The study of the Earth as a system will require the merger of scientific and data resources on a much larger scale than has been done in the past. New methods of scientific research, particularly in the development of geographically dispersed, interdisciplinary teams, are necessary if we are to understand the complexity of the Earth system. Even the planned satellite missions themselves, such as the Earth Observing System, will require much more interaction between researchers and engineers if they are to produce scientifically useful data products. A key component in these activities is the development of flexible, high bandwidth data networks that can be used to move large amounts of data as well as allow researchers to communicate in new ways, such as through video. The capabilities of the Advanced Communications Technology Satellite (ACTS) will allow the development of such networks. The Pathfinder global AVHRR data set and the upcoming SeaWiFS Earthprobe mission would serve as a testbed in which to develop the tools to share data and information among geographically distributed researchers. Our goal is to develop a 'Distributed Research Environment' that can be used as a model for scientific collaboration in the EOS era. The challenge is to unite the advances in telecommunications with the parallel advances in computing and networking

Abbott, Mark R.

English

NASA Technical Reports Server

NASA-CR-!91940
FINAL TECHNICAL REPORT
NASA GRANT # NAGW-2339
;/v- x/'3 -et2,,,-"
O'
,O
¢-4
I
o_
Z
Z
_._=.
t_
0
0
O0
_tZ
0_
r=4
O_-
,-4Z
I Lu
I 0
tmW
_W
U
C
0
OJ
ev
U
._,
C
U_
Q; ,
_mm
F- C
_c 4a
_n_a
0
OJ
_J
_t
0
r_
_t
t_
0
Mark R. Abbott
College of Oceanography
Oregon State University
MODIS Algorithm Development and Data Visualization Using ACTS
Abstract
_e study of the Earth as a system will require the merger of scientific and data resources on a
much ]argc c scale than has been done in the past. New methods of scientific research, particularly
in the development of geographically dispersed, interdisciplinary teams, are necessary if we are to
understanc! the complexity of the Earth system. Even the planned satellite missions themselves,
such as the Earth Observing System, will _uire much more interaction between researchers and
engineerc ff they are to produce scientifically useful data products. A key component in these
activitie,; is the development of flexible, high bandwidth data networks that can be used to move
Iarg_., araounts of data as well as allow researchers to communicate in new ways, such as throu_,h
video. The capabilities of the Advanced Communications Technology Satellite (ACTS) will allow
the development of such networks. The Pathfinder global AVHRR data set and the upcoming
SeaWiFS Earthprobe mission would serve as a testbed in which to develop the tools to share data
and infz.rrnation among geographically distributed researchers. Our goal is to develop a "Distributed
Research Environment" that can be used as a model for scientific collaboration in the EOS era. The
_halleage is to unite the advances in telecommunications with the parallel advances in computing
and networking. ::
Rationale
The study of the Earth as a system will require enormous resources in terms of data, computer
power, and scientific talent. The inherently interdisciplinary nature of the research, as well as
its complexity, will require the development of new methods of scientific communications and
collaboration to marshal these resources into an effective research program. It is no longer realistic
to expect that an individual researcher, no matter how talented, can grasp the complexity of the
Earth system and the associated data sets and tools necessary for its study. The proliferation of local
research teams gives testimony to this need for group-based research.
In the past, such research groups typically have been based at a single institution with perhaps
a few members located at other locations. With the advent of EOS, this "local mode" has been
replaced by a more "distributed research mode" where collaborative scientific investigation requires
2
_=RECEDING P._GE BLAr.IK NOT FILMED
ORIGINAL PP,GE _:_
OF POOR QUALITY
https://ntrs.nasa.gov/search.jsp?R=19930007570 2020-03-17T09:23:09+00:00Z
the involvement of researchers at geographically dispersed institutions. However, collaboration using
typical tools such as telephone and travel is difficult to maintain because of the need for flexible,
"impulsive" contact between researchers, as well as the increased number of nodes that participate
in a given investigation. As electronic networks have expanded, it has become somewhat easier to
share data and information through file transfers and electronic mail so that distant team members
can participate as effective members of the team. Networking has expanded the "base" of potential
collaborators such that a researcher may belong to several groups that arise and disappear over time
periods from a few months to several years.
