The detection of a newly introduced crop into the Imperial (California) Valley by sequential ERTS-1 imagery is proving that individual crop types can be identified by remote sensing techniques. Initial results have provided an extremely useful product for water agencies. A system for the identification of field conditions enables the production of a statistical summary within two to three days of receipt of the ERTS-1 imagery. The summary indicates the total acreage of producing crops and irrigated planted crops currently demanding water and further indicates freshly plowed fields that will be demanding water in the near future. Relating the field conditions to the crop calendar of the region by means of computer techniques will provide specific crop identification for the 8000 plus fields

Coleman, V. B.

Johnson, C. W.

English

NASA Technical Reports Server

Paper A 2 
SEMI-AUTOMATIC CROP INVENTORY FROM SEQUENTIAL ERTS-1 
IMAGERY 
Claude W. Johnson and Virginia 8. Ccleman, Department of Geography, 
University of California, Riversids, Glifornia 92502 
ABSTRACT 
The detection o f  a newly introduced crop i n t o  the 
Imperial (Cal i forn ia)  Val l ey  by sequential ERTS-1 imagery 
i s  proving tha t  indiv idual  crop types can be i den t i f i ed  by 
remote sensing techniques. I n i t i a l  resu l t s  have provided 
an extremely useful product for water agencies. A sysrem 
f o r  the i den t i f i ca t i on  o f  f i e l d  conditions enables the 
production o f  a s t a t i s t i c a l  sumnary w i th in  two t o  three 
days o f  rece ip t  o f  the ERTS-1 imagery. The sumnary indicates 
the t o ta l  acreage o f  producing crops and i r r i ga ted  planted 
crops current ly  demanding water and fu r ther  i ndf cates f resh ly  
plowed f i e l d s  tha t  w i l l  be demanding water i n  the neap future. 
?elat ing the f i e l d  conditions t o  the crop calendar of the 
region by means o f  computer techniques w i l l  provide spec i f ic  
crop i den t i f i ca t i on  f o r  the 8000 plus f i e lds .  
1. INTRODIJCTION 
A t  the conclusion o f  the f i r s t  named authors repor t  on Crop 
Inventory o f  the Imperial Valley from Apollo I X  i t  was stated tha t  the 
i den t i f i ca t i on  o f  spec i f ic  crops could be great ly  improved over the 60% 
accuracy attained, i f  seqtrential imagery from satel  1 i tes could be ob- 
tained. ERTS-1 has provided such imagery! Each successive image i s  
supplying addi t ional  proof that  i n  the laboratory environment of the 
Imperial Valley automatic crop i den t i f i c s t i on  i s  possible. 
The object ive o f  the current invest igat ion i s  t o  develop a seml- 
automatic system tha t  w i l l  i den t i f y  the spec i f ic  crop being produced 
i n  each o f  the 8000 plus f i e l d s  i n  the Imperlal Valley. Time i s  o f  the 
essence i f  data interpreted from ERTS i s  going t o  be useful t o  the 
water managers, the packers, the shippers, the market special ists,  the 
loan bankers, ad inf inf tum. Therefore, any system must produce resu l t s  
i n  the shortest possible time, and cer ta in ly  no longer than one week 
a f t e r  the ins tant  inventory i s  obtained. 
I n i t i a l  resu l t s  fram ERTS-1 indicate tha t  the data can be 
interpreted, irrlalyzed, and produced w i th in  two t o  three days wi th  less 
than 40 man hours and a few minutes computer time. A "spin off" r e s u l t  
Oiizinal ~ h c t o g r a p h y  may be purchased from: l9 E(. .. ' ' 
,d.) i,'-1:%3 LClli?f 
10;n an3 Dakota Avenue 
SIOUX fails. $3 57198 
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https://ntrs.nasa.gov/search.jsp?R=19730019478 2020-03-17T09:05:18+00:00Z
o f  the procedure provides an imnediate assessment o f  i r r i g a t i o n  demands 
that  w i l l  hold f o r  the en t i r e  18 days between ERTS-1 cycles. 
