Analytical photogrammetry demonstrated that automatic three dimensional mapping of forest terrain was technically feasible. The examples were black and white photography at scales of 1:10,000 and 1:24,000. The major improvement in terrain modelling was the addition of the capability of joining small quadrangles together to form one large model about equal to the effective area of the pair of photographs. Improvements of somewhat lesser importance include: (1) the use of up to 16 grey levels; (2) the elimination of several coordinate transformations; and (3) the annotation of three-tone hysocline maps with elevations

Amidon, E. L.

Russell, R. M.

Sharpnack, D. A.

English

NASA Technical Reports Server

REMOTE SENSING APPLICATIONS
IN FORESTRY
THE DEVELOPMENT OF AN EARTH RESOURCES
INFORMATION SYSTEM USING AERIAL PHOTOGRAPHS
AND DIGITAL COMPUTERS
by
^3 '
aidon
David A. Sharpnack
Robert M. Russell
O - j
Elliot L.' «
Pacific Southwest Forest and Range Experiment Station
Forest Service, U. S. Department of Agriculture
Annual Progress Report 30 September 1971
A report of research performed under the auspices of the
Forestry Remote Sensing Laboratory,
School of Forestry and Conservation
University of California
Berkeley, California
A Coordination Task Carried Out in Cooperation with
The Forest Service, U. S. Department of Agriculture
For
EARTH RESOURCES SURVEY PROGRAM
OFFICE OF SPACE SCIENCES AND APPLICATIONS
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
https://ntrs.nasa.gov/search.jsp?R=19720020678 2020-03-11T18:23:44+00:00Z
ACKNOWLEDGEMENTS
This research is being conducted under the Earth Resources Survey
Program in Agriculture/Forestry under the sponsorship and financial
assistance of the National Aeronautics and Space Administration, contract
No. R-09-038-002. The equipment used and saiary of the principal investi-
gator, as well as a portion of the salaries of several other professional
employees, were contributed by the Forest Service.
Grateful acknowledgement is given the University of California,
School of Forestry and Conservation, for their cooperation in providing
doctoral candidates to assist in this study.
TABLE OF CONTENTS
Acknowledgements j
Work performed during period covered by this report
Automated digital terrain modelling 1
Earth resources information system 2
Automated photo interpretation 3
Work currently in progress
Automated digital terrain modelling 5
Earth resources information system 6
Automated photo interpretation 6
Literature cited 6
i i
THE DEVELOPMENT OF AN EARTH RESOURCES
INFORMATION SYSTEM USING AERIAL
PHOTOGRAPHS AND DIGITAL COMPUTERS
by
El Hot L. Ami don
David A. Sharpnack
Robert M. Russel1
Pacific Southwest Forest and Range Experiment Station
Forest Service, U. S. Department of Agriculture
WORK PERFORMED DURING PERIOD COVERED BY THIS REPORT.
Automated Digital Terrain Modelling.
This work in analytical photogrammetry was provided by Dr. Jan Van
Roessel. He demonstrated that automatic three-dimensional mapping of forest
terrain was technically feasible. The examples were black and white photog-
raphy at scales of 1:10,000 and 1:24,000. However, extensive testing w i l l
be required to accurately predict costs for a wide range of conditions.
For example, obtaining a standard error of elevation of 1.5 meters would
cost about 33 cents per acre at a scale of 1:30,000. But we don't know
the cost per acre if the standard error were doubled.
The major improvement in terrain modelling was the addition of the
capability of joining small quadrangles together to form one large model
about equal to the effective area of the pair of photographs.
Improvements of somewhat lesser importance include; 1) the use of
up to 16 grey levels, 2) the elimination of several coordinate trans-
formations, and 3) the annotation of three-tone hysocline maps with
elevations.
The evolution of the digital mapping system can be traced in annual
progress reports beginning in 19&9 (1,2). A thorough description of the
system is contained in his doctoral thesis (3). The most recent published
description is contained in a paper delivered at the International Union
of Forestry Research Organizations in the spring of 1971 (**) . This last
item demonstrates the need for incorporating forest recognition capa-
b i l i t i e s into the system.
Earth Resources Information System.
This work in computer mapping was provided by Elliot Ami don, David
Sharpnack and Robert Russell. The following algorithms of the Earth
Resources Information System have been completed and are available for
distribution:
A. Subprograms
1. Data acquisition and editing
a. Read digitizer tapes
b. Convert digitizer data to computer form
c. Edit digitizer data and check for errors
d. Remove superfluous points from a boundary
2. Processing
a. Close a boundary
b. Thin a boundary
c. Compute the area within a boundary
d. Determine whether a given point is within a boundary
e. Intersection of 2 boundaries
f. Union of 2 boundaries
3. Output
a. Print points or boundaries
b. Plot points or boundaries on digital plotter
-2-
B. Main (uti l i ty) Routines
1. Print contents of a digit izer tape
2. Plot contents of a digit izer tape
A U. S. Forest Service mapping contractor used l : 55 f OOO IR color,
RB-57 photography of the Stanislaus National Forest to up-date 1 :15,8^0
panchromatic photography. This work is a part of a pilot project to apply
our research on multi-stage sampling and the Earth Resources Information
System to the current problem of developing a management plan for the
Stanislaus National Forest.
Programming of the Resource Information System continues. One program
wi l l transform digi t izer coordinates to the Lambert Conformal coordinate
system. Another program wi l l enable the use of Universal Transverse
Mercator coordinates. One system can be transformed to another via
geodetic coordinates.
A systematic work-flow procedure is being devised and tested using
110 maps of the Stanislaus National Forest. Map data are combined with
