The management of NASA earth observation data is discussed. User requirements are identified, as well as means to facilitate data acquisition. It is shown that LANDSAT data can be preprocessed to condense data into a more accessible format, thus reducing data acquisition costs

Mcdonough, G. F.

English

NASA Technical Reports Server

DATA ~ANAGEMENT FOR EARTH OBSERVATIONS 
George F. McDonough 
Deputy Director, Data Systems Laboratory 
George C. Marshall Space Flight Center 
Marshall Space Flight Center, Alabama 35812 
201 
https://ntrs.nasa.gov/search.jsp?R=19770023346 2020-03-20T07:53:15+00:00Z
The Earth Observations efforts of NASA and other Federal agencies have 
matured into near-operational programs which require large amounts of data on 
a time-constrained basis. To meet these needs considerable efforts have been 
undertaken by the agencies as well as by users of the data. Potential problems 
are discussed along with an approach to reducing costs and providing needed 
information. User  participation in the process of data management is one key 
to its success. Some available means for the user to become involved are 
considered. 
With increasing maturity of the acquisition systems for remote sensing, 
especially the weather and Earth resources satellites such as Nimbus and Land- 
sat, emphasis has shifted toward the application of the data from these satellites. 
For example, the extensive use of Landsat data for a wide variety of applications 
has established the utility of this kind of remotely sensed data (Fig. 1). A s  a 
consequence, emphasis is shifting beyond initial utilization and approaching the 
operational use of remote sensing data. By operational use is meant the day-to- 
day use of remotely sensed data as a part of the process of decision making 
regarding natural resources, for example. A s  the applications of such data 
increase, so do the requirements for management of the data, which is the 
subject of this presentation. 
BASIC REMOTE SENSING SCIENCE IS MATURE 
- SIGNATURES 
- APPLICATIONS 
EMPHASIS SHIFTING TO OPERATIONAL SYSTEMS 
- AUTOMATED PROCESSES 
- MULTIPLE SYSTEM INTERACTIONS 
- TIMELINESS 
- COST 
0 UTILIZATION BY PUBLIC BROADENING 
-WEATHER 
- MAPPING 
Figure 1. Evaluation of data situation. 
In each of the areas presented in Figure 2, there is substantial effort 
underway to establish the required systems, technology, and analysis techniques 
to meet the data management needs of the 1980's and beyond. 
202 
AGRICULTURE 
- INVENTORY 
- CROP FORECASTING 
0 WEATHER 
- GLOBAL MARINE 
- SEVERE STORMS 
0 WATER AVAI LAB1 LlTY 
POLLUTION MONITORING 
LANDUSE 
Figure 2. Some areas of major data system emphasis. 
Taking Global Marine Weather as an example, a substantial number of 
users can be identified. Some of the more important users are listed in Figure 3. 
The Navy and Coast Guard are served by DoD weather programs, fishing fleets, 
oil companies (off-shore rigs),  etc., a r e  served by the weather programs 
included under the "Local and Large Scale Weather" programs. Commercial 
shipping companies, which range worldwide, currently have potential require- 
ments beyond the goals of these programs. 
0 US. NAVY 
0 U.S. COAST GUARD 
0 FISHING FLEETS 
0 OIL COMPANIES 
DoD WEATHER PROGRAMS 
I 
0 COASTAL CITIES 
0 RECREATION ACTIVITIES I LOCAL AND LARGE SCALE WEATHER I I 0 WEATHER RESEARCHERS 0 COMMERCIAL SHIPPING COMPANIES 
Figure 3. Users of marine weather infbrmation. 
Figure 4 shows requirements for a Global Marine Weather forecasting 
system which measures temperatures, winds, etc, , by means of instrumented 
buoys, stations, ships, and satellites. The data are inputs to an analysis and 
prediction model which produce 1, 3, and 15 day forecasts. A 1 day forecast 
is produced in 12 h from acquisition, a 3 day forecast in 24 h, and a 15 day 
forecast in 3 days. 
