y

x

z

y

x

*

)cos(0)sin(

010

)sin(0)cos(

'

'

'

z

y

x

z

y

x

*

100

0)cos()sin(

0)sin()cos(

'

'

'

z

y

x

z

y

x

*

)cos()sin(0

)sin()cos(0

001

'

'

'

Forward Camera Correction Yaw Error Model

Roll Error ModelPitch Error Model


Science Algorithm is Under Way

• Basic Algorithm Determined

• Floating Point Math Avoided

• Topo Map in Pixel Distance Saves Bandwidth

• Point Matching needs Work

• Finalizing Motion Correction Technique

• Pseudo-Code Needed• Testing Needed• Final Write-up Needed• Implementation in

Software not started


Science Subsystem Test Plan

1.Camera Operation

a. Set – up:

i. Iris (f-stop)

ii. Shutter Speed

iii. Flash Setting

iv. Focus

v. Picture type (Mode)

b. Acquisition

i. Shutter Command

ii. Accuracy


Science Subsystem Test Plan

2.Algorithma. Individual Pictures

i. Find Cloud

ii. Find Features

b. Picture Sets

i. Transform to Same Coordinate

ii. Match Reference Features

iii. Correlate All Features

iv. Generate Contours


LEGO Table Test Plan

•Flat Surface can be Mounted on Gimbal to Test Picture Angles

•Variety of Heights and Configurations can be Tested

•Ideal for Illumination Effects and Color Recognition

•Check for donation from LEGO


Commands and Sensors

• Commands from C&DH– Set up cameras– Turn on/off camera #1– Turn on/off camera #2– Take a picture– Retrieve pictures– Clear memory

• Sensors– Possible Thermistor


Parts List

• 2 Camera’s - Approx. $499 each– Olympus C4000 4.0 megapixel

• USB Cables• PC Board• Multiplexer Components• LEGO table and testing

components


Decisions Not Yet Made

• Camera angle on structure– Time between pictures

• Yaw control needed• How many pictures are

needed to determine along track wind

• What is the time delay between images


Issues and Concerns

• Camera– Problem

• The camera we are currently using doesn’t have software for USB

– Solution• We can write our own software for USB or design an interface to the flash

card

• Determining Camera angles– Depends on algorithm used

• Determining when is a good time to take pictures– Determining whether it is a good picture

• We can generate topographic maps, but they may be cloudless scenes• Probably will use color information

• Time between pictures– Time we have to take pictures vs. time we need to take pictures


Questions?

Documents

DINO Peer Review10 December 2003 Science Jessica Pipis Dohy Faied Paul Kolesnikoff Brian Taylor Miranda Mesloh David Goluskin