multi-stage sampling to estimate current timber volume and wi th growth
information to predict future volumes. About 20 maps have been manually
digit ized, processed on an Univac 1108, and plotted on a CalComp plotter.
Automated Photo Interpretation
This pattern recognition work was provided by David Sharpnack. The
development of an automated photo interpretation scheme for classifying
land classes on 1:110,000 Ektachrome transparencies is continuing. The
data was collected on a PDS micro-densitometer. Ninety to 180, 32 x 32
blocks of density readings on each of 11 land types was recorded.
-3-
Densit ies were recorded using red, green, and blue f i l ters as well as
with no filter. Land classes include water, rock, brush, grass and 7
sizes and densities of timber.
The screening of variables for inclusion in a classi f icat ion model
has been started. The f irst variables examined were the f irst four moments
of the distribution of densities in each 32 x 32 data block. The distrib-
ution of these variables were plotted for each land class for the four
fi l ter types. We found that the distributions of these moments were
essential ly the same over all land classes. Differences that were found
were due to the dist inct ly multi-model nature of the distributions. These
variables do not appear to be useful for a linear discriminant function
but might be used in an empirical distribution classif ication model. A
comparison of the plotted distr ibutions showed very l i t t le difference
between f i l ters.
To examine this lack of difference more closely sample points were
selected from each land class and moment correlation coefficients were
calculated for all fi lter pairs. For example, the r between the red fi lter
density and the green filter density was computed for 100 points. This
was done for 3 separate samples of 100 points in each of 11 land classes.
The r was calculated for all possible pairs of f i l ters; e.g. red-green,
red-blue, red-clear, green-blue, green-clear, and blue-clear. All 198 r's
were highly signif icantly different from zero. They ranged from about .3
to .99. Thus over most land classes the information provided by the second,
third, and fourth f i l ter is slight. Following a suggestion by Nancy Norick
of the Remote Sensing Project at PSW, the r's were recalculated after sub-
tracting the clear reading from the red, green, and blue readings. Of these
-4-
198 r's only 151 were highly significantly different from zero. The
absolute values of the coefficients ranged from .002 to .840. This
improvement in the independence of the filter readings was most notice-
able for water where the r's ranged from .002 to .318. A separate
study has been started to search for better filters and filter combi-
nations to further improve the usefulness of multi-filter density
read!ngs.
The second set of variables to be tested is the coefficients of the
power function of the Fourier Transform. The Fourier Transform was found
for each 32 x 32 data block using a Fast Fourier Transform program. To
facilitate the examination of the frequency distributions of the 1024
power coefficients for 1278 data blocks in 11 land types, the coefficients
were summed into 16 groups. Each group sum is a measure of the power in
l/l6th of the two dimensional frequency spectrum. The distribution of
these 16 variables was plotted for each land class for the red filter
minus no filter data. Because of the high cost of these calculations on
a digital computer only the red filter densities have been studied so far.
Of the 11 land types only water has a distinctly different distribu-
tion for some of the power coefficients. The importance of this difference
and that of some smaller differences w i l l be tested using linear discrimi-
nant functions.
WORK CURRENTLY IN PROGRESS
A. Automated Digital Testing
Automated digital terrain modelling operational testing of this
system ceased with the resignation of Dr. Jan Van Roessel in 1971.
-5-
B. Earth Resources Information System
The work-flow procedure for manually digitizing the 110 maps of the
Stanislaus National Forest is being refined continuously. An alternative
data input device is also being examined -- the PDS scanning micro-
dens itometer. The maps are reduced 8 times onto a panchromatic negative.
An appropriate combination of spacing and aperatures is sought so that
the lines are neither too wide or broken. Algorithms are being developed
to thin the lines, find nodes, and number the segments correcting nodes.
These segments then enter the established system and are processed like
hand-digitized segments.
C. Automated Photo Interpretation
Testing of the power coefficients of the Fourier Transform w i l l con-
tinue by estimating and testing coefficients for the linear discriminant
functions.
LITERATURE CITED
(1) Langley, P. G., et al. 19&9- The development of an earth resources
information system using aerial photographs and digital computers.
Annual Progress Report, Remote Sensing Applications in Forestry, NASA
Contract No. R-09-038-002. For; Earth Resources Survey Program, OSSA/
NASA. By: Pacific Southwest Forest and Remote Experiment Station,
Forest Service, USDA, 43p.
(2) Langley, P. G., et al. 1970. The development of an earth resources
information system using aerial photographs and digital computers.
Annual Progress Report, Remote Sensing Applications in Forestry, NASA
Contract No. R-09-038-002. For; Earth Resources Survey Program, OSSA/
NASA. By; Pacific Southwest Forest and Remote Experiment Station,
Forest Service, USDA, ^ 3p.
-6-
(3) Van Roessel, Jan W., 1970. A wildland resource mapping system using
digitized aerial photographs. Unpub. doctoral thesis. Univ. of Calif.,
Berkeley, California.
(4) Van Roessei, Jan W., 1971. Automated mapping of forest resources
from digitized aerial photographs. Proc. 15th IUFRO Congress,
Gainesville, Florida, 1971: PP- 177-188
-7-


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