2. ANALYSIS AND METHODOLOGY 
The system adopted f o r  the research i s  somewhat unique from several 
other types o f  crop i den t i f i ca t i on  systems. It combines the best ta lents  
o f  man and machine t o  produce rapid resu l ts .  More unique i s  the lack o f  
dependence on the v a r i a b i l i t y  o f  the color in f rared response as the 
prime d i f f e ren t i a  t i on  fac tor  between crop types. The system does depend 
upon both: 1 the a b i l i t y  t o  detect  ind iv idua l  f i e l d  condit ions from 
ERTS-1, and I 2 1 the a b i l i t y  t o  r e l a te  sequential f i e l d  condit ions t o  
the regional crop calendar. The key t o  rap id  analysis i n  the current 
study i s  the use o f  the mult i -spectral  response t o  detect only the pres- 
ence or  absence o f  a producing crop i n  a f i e l d .  
The qua l i t y  o f  reso lu t ion from ERTS-1 imagery has proven t o  be 
bet ter  than tha t  experienced wi th  Apollo I X  imagery. Suparimposi t i o n  o f  
the imagery onto a 1 :62,500 scale base map enables the detect1 on o f  f i e l d  
conditions o f  f i e l d s  as small as 10 acres (4 hectares) and a few eben 
smaller 5 acre (2 hectares) p lo ts .  However, because o f  the uncertainty 
o f  detection (or  i den t i f i ca t i on )  o f  a l l  f i e l d s  below 20 acres (8 hectares) 
the project  i s  being l im i t ed  t o  the monitoring o f  f i e l d s  o f  20 acres and 
greater. Less than 2% o f  the t o ta l  farn~able acres are affected by t h i s  
decision. The resolut ion w i l l  permit the f i r s t  dependent c r i t e r i a  of 
indiv idual  f i e l d  detection t o  be met, but  can the f i e l d  condit ion be 
iden t i f i ed?  
The f i r s t  th ing noted on the ERTS-1 imagery o f  the Imperial ?al ley 
was four d i s t i n c t  colors w i th in  the agr fcu l tura l  f i e l d s  - red, purple, 
lavender or brown, and white. Certainly the red from fa lse  color mu1 ti- 
spectral in f rared imagery re la tes t o  vegetation which we can iden t i f y  as 
growing crops. The white color eas i l y  re la tes t o  dry  bare f i e l a s  i n  the 
a r i d  desert climate. The bare f i e l d s  can be e i the r  fa l low f i e l d s  await- 
i ng the next crop ro ta  t l on  or  they can be f ie lds  which have been abandoned 
because o f  uneconomical production due t o  s a l i n i t y  problems. The other 
two colors proved t o  be the t r ans i t i on  a c t i v i t y  from fa l low f i e l d  t o  
producing f i e l d .  The moisture content revealed by a f resh ly  plowed f i e l d  
vroduces a 1 i g h t  brown or lavender ,-dlo: on the ERTS-1 color combined 
image. Likewise, the moisture response o f  a f resh ly  i r r i ga ted  f i e l d  i n  
which the seed har not ]at ggrminated w i l l  produce a deep purple or  dark 
blue response on the co lor  combined ERTS-1 image. The di f ference between 
purple and blue i s  fn  the qua l i t y  control  fac tor  o f  the color combined 
image produced from bands 4, 5, and 7 o f  tha mu1 t i -spect ra l  scanner 
images. The detection o f  four simple colors enables us t o  fo l low the 
farming cycle from f.allow, t o  plowed, t o  i r r i ga ted  seed, t o  growing 
crop, and i n  the case o f  gra in  crops t o  the harvest cycle. The l a t t e r  
case occurs when the maturing crop turns t o  yel iow o r  golden brown c r  
even when only the yel low stubble remalns i n  the f i e l d .  A yel low 
response on the ERTS imagery thus indicates a mature or  harvested gra in  
crop. A co lor  tha t  has not  ye t  occurred I n  Imperi, I Valley, but has 
been seen i n  the Central Valley o f  Cal l f o r n i a  I s  the black resu l t i ng  
from the bur-+ng o f  the gra in  stubble f l e l ds .  Again we have seen tha t  
the detectlon o f  the lnd lv ldua l  f i e l d  condl t lon i s  possible from ERTS 
imagery and our f i r s t  dependent i den t i f i ca t i on  fac tor  can be satisf ied. 