The principal obstacle to such effective collaboration in the future will be inadequate communications
bandwidth. The dilemma facing scientists is that as networking expands, performance often decreases
because an increased number of users are demanding increased services. It is much the same dilemma
that faces transportation planners; as soon as new highways are built, demand generally exceeds the
capacity. While ground-based fiber systems will play a vital role in this improvement of networking
capacity, it is not a complete solution. It will be several years before fiber reaches every researcher.
Also, such fixed links do not allow much flexibility in network configuration, nor do they account for
the degradation in performance that will occur as traffic leaves the high speed backbone for the local
networks or as the networks become overloaded. It is analogous to estimating travel time simply by
measuring distance between two cities without accounting for the delays that will occur as traffic
moves through various low speed roads in towns, villages, etc. High speed fiber backbones are best
suited for systems where there is a predictable, high volume load, such as between supercomputer
centers.
The explosion of data from both space and ground/sea based sensors, and the increased level of
collaboration that characterize EOS places strong demands on the communications network that
will permit scientists to distribute data products and information in an interactive framework and
in a timely fashion. Data from satellite and m situ sensors must be transmitted to processing and
analysis centers, and the processed and/or blended products must be broadcast to a client Community
that is geographically dispersed. Interactive data analysis with scientists from remote institutions
will require digital teleconferencing and integrated video data exchange. Current communications
networks will be insufficient to meet the need.
The Advanced Communications Technology Satellite (ACTS) has several unique features which
make it ideal for addressing these communications problems in the Earth Sciences and ACTS
will provide a valuable adjunct to high speed ground networks. With its ability to deliver high
bandwidth associated with the multibeam communications package, which includes both fixed and
hopping beams, along with its flexibility in terms of network configuration, it will be possible to
build up and tear down networks as the need arises. It is particularly well-suited to the "burst" or
"bandwidth on demand" mode of traffic as occurs during occasional transmission of large data sets,
video servers, or teleconferencing. The challenge is to integrate ACTS capabilities into existing
network services so that the user is unaware of the exact nature of the physical link underlying the
communications channel.
By utilizing existingdatastreamsandterrestrialcommunicationspaths,one couldestablisha "Dis-
tributedResearchEnvironment"amongthree institutionswhich will thenserveas a model testbed
for future developmentof the ACTS network after launch in 1993. We see the communications
networkasone of thekey weaknessesto achievingsuccesswith EOSandthereforebelievethatthe
ACTS-basedcommunicationsconceptin the shouldbe advocatedin the EOScontext.
Results
There are four general areas where ACTS could make a unique contribution to the EOS commu-
nications network.
First, remote data collection platforms at sea and in the terrestrial environment will be increasingly
be used both for direct capture of satellite observations (i.e. HRPT transmissions) and to provide
observational data from ground or sea based sensors. The requirement will be for transmission
of these data to remote analysis and processing centers. Current remote platforms are severely
bandwidth limited; the capability of vastly increased multipoint to point data communications paths
with high bandwidth will immediately open many new observational opportunities.
Second, ACTS could provide a point to multipoint distribution network for derived products resulting
from EOS sensors. For example, data from distributexl earth station reception could be merged at
a central location to form, say, a sea-surface temperature map of the U.S. coastal waters, and
distributed to a wide range of researchers interested in the using the product for input into numerical
models of for further researcher-specific analysis.
Third, geographically dispersed researchers could use the network capabilities for joint interactive
data analysis. The combined video, data and voice requirements place high bandwidth demands,
even with digital compression. Many researchers are not and likely will not be accessible by fixed
land lines. Interactive applications and teleconferencing are very sensitive to high latency. Satellites
have often not been considered a viable solution due to the delay incurred by the two round trips
to geosynchronous orbit that the connection must take. With its on board routing, ACTS eliminates
one of those hops and can compete favorably with the land based Internet. Its high bandwidth and
flexibility also make it a viable solution for video and data analysis teleconferencing.
