State planners are increasingly becoming interested in ERTS as a possible method for acquiring land use data. An important consideration to them is whether ERTS can provide such data at a savings in both time and money over alternative systems. A preliminary evaluation of ERTS as a planning tool is given

Goldstein, W. D.

Lindgren, D. T.

Simpson, R. B.

English

NASA Technical Reports Server

Paper L 5 
EVALUATION OF ERTS-1 DATA FOR ACQUIRING LAND USE DATA OF 
NORTHERN MEGALOPOLIS 
Robert 6. Simpson, David T. Lindgren and William D. Goldstein, Dertmouit, Cd/ege Pmject in 
Remote Sensing, Hanover, N.H. 
BSTRACT 
State planners are increasingly becoming interested in ERTS as 
a possible method for acquiring land use data. 
consideration to them is whether ERTS can provide such data at 
a savings in both time and money over alternative systems. 
following is a preliminary evaluation of ERTS as a planning tool. 
An important 
The 
INTRODUCTION 
Among the investigations funded by NASA under the WTS-1 Program was one 
for the investigation of the land use of northern Megalopolis by the Dart- 
mouth College Project in Remote Sensing. Specifically the objectives of 
this investigation were (1) to map and digitize the land use of the northern 
third of Megalopolis, and (2) to evaluate ERTS as a planning tool. 
present we have completed the mapping and digitizing phase of the project; 
the evaluation of ERTS as a planning tool is in progress. 
For aid in orientation, a map sharing the Boston-Washington Megalopolis 
among the urban concentrations of the United States has been included (Fig. l), 
as well as a map displaying the location and boundaries of the test area 
(Fig. 2). 
Mapping the Land Use of Northern Megalopolis 
The Color-Coded Version. 
provided the first fully useful imagery of our test area. 
parencies of the four necessary scenes became available from the NDPFC on 18 
December 1972, and the General Electric Photo Laboratory in Beltsville, 
Maryland, provided the essential unenhanced 1:250,000 CIR transparencies of 
those scenes on 3 January 1973. 
photointerpreter completed the three-state land use map in draft form within 
three months (1 April 1973). 
to complete the final color-coded map (Fig. 3 ) .  Thus, it took five months to 
complete the map by conventional photointerpretation techniques. 
because of a variety of constraints we did not use multi-seasonal coverage, 
we relied exclusively on MSS bulk-processed products, and we made infrequent use 
of the individual bands. 
At 
Good weather over New England in mid-October 1972 
Nine-by-nine trans- 
Working from the CIR transparencies a single 
However, it took another two months (1 June 1973) 
Furthermore, 
371 
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NEW ENGLAND TEST SITE 
p P A R T  OF SITE COVERED 
IN THIS INVESTIGATION 
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Figure  2. The T e s t  A r e a .  --- 
373 
Computer Version. I n  the  course of this invest igat ion the DCPRS has developed 
an in t e rac t ive  time-sharing system which not only produces f i n e  q u a l i t y  com- 
puter graphics (Fig. 4) but a l s o  is capable of e f f i c i e n t l y  manipulating l a rge  
data bases ( i n  t h i s  case over 600,000 data  c e l l s ) .  Land use data  were input 
d i r e c t l y  i n t o  the computer on a cell-by-cell bas i s  using free-format disc- 
storage f i l e s ,  by typing the majority land use f o r  each 114 square kilometer 
(62 acres)  c e l l .  Subsequently, these f i l e s  w e r e  transformed under program 
control  t o  the true-to-scale data  base. 
On the bas i s  of these data  i t  is  possible  t o  receive within t h i r t y  minutes 
real time and but a few minutes computer t i m e ,  a map of the test si te which 
v i sua l ly  h igh l igh t s  any s i n g l e  use o r  combination of uses i n  a form less v i s u a l l y  