20 3 
ATMOSPH E RE 
WATER 
TEMPERATURE PROFILES 1°C 
WINDS f 3 m h  
PRESSURE f 0.3% 
RELATIVE HUMIDITY f 30% 
ICE FLOWS, LEADS 100 m 
h 
3 DAYS 
TEMPERATURE 
PRECIPITATION 
SEA STAT€ 
ICING AND STORM CONDITIONS 
WITH ACCURACIES OF 95, 75 
AND 50% 
Figure 4. Functional system requirement. 
The flow of data for the Navy system is shown in Figure 5. Satellites 
such as Nimbus, which service the National Weather Service (NOAA) system 
supplement the military acquisition systems. Seasat A ,  currently under develop- 
ment by NASA, also will feed data to the system in the 1980's. Fleet Numerical 
Weather Central possesses the models to transform these data into forecasts 
which a re  fed back to NOAA and also, through Fleet Weather Centers (FWC) to 
ships at sea. Information also is supplied to commercial forecasting companies 
who, in turn, supply it to commercial shipping and other users. 
Data management often is perceived as a problem both by originators 
and/or suppliers and by users, largely because of the potential for high costs, 
delays, and other detrimental results which can occur if data management is 
not properly used (Fig. 6 ) .  The Global Marine Weather situation shows the 
complexity of interfaces a s  well a s  the use of multiple data sources. Many of 
the sensors used a re  capable of acquiring data at high rates (megabits per 
second) which could lead to high costs. 
204 
,,-,,,J COMMERCIAL 
POSSIBLE EFFECTIVE FORECASTING 
UTlLlZATlON AFTER 1980 
SHIPS 
STATIONS 
Figure 5. Data flow for the Navy system. 
0 HIGH DATA RATES 
0 MULTIPLE DATA SOURCES 
- MULTIPLE SPACECRAFT 
- AIRCRAFT 
- GROUND DATA COLLECTION 
- ANCILLARY DATA 
8 PROCESSING, HANDLING, AND STORAGE COSTS 
Figure 6. The data management problem. 
To establish what the possible data acquisition rates mean, Figure 7 
shows the meaning of loi5 bits/year ( a  bit is the basic element of input to a 
computer which represents essentially the basic, or  smallest, element of data). 
This amount of data can be acquired by the sensors under planning for the 
1980's. Roughly it equals 10 times all the data acquired for whatever purpose 
in the year 1972. If NASA were to process these data using our Skylab system, 
which was a substantial one, it would take 100 years. 
205 
VO LUM E : 
1015 BITSNEAR 
100 LIBRARIES OF CONGRESS 
100 MILLION SEARS CATALOGS 
10 DATA TOTALS FOR 1972 
30 ERTS-1 
PROCESSING TIME: 
100 YEARS AT SKYLAB RATES 
Figure 7. Significance of estimated yearly data 
output for the 1980's. 
This problem can be solved either by vastly increasing our capacity to 
process and handle data or  by reducing acquisition to match information needs 
(Fig. 8). Clearly, reducing acquisition is preferable, and using this approach 
does not prevent improving or  adding capabilities where required. It does 
present the problem of understanding the use to which the data a re  being put 
well enough to judge what data a re  required. This involves intimate association 
with the user and his application. 
TWO APPROACHES SHOW PROMISE FOR SOLUTION: 
1. INCREASE THROUGHPUT TO MATCH SENSOR CAPABlLlTIES 
0 OPTIMIZE UTILIZATION OF FACILITIES 
0 ADD FACILITIES 
0 ADVANCE STATE-OF-THE-ART: IMPROVE FACILITIES 
2. REDUCE ACQUlSlTlON TO MATCH INFORMATlON REQUIREMENTS 
ADVANTAGES OF REDUCED ACQUISITION 
0 MOST EFFECTIVE WAY TO REDUCE COSTS 
0 IMPROVES EFFICIENCY OF INFORMATION APPLICATION 
Figure 8. Approaches to problem solution. 
The user also has problems with remote sensed data since some of the 
handling and processing is his responsibility and since the ultimate application 
is his job (Fig. 9). If data can be put into formats similar to those of the 
products with which he normally works, his problems can be diminished 
appreciably. H e  must be informed a s  to availability and location of data before 
