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Manderscheid, L. V.

English

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E 7.4 - 1 0. 25 3
i ole interest of early and wide dis-
eftination of Earth Resources Survey
Progra information and without liability
for any use made thereof."
INVESTIGATION OF SKYLAB DATA
EREP No. 472-2
December 1973
NASA 9-13332
(74-10253) INVESGATION O SK DATA N74-16014
Monthly Plans and Proqress Report, Dec.N-160
193 (Michiqan State OUniv.) 3 p HC
CSCL 05B Unclas
G3/13 00253
Principal Investigations Management Office
Lyndon B. Johnson Space Center
Ryborn R. Kirby
Lester V. Manderscheid
Michigan State University
Monthly Plans and Progress Report
https://ntrs.nasa.gov/search.jsp?R=19740007901 2020-03-23T12:40:43+00:00Z
*1
Contract NAS 9-13332
Monthly Plans and Progress Keport
December 1973
Eight se.c ;ins in Leroy Township, Ingham Co., wre iused an a sample for
testing the accuracv of photointerpretation an acreva esti lation from the
June 12, 1973 SL-1 imagery. The interpretation for ti ee tests was performed
by a technician. This technician has had experience in photointerpretation
approximately equivalent to that which a user agency might achieve after a year
of training their own technicians. The interpretations were done under approx.
20X magnification with a B&L Zoom 240 stereoscope mounted on a Richards light
table. The technician was given essentially complete freedom in developing his
own tonal signatures for the categories. Tests were conducted using both the
color and color IR imagery. Since first-look interpretive efforts substantiated
the separability to be expected from the general phenology, only three categories
were use!: bare soil; forest; grass, forage crops, and small grains.
The results of these tests are shown in table i and table 2.
Table 1. Results of photointerpretive tests on eight sections in Leroy Twp.,
Ingham Co., Mich. -- Acreage.
Category Color IR Color Ground truth
bare soil 1,112 1,039 1,422
forest 1,265 654 858
grass, forage, grain 1,539 11529 2,002
Totals 3,916 3,222 4,282
Table 2. Results of photointerpretive tests on eight sections in Leroy Twp.,
Ingham Co., Mich. -- % Error.
Category Color IR Color
bare soil -22% -27%
forest +47% 24%
grass, forage, grain -23% -24%
Totals -9% -25%
2In all cases except the forest category interT.:reced from CIR, there was a
consistent underestimation of approximately 25%. Upon further investigation of
the anoaly involving forests as interpreted from .color IR, it was discoveredthat the technician was actually using a wetland signaturc for forests. The
confusion aro,-se because many of the forests in the area are lowland hardwoods.
On the whole, the color film was judged to be more easily interpretable for
most categories than the color IR.
!i : the teiiency toward underestimation, a r:tio :crrectcn fac r seems
to be in order. 11 the ratio correction of 1.25 i, ipli d to che interprctations
from the ):olor f iJn, the results are shown in tabi
fable 3. Results )f photointerpretive tests on eilcht sections in Leroy Two.,
!ingha~ (o., tlich. using color film and a ratio :orrectiIon factor of 1.25.
Catcgory Estimated acres ctu al acres % accuracy
oare soil 1,299 1,.22 91%
forest 816 858 95%
grass, forage, grain 1,911 2,002 95%
Therefore, these tests on three categories as interpreted from the SL-2
color film indicate approximate accuracies of 75% before ratio correction and
over 90% after ratio correction.
S-190B imagery was not collected over the tesL :ite on .lune 12, 1973, and
there has not yet been an opportunity to examine S-i)0B imagery from later passes.
Given the facts that resolution is better for the S-190B than the S-190A and that
later season phenology is more favorable for recognizing agricultural crop types,
the prognosis for crop acreage assessment from S-190B imagery appears to be good.


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