complex than the  multi-colored maps, and a l s o  a f i l e  on the land use summary 
tabulations formatted t o  be compatible with the Dartmouth System's c o r r e l l a t i o n ,  
regression, and c lus t e r ing  routines.  Perhaps the g r e a t e s t ,  but as y e t  untapped, 
asset  of t h i s  system i s  its appl icat ion t o  land use change detect ion invest i -  
gations. 
Comparability, Cost and Time Effectiveness.  
Comparability. The s ta te  of Connecticut i s  unquestionably one of the na t iona l  
leaders i n  the qua l i t y  and completeness of i ts land use data.  J u s t  this year 
a f t e r  three years of preparation a new land use map w a s  published a t  a cos t  of 
more than a mil l ion dol lars .  
of a scale 1:12,000, t h a t  i s ,  almost 90 t i m e s  l a r g e r  than ERTS. The r e s u l t a n t  
map was of a scale 1:24,000 and contained 55 categories  of land use. 
A t  t h e  same t i m e  a small-scale version of t h i s  map was published (1:250,000) 
on which the  55 categories of land use had been aggregated i n t o  eleven, thus 
corresponding c lose ly  t o  the  ERTS map (Fig. 5).  While it  i s  u n r e a l i s t i c  t o  
expect the two products t o  provide highly similar r e s u l t s ,  i t  does provide an 
opportunity t o  a t  least v i sua l ly  examine the v a l i d i t y  of t he  ERTS map. 
Cost and Time Effectiveness.  
map could be made from ERTS-1 imagery i t  would be a t  a savings i n  t i m e  and money 
over other  means of production. The completion of the th ree - s t a t e  ERTS map 
makes i t  possible  t o  test  t h i s  assumption. In  the  evaluation which follows, the 
cost  of land-use mapping from ERTS i s  compared t o  t h a t  from high-al t i tude air- 
c r a f t  (RB-57 and U-2, s ca l e  1:100,000) and from medium-altitude a i r c r a f t  
(scale  1:20,000). 
This map w a s  compiled from low-altitude photos 
We have assumed t h a t  i f  a meaningful land use 
The ERTS-1 f igu res  have been derived from the present i nves t iga t ion ,  which has 
involved mapping approximately 15,000 square m i l e s  of southern New England a t  
a scale  of 1:250,000 from a s i n g l e  set of C I R  transparencies prepared by photo 
laboratory processes only. The high a l t i t u d e  f igu res  w e r e  a l s o  derived from 
the experience of the Dartmouth College P ro jec t  i n  Remote Sensing i n  the  inves t i -  
a t i ve  mapping of land use i n  the Boston and New Haven areas (Approximate 1,500 
square miles) using NASA RB-57 photography under USGS/GAP con t rac t  i n  1970-71. 
374 
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Fig. 5 Comparison of Connecticut Land Use Map with ERTS 
377 
Fig. 6 
Estimates of Comparative 
Cost- and Time-Efficiency i n  Land U s e  
Mapping 
(a)  (b 1 (C) (d) - c o s t  T i m e  Scale  of S t a t u s  
Imagery 
($/sq.mi.) ( r a t i o )  ( i n t e r p . h r s /  
1000 sq.mi.) ( r a t i o )  ( r a t i o )  
ERTS-1 $ 1.06' 1: 455 1: 1:1,000,000 1: Experimental 
High-altitude 
a i r c r a f t  10.462 10: ' 3286 7 :  1:100,000 10:  Experimental 
Medium-a1 t i t u d e  
a i r c r a f t  15.50 15: 1,3807 31: 1:20,000 50: Opera t iona l  
(23.80) (22:) 
Assumptions : 
* Product is  a numerical ly  coded b/w, o r  rough color-coded, map wi th  
11 ca tegor i e s  of land use 
* Costs and t i m e  shown a r e  f o r  imagery i n t e r p r e t a t i o n  phase only 
(no charge f o r  imagery) 
* Bases f o r  i nd iv idua l  d e r i v a t i o n s  are shown i n  the  foo tno te s  which 
follow 
Footnotes : 
Basis: This  f i g u r e  r ep resen t s  an approximation of DCPRS experience i n  
experimental ly  mapping t h r e e  southern states of New England (14,371 s q .  mi.) 
under NASA con t r ac t  i n  1973 as fol lows:  
Photo i n t e r p r e t e r ,  4 months, i nc lud ing  d i r e c t ,  f r i n g e  and i n d i r e c t  