he can use the data, and he must understand automated retrieval systems if that 
is his only access to the data. This requires extensive training and familiarization. 
206 
WHY IS REMOTE SENSING DATA A PROBLEM TO THE USER? 
0 UNFAMILIAR FORMATS 
0 CHANGES IN ESTABLISHED PROCEDURES 
0 LACK OF INFORMATION ON WHAT I S  AVAILABLE AND WHERE 
0 DATA INVOLVES HIGH TECHNOLOGY 
0 TRAINING/FAMILIARIZATlON REQUIRED 
0 COSTS OF PROCESSING 
Figure 9. The data management problem. 
The NASA approach to data management includes, in addition to technology 
development and selectivity, concepts of end-to-end optimization of data systems - 
from sensor to user, coupled with an early consideration of data problems ( Fig. 
10). Too often data problems are  considered only after acquisition systems and 
other major elements of the data system have been defined. This limits the 
gains to be made from efficient data management. 
0 EARLY CONSIDERATION OF DATA PROBLEMS 
0 END-TO-END QPTlMIZATlQN 
e COMPRESSION 
0 TECHNOLOGY DEVELOPMENT 
0 SELECTIVITY 
- HIGH INFORMATION/DATA RATIO 
- CAREFUL TAILORING TO USER NEEDS 
- UTILIZATION OF USER KNOWLEDGE 
Figure 10. An approach to data management. 
Some potential reductions in data processing requirements are  given in 
Table 1, The reductions are  based on knowing enough about the application to 
judge what is required to solve the problem. For example, Landsat acquires 
data over the test site every 18 days or  approximately 20 times per year, but 
the application, in this case landcover analysis, only requires two images per 
year. Similarly two spectral channels are  sufficient, although four a re  available 
and the test site covers only a small portion of the 100 x 100 n.mi. image. 
Finally, data compression techniques can further reduce the throughput until 
total reduction is from 9000: 1 to 60 000: 1. Even greater decreases a re  feasible, 
a s  will be seen, so that it will be possible to handle all the required data in an 
affordable way. 
207 
- 
m 
\ rn 
yI_u 
t 
208 
A further development of data compression, based on work at the Jet 
Propulsion Laboratories shows promise of reductions of more than 3000: 1. It 
involves the preprocessing of Landsat data in a 17black-boxT7 to reduce the effort 
done by the user. Cost savings to the user are shown in Figure 11. Savings 
such as these can make remotely sensed satellite data very competitive with 
other types of data. 
LANDSAT DATA FEATURE VECTOR REDUCTION 
2048 DIFFERENT 
FEATURE VECTORS 
- 
7,581,600 pelt + 
SUPPLY DATA 
TO USER 
CLASSlFY (8) 
(ELLTAB) 
9185 wc 
2.55 h 
$892.50 
LINEAR 
STRETCH 
2277 rec 
38 min 
$221.37 
7,581,600 pelt 
SUPPLY DATA 
TO USER 
CLASSIFY (8) LINEAR 
(E LLTAB) STRETCH 
2.5 sec 0.6 tec 
M.24 $0.05 
Figure 11. U s e r  cost savings. 
Users have access to considerable help from NASA, as well as other 
agencies such as USDA who utilize remotely sensed data in their activities 
(Fig. 12). This help is available through the Technology Utilization Office 
and other channels, Universities and industry participating in NASA remote 
sensing and data management programs also can provide help. 
One of the tools available to users is the Data Systems Dynamic Simu- 
lator at MSFC, which enables users and data systems designers to evaluate 
alternate methods of handling and processing data ( Fig. 13). It also serves 
as  a training and familiarization device for users who are  not knowledgeable 
of Earth resources data systems. 
, 
209 
e DOCUMENTS DESCRIBING 
- DATA SYSTEMS 
- AVAILABLE DATA AND APPLICATIONS 
e COMPUTER - INTERACTIVE ANALYSIS CONSOLES 
e SIMULATIONS 
e DATA BASES 
- AVAILABLE IMAGERY 
- DATA SYSTEM TECHNOLOGY 
0 TRAINING 
Figure 12. Some available tools to help the user. 
Figure 13. Data Systems Dynamic Simulator at MSFC. 
21 0 


Data management for earth observations

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