Finally, ACTS could act as an advanced TDRS for point to point transmission of satellite data
to ground stations. This would improve the current limitations in the amount of data stored and
transmitted during the time the satellite is in the field of view of the receiving station and opens
opportunities for distributed data reception of specific data streams to a distributed data analysis
network.
Future Capabilities
Publishing results and corresponding with peers is the backbone of scientific research. It allows
researchers to make their findings known to a wide audience. Unfortunately, as science and
technology progress, this body of knowledge will grow at an ever increasing rate. It is difficult
for a scientists and engineers to follow all relevant journals in their particular field, let alone explore
other fields for relevant information. Present methods of publishing are too slow, not in a digital
format, and offer only a tiny fraction of the actual data and work that went into their making.
It is often difficult to retain the knowledge base that went into the development of a particular
scientific idea, paper, or model. Present solutions generally have inadequate bandwidth and are
ephemeral. That is, there is little corporate memory or any methods to retrieve the various paths, dead
ends, intermediate data sets, comments, brainstorming sessions, etc. that are essential to scientific
understanding. The result is an incomplete record; a complete record would prove invaluable not
only in allowing other researchers to recreate the process used to develop the theory, but also for
teaching.
With the increasing amount of data and processing that goes into a research paper, printed media
will become increasingly inadequate at conveying the information. More and more researchers will
request access to the raw or partially processed data to verify or extend the research. The "paper"
will also incorporate a wide variety of data types, ranging from model code and visualizations, to
records of audio and video conversations. CD-ROMs appear to be a useful form to maintain these
"papers" and the associated data sets. Researchers may wish to access these CD-ROMs over the
network, much as they can browse through fibrary listings. This again requires a high bandwidth
network connect in order to transfer the data in a reasonable time.
Similar statements can be made about video servers. As numerical models produce increasing
volumes of data, we expect that video animations will become an increasingly common tool for
display and analysis of model output. The difficulty with this medium is that it is expensive to
duplicate and distribute to the science community. One might store such animations on a video
server, much as there are news and mail servers on Internet at present. This would allow researchers
to access video segments of interest for playback on their local workstations.
Shared-X from Hewlett-Packard is an example of a software system that allows users to view
identical windows on distributed workstations. Applications running under the X windowing system
can be displayed simultaneously on multiple machines. All participants may interact with the shared
application and have their actions distributed to the other participants. This system, coupled with
an audio link, would allow scientists to examine common data sets in a manner that is quite similar
to what can only be done locally now. The North Carolina Supercomputer Center is developing a
similar system for model manipulation and visualization.
Oneof the limitations to Shared-Xandsimilar projectswill beavailablebandwidthto remotesites.
Bitmapscanbe manyhundredsof kilobytes in size. The ability to display them quickly requires
high bandwidthbetweenthe datasourceand the remotedisplay. In a local environmentwhereall
machinesare likely to beconnectedwith a 10Mb/s Ethernet,the networkperformanceis usually
acceptable. The Internet backboneis only presentlybeing upgradedto 45 Mb/s (DS-3). With
hundredsof usersnationwide,only a tiny fraction of this bandwidthwill be available to a single
user. This will causea severedrop in performancewhenan applicationis sharedbetweenremote
sites. A communicationssatellitewould be an ideal solutionas it has the necessarybandwidth,
canbe easilyreconfigured,andevenwith the round-tripdelaywill still comparefavorablywith the
interactiveresponsetime of the Internet.
For researcherseparatedby long distances,teleconferencingoffers a viable alternativeto travel.