cos t s ;  commercial photo l ab  s p e c i a l  f i l m  process ing  and en la rg ing ;  
f i e l d  check and ground t r u t h ;  and management inc luding  d i r e c t ,  
f r i n g e  and i n d i r e c t )  
To ta l  $ 15,300 
Average c o s t  of $ 1.06/sq. m i .  
3 78 
Basis: based on DCPRS experience i n  experimentally mapping the 
Boston area (1,100 sq. mi.) under USGS contract  i n  1970. 
Photo in te rpre te r  t i m e  reduced from 1 2  t o  9 weeks due t o  reduction 
of categories mapped from 24 t o  11, and elimination of extensive hand 
coloring. 
Total  $ 11,506 
Average cos t  of $10.46 sq. m i .  
- Basis: cost  estimates received from three commercial mapping agencies, 
f o r  mapping an area s imi la r  t o  s t a t e  of Connecticut (5,000 sq. mi.) 
Average of the  3 was $15.50 per sq. m i .  ( f o r  in te rpre ta t ion  
and map making only) 
Basis : t h i s  f igure  represents $15.50 plus  $8.30/sq. m i .  f o r  photography 
the average of pr ices  submitted be the  3 c0mpanie.s. 
Basis: same as f o r  footnote (1) 
14,371 sa. m i .  i n  4 months (640 hrs . )  of i n t e r p r e t a t i o n  time - x -  ~~ ~ . -
Average of 45 hrs .  i t e rpre ta t j  Lon per 1,000 sq. m i .  
r r . - - L _  I.- Basis: same as f o r  roocnoce ( 2 )  
1,100 sq. m i .  i n  9 weeks (360 hrs . )  of i n t e r p r e t a t i o n  t i m e  
Average of 328 hours in te rpre ta t ion  per 1,000 sq. m i .  
Basis: Average of the t i m e  estimates received from the three  contractors  
re fer red  t o  i n  footnote (3) above 
1,000 sq.  m i .  i n  1,380 hrs.  in te rpre ta t ion  t i m e  
Average of 1,380 hrs .  in te rpre ta t ion  per 1,000 sq. m i .  
379 
The lower (medium-altitude) a i r c r a f t  f i g u r e s  r ep resen t  t h e  numerical averages 
of es t imates  provided by t h r e e  commercial a i r -photo .  mapping organiza t ions  
with ex tens ive  experience i n  Northeastern United States. 
I n  each case  pure ly  human - v i s u a l  image i n t e r p r e t a t i o n  is  assumed using con- 
vent iona l  photo l abora to ry  products .  
r ead i ly  a v a i l a b l e  publ ished ground t r u t h  would be used ex tens ive ly .  
F ie ld  checking would be l i m i t e d ,  but  
Column (a)  shows t h a t  t h e  image i n t e r p r e t a t i o n  phase of land  use mapping can 
be done from ERTS f o r  about $ l / sq .  m i .  i n  comparison wi th  approximately 
$lO/sq. m i .  from h igh-a l t i t ude  a i r c r a f t  and $15/sq. m i .  from medium-altitude 
a i r c r a f t .  The la t te r  estimate maybe more conserva t ive  than the o t h e r  two 
s ince  i t  i s  based upon competi t ive commercial experience r a t h e r  than on i n v e s t i -  
ga t ive  research  programs. 
Column (b) r evea l s  a g r e a t e r  spread i n  time-in-work estimates than i n  do l l a r -  
cos t  estimates. 
p r e t a t i o n  as i n  7 days of U-2 o r  RB-57 i n t e r p r e t a t i o n  o r  i n  31 days of con- 
vent iona l  photo mapping. 
A s  much area can be mapped i n  one day of ERTS land use i n t e r -  
I n  summary, t hese  f i g u r e s  have been compiled from experience probably as extens ive  
as i s  y e t  a v a i l a b l e  i n  t h e  ERTS program, but  i t  is reg iona l  experience and the  
f igures  should be r ev i sed  as n a t i o n a l  experience accrues .  
Conclusions and Recommendations. 
On the b a s i s  of our research  w e  have concluded t h a t  i t  i s  completely p r a c t i c a l  
t o  compile an 11-category land use map f o r  a s ta te  o r  group of s t a t e s  u t i l i z i n g  
unenhanced ERTS-1 imagery and convent ional  manual pho to in t e rp re t a t ion  techniques.  
Furthermore, t he  savings i n  both d o l l a r s  and t i m e  us ing ERTS as opposed t o  air- 
c r a f t  a r e  w order  of magnitude more. 
W e  have a l s o  concluded t h a t  t he  manual read-in by g r i d  c e l l  provides  planning 