What about r e l a t i ng  the f i e l d  condit ion to  the crop calendar? 
Table 1 re la tes the Imperial Val l ey  Crop Calendar t o  ERTS-1 cycles 
2, 4, 6, and 8. For the purposes o i  computer manlpulatlon the f i v e  
C!eld conditions detectable oc ERTS have been coded 1 f o r  growing crops, 
2 f o r  wet planted f ie lds ,  3 f o r  plowed f le lds ,  4 f o r  bare f l e lds ,  and 
5 f o r  harvested f ie lds .  Reference t o  the specialized calendar indlcates 
how a crop such as sugar beets w i l l  change from bare sol 1 t o  a growlng 
crop over the four 36 day cycles of ERTS-1. A computer program tha t  
w l l l  examlne the cyc l i c  record o f  each 06 the 8000 plus f i e l d s  and 
establ ish the most l i k e l y  spec l f ic  i den t l f l ca t i on  based upon the crop 
calendar I s  presently being wri t ten.  Prevlolrs experience .~i t h  a s im i la r  
type computer program suggests that  93 t o  97% accuracy can be anticipated. 
The use o f  the va r ia t ion  I n  the red hues t o  ass is t  i n  d i f fe ren ta t ion  
o f  crop types has not been completely discarded by the authors, but pre- 
vlous experience has produced serious reservatlons about the effectlveness 
o f  the color var ia t ion factor.  Uncontrollable factors o f  va r ia t ion  are 
introduced fn to  color In f rared imagery by i n i t i a l  f i l m  production, physi- 
ca l  factors occurring a t  the time the Image i s  obtafned, phenelogical 
and maturation factors i n  the vegetation i t s e l f ,  even reproduction 
factors I n  the color combinlng process, and var ia t ions i n  the f i n a l  f l l m  
processfng. T i m  res t ra in ts  have made us decide tha t  we should no t  r e l y  
too heavily on the red color var lat ions f o r  crop i den t l f l ca t l on  a t  t h i s  
time. 
The current t iming f o r  production o f  s t a t i s t i c s  f o r  one ERTS-1 cycle 
I s  5-6 hours o f  f i e l d  co i~d l t i on  In terpreta t ion from a superlmposed image 
onto the base map. Approximately 25-30 hours o f  coding and keypunching 
the data from the base map t o  computer cards are requlred. To complete 
the s t a t l s t l c a l  sumnarles s h a n  i n  Table 2 about 30 seconds o f  IBM 360 
computrr time I s  required. 
3. RESULTS 
The detectlon on the December 12 (cycle 8) ERTS-1 Imagery of a 
newly introduced crop i n t o  the Imperial Valley and subsequent reference 
t o  previous sequential Imagery provides strong indlcat lons tha t  the crop 
calertdar system w l l l  be successful. On the December Image e lgh t  f l e l d s  
totalt!ng 900 acres (364 hectares) appeared as a very d i s t l nc t l ve  orange- 
yellow. Located tn the northeast area o f  the valley, t o  the east of 
Wlest Lake, the f l e l d  condlt lons d l d  not  f l t  the crop calendar pattern 
f o r  a harvested crop. These f l e l d s  then became the f i r s t  crops that  
d i d  not f l t  I n to  the 97% Iden t i f i ab le  category. Reference t o  the 1972 
Crop Report o f  the Imperial I r r l g a t l o n  D l s t r l c t  revealed a new crop 
under productlon. I n  1971 80 acres (32 hectares) o f  a new crop (A l l c l a  
Grass) was tested. I n  1972 over 1000 acres (405 hectares) o f  A l l c l a  
Grass was planted. A l l c l a  Grass i s  a va r ie ty  o f  Bermuda Grass and I s  
grown t o  provlde a high prote ln  f resh hay tha t  w l l l  produce I n  mld- 
wlnter. The calendar f o r  A l i c i a  Grass indicates tha t  It should be 
ready f o r  harvest I n  mid-December and w l l l  thus provlde the only yel low 
response f o r  t h l s  time o f  year I n  the Imperial Valley. 