Travel cannotbe justified for short meetingsand informal contactsthat arean essentialpart of a
working team. Existing teleconferencingcapabilitiesvia telephoneare awkward,expensive,and
not suitedfor the transmissionof visual information. Video teleconferencingis limited to only a
few locationsandis inflexible in terms of scheduling and cost. One of the obvious applications of
increased network capability is video teleconferencing using the networking/display capabilities of
desktop workstations. Various computer hardware and software vendors are beginning to demonstrate
desktop solutions running over standard networks (at least between local area workgroups). Apple
Computers, Digital Equipment Corp., IBM, and Microsoft are some of the companies that have
demonstrated capabilities at various computer shows.
While T-3 bandwidth is still required for two-way, high resolution video, several commercial units
can function over T-1 lines using compression techniques. Long haul networks, such as lnternet,
have not been used as yet, because of inadequate bandwidth. The recent emergence of ATM/SONET
promises the ability to handle multiple data types with sufficient bandwidth. Many vendors are
actively working on incorporating ATM hardware in their workstations.
Most, if not all, of the hardware components necessary for multimedia and teleconferencing exist
today. Video equipment manufacturers (such as Tektronix and the Grass Valley Group) provide the
necessary video equipment such as switching equipment, multiplexers, etc. Telecommunications
vendors provide the necessary routing, data conversion, and transmission equipment through proto-
cols such as ATM. The remaining challenge is in the area of operating systems. For example, UNIX
is not well-suited to the requirements of teleconferencing. Although many vendors are working on
new technologies, most are in early stages of development.
The computer vendors provide the ability to control the network and store the data. Unfortunately,
these areas are very poorly integrated currently. Differences in interfaces, data formats, language
and paradigms, and an extreme lack of software hamper efforts to integrate all information transfer
into a single package. Presently, "integrated multimedia" all too often actually means completely
independent subsystems that happen to be in the same room.
Many vendorsareclaiming "multimedia" solutions,suchasSun Microsystems,Silicon Graphics,
NEXT,andApple, but theseareall in early stagesof development.Challengesappearsto be in the
softwareside,whereit hasbeendifficult to provideanapplicationenvironmentto provide thelinks
betweenvariousdata andmediatypes. NeXT is perhapsthe furthest along,but other companies
have significant researchand developmentactivities.
Onepositiveexampleis QuickTimefrom Apple, which is asystemthat is designedto handlevideo
as anotherdata type. Varioustools are provided so that video recordscan be incorporatedinto
otherApple applications,muchasexisting graphsfrom oneapplicationcan becut and pastedinto
otherapplications.If, for example,onerecordeda video teleconference,onecould useQuickTime
to cut and paste the entire record (or appropriatesubsets)into a meetingdocument. Another
researcher could read the document, and then double-click on the video icon to play the video
of the teleconferencing session. This provides an efficient means of transferring information as well
as a method to maintain a database of these video records. QuickTime has recently been adopted
by Silicon Graphics for its future products.
Often voice is inadequate to express an idea, which is why we point to things and use hand gestures.
Often the topic of discussion is either text or graphics residing on a researcher's workstation. The
ability to have multiple workstations sharing the same view of data, with multiple pointing devices
would allow researchers to identify and manipulate the data directly. Several companies have
been conducting research in this area and created prototype systems. US West has developed a
prototype system for distributed medical collaboration. Called the Telemedicine project, it integrates
voice, video, and shared computer applications. All functions are controlled by the user using a
UNIX workstation. Connections are created using a telephone-like model. After the connection is
established, users may speak to each other, view each other via remote camera, and share applications
and computer graphics. Users have control of the remote camera's pan and zoom so they may "look
around". Also, users may place "pointers" on the computer screen to indicate an item of interest
to other viewers.
"7
Summary
As the capabilities of hardware and software improve dramatically in the early 1990s, it will become
possible to achieve "media integration" to support researchers located within academic departments
and research units. With the coupling of these technologies to high bandwidth land and satellite
links, it will be possible to expand this integration to include researchers distributed worldwide.
Such global-scale "enterprises" are essential if we are to make significant progress in understanding
the Earth as a dynamic system. ACTS capabilities can play an important role in these activities.


MODIS algorithm development and data visualization using ACTS

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server