o f f i c e s  wi th  a r ap id  and inexpensive method of convert ing a manually - compiled 
land use map t o  a much more broadly u s e f u l  and f l e x i b l e  d a t a  base. 
l ikewise found continued use r  i n t e r e s t  i n  t h e  t r a d i t i o n a l  color-coded land use 
map. 
W e  have 
Our prel iminary eva lua t ion  of ERTS' u t i l i t y  t o  p lanners  sugges ts  almost open- 
ended c a p a b i l i t i e s  f o r  t h e  fu tu re .  I n i t i a l  conferences wi th  p lanners  i n  s e v e r a l  
of the New England states have revealed a near  unanimity i n  i n t e r e s t  i n  ERTS as 
a source of land use da ta .  
p ropor t iona l  t o  the  q u a l i t y  and d e t a i l  of t he  land use information which they 
a l ready  have a t  t h e i r  d i sposa l .  For example, those  states which have very  
de t a i l ed  maps and s ta t is t ics  perce ive  ERTS-1 i n  i t s  p resen t  form a s  a t o o l  of 
l imi ted  va lue  al though they see g r e a t  p o s s i b i l i t i e s  i n  the  e a r t h  resources  
satel l i te  concept - i n  a platform wi th  t h e  performance c a p a b i l i t i e s  proposed 
f o r  EOS, f o r  example. On the  o t h e r  hand, those  states possess ing  l i t t l e  c u r r e n t  
land use information can v i s u a l i z e  an immediate u t i l i t y  f o r  ERTS-1 da t a .  
However, t h e i r  degree of enthusiasm appears  i n v e r s e l y  
380 
ould c e r t a i n l y  be pointed ou t ,  however, t h a t  b o t h  types of states are 
ving any f i n a l  judgement on ERTS u n t i l  f u r t h e r  s ta t is t ical  eva lua t ion  
een completed. To t h a t  end we expect t o  make an  eva lua t ion  of the 
acy of our ERTS-1 land  use  da t a  using land  use  d a t a  acquired by t h e  
c t i c u t  Of f i ce  of S t a t e  Planning as a base. 
rch,  p a r t i c u l a r l y  i n  land use ,  has been conducted i n  t h e  semi-arid West 
umid Northeast  w i th  i t s  smaller p a r c e l  s izes ,  i t s  complex physiographic  
Since much of  t he  ERTS * 
landscapes are more homogeneous and pa rce l  s i z e s  l a r g e r ,  we feel t h a t  
and c u l t u r a l  landscapes,  and i t s  heavier  populat ion d e n s i t i e s ,  provides  a 
b e t t e r  test of ERTS' land use c a p a b i l i t i e s .  
states, e s p e c i a l l y  i n  New England, a l s o  g ives  u s  an  oppor tuni ty  t o  work with 
a v a r i e t y  of land use phi losophies  and planning organiza t ions .  
The smaller s i z e  of e a s t e r n  
I n  t h e  remainj CS-1 r e sea rch  w e  of t h e  Dartmouth College 
P ro jec t  i n  Ren more e f f e c t i v e l y  eva lua te  ERTS i n  terms of 
planners  needs 2 gathered land use  d a t a  and prepared maps 
which we are tak ing  t o  planners  f o r  t h e i r  eva lua t ion .  Under ERTS-B i t  i s  
proposed t h a t  t h e  p lanners ,  i n  t h i s  case from the New Hampshire Off ice  of 
Comprehensive Planning, work w i t h  us  from the very s tar t ,  and that the eva lua t ion  
take  p l ace  cont inuously as we compile from ERTS a s i n g l e  comprehensive state 
land use map f o r  New Hampshire u t i l i z i n g  t h e  l a t e s t  and most e f f i c i e n t  techniques.  
This  map w i l l  be  compiled wi th  New Hampshire on a cost-shar ing b a s i s  and when 
completed should 'enable  us  t o  provide t h e  most pene t r a t ing  eva lua t ion  of ERTS 
from a land use  planning viewpoint y e t  undertaken. 
F ina l ly ,  we are eage r ly  looking f o r  progress  towards a t r u e  second genera t ion  
e a r t h  resources  satellite. The 10-meter r e so lu t ion  proposal  f o r  EOS should 
provide us  wi th  a t r u l y  e f f e c t i v e  land use mapping too l .  


Evaluation of ERTS-1 data for acquiring land use data of northern Megalopolis

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