Table 2 sumnarlzes the s t a t l s t l c a l  l lspln-off" generated by the 
Invest lgat lon t o  date. The 460,000 farmable acres ,186,155 hectares) 
can eas i l y  be monl tored f o r  f l e l d  condl t lons as previously d e w 1  bed. 
The decl lne o f  growlng crop acreage from 33% down t o  312 I n  the ear l y  
f a l l  I s  t o  be anticipated. Unlike many other areas of the Unlted States 
the crop productlon beglns t o  increase I n  November (43%) and w i l l  bs 
expected t o  r4se t o  a peak I n  l a t e  March o r  ea r l y  A y l l .  The cycl  l c  
demands f o r  i r r i g a t i o n  water can be read i l y  determlned by both Immediate 
crop demands and fu ture needs. Future needs are Indicate? by the 
f resh ly  plowed f ie lds .  Coxlpletlon o f  the I n i t i a l  phase of the ERTS-1 
pro ject  w i l l  provlde the State Water a,zncy and the Imperial I r r l g a t l o n  
O l s t r l c t  6 bery d e f l n l t l v e  cyc l i c  record o f  water demand throughout the 
year. 
4. CONCLUSION 
The a b l l l t y  t o  detect and I den t i f y  lnd lv idua l  f i e l d  condit ion has been 
proven without question. The a b l l l t y  t o  automatically re l a te  thc f l e l d  
c o n d l t l ~ r ~ s  t o the crop calendar remains t o  be determlned. The compllatlon 
o f  f l e l a  condl t l o n  data frcm four 36 day cycles f r o m  ERTS-1 p r c ~ f d e s  the 
necessary Input t o  t e s t  a computer program tha t  w l l l  examine each of 
these cycles f o r  each o f  the 8000 plus lndlv ldual  f l e l ds  and pred ic t  
what crop each o f  the f l e l d s  I s  produclng. The remalnlng months of the 
c o ~ t r a c t  w l l l  be devoted t o  the completlon and tes t lng  o f  the computer 
program. 
Figure 1. ERTS-1 December 12. 1972 YSS Band 5 inage of Imperial 
tilley. Dark f i e l d s  are grawing crops. Note the l ack  o f  growth 
In the Mexicalli :'alley i n  0 a j a  Calffornla a t  t h i s  tlme o f  year. 
TABLE 1 
IWEilIAL VALLEY CROP WEmlcrR FOR ERTS-i DETECTEJ FIELD CWDITIONS 
CROP TYPE 
FIELD CROPS 
L r l r y  (Pasture) 
L r l o y  (Grain) 
Sorghum 
OIts 
What  
Pam (6ralq) 
Grass ( Ikmdr  6 A l l c l a )  
~ N S S  (@) 
Grass (Sudan) 
A1 fa1  f a  
Sugar Beets 
Cotton 
Raw 
VEGETABLE CROPS 
Lat tucr  
ktPrd 
Cabbrgc 
Clntr loupa (Fa1 1 )  
C t n t r l w p a  (Sprlng) 
';cumbars (Fa1 1 ) 
Cucunbrrs (Sprlng) 
Watanmlon 
Tonr t o t s  
Carrots 
Onlons (Bunching) 
Onlons (Dry) 
Squash (Sunmmr) 
FIELD CONDITION CODE BY DATE 
AWiUn 26 OCTCBER 1 IKIVEIISER 6 DECEmER 12 
(FIELD CONDITION CODE LEGEND: 1- Rod) growln cr lps;  2-(Purplc) mt sol1 s a d d  cro s; 
3- I Lavandar) Vnnd r o l l ;  4 - ( ~ i t a )  *re s o i l ;  5 - ( h 1  ow) 
h a r v r s t d  stulb'ia) ! 
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Semi-automatic crop inventory from sequential ERTS-1 imagery

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