Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
37
Thematic mapping and data analysis for resource management
using the Stereo ZTS VM
Kurt H.Kreckel & George J.Jaynes
Bausch & Lomb Inc., Rochester, N. Y, USA
ABSTRACT: The new Vertical Measurement Module (VM) for the StereoZoom Transfer Scop^** permits spot and object
heights and terrain elevation measurements on relatively and absolutely oriented stereo photographs. Photo
X, Y, Z coordinates as well as orientation parameters may be stored and transferred to a printer, plotter, or
any external computer.
The Resource Measuring System (RMS 2 * * * * 7 '**) is ideally suited to accept the transferred data for the purpose of
conversion into map coordinates, listing, editing, printout and the generation of thematic overlay plots on
the RMS plotter at selected offsets and scales. The inherent RMS capabilities of feature analysis such as
area, perimeters, X/Y location, computation, classification and statistical analyses may be applied as desired.
1 INTRODUCTION
Thousands of resource managers worldwide in diverse
fields from forestry, biology, geology, stream bed
analysis, soil science, erosion management to the
matic mapping and map revision use the Bausch & Lomb
Stereo Zoom Transfer Scope (Stereo ZTS) in their
daily work. The intended use of the Stereo ZTS was
the capability of adding planimetric features to
existing base maps. The result is a special purpose
(thematic) map, or a revised map.
Such applications involve the superimposition of
a three dimensional virtual image created by stereo
scopic viewing of aerial stereo photographs onto a
map using objective lens zoom and map lens magnifi
cations as well as anamorphic stretch to obtain a
visual best fit between image and map. The operator
then simply draws any new features contained on the
photographs onto the map or overlay.
The basic Stereo ZTS has served its intended pur
pose, but it permits only the transfer of planimetric
features in relief to a map. The third dimension
was present, it could be viewed, but it could not be
numerically acquired and processed.
Numerous users and researchers (Weir, 1981), (Wal
ker, 1984) have suggested a need to utilize the
third dimension and to "acquire contours and other
forms of height information" in particular in the
category of instruments which are characterized by
"relatively low capital cost and simple operation
and maintenance". Such instruments can be operated
b.y the researcher interested in obtaining results
for his particular application. They do not need
specialists trained - for example - in photogrammetry
to operate them. A further argument has been pre
sented that such instruments are needed in "small
resource survey organizations in developed countries
who might require some in-house plotting facilities
hut feel unahle to justify the operation of a more
complex photogrammetric unit".
2 Addition of the Vertical Measurement Module
The development of the Vertical Measurement (VM)
module for the Stereo ZTS (Fig. 1) is an answer to
the need to make height and elevation measurements
and to utilize them for a data base and subsequent
processing in terms of editing, display, computation,
hard copy and planimetric and topographic plots.
The VM module being part of a new Stereo ZTS VM in
strument is furthermore retrofitable to existing
Stereo ZTS instruments.
Figure 1. Pictorial View of the VM equipped Stereo
ZTS.
3 Setup and Calibration (relative and absolute orien-
ration)
In its simplest form after initial setup and calibra
tion the VM module uses encoder information and both
keyboard entered, and computed parameters to measure
spot heights and terrain elevations.
Setup comprises the placement of the stereo pair
of photos on the stage, proper mounting of photo
graphs in photocarriers with fiducial alignment marks
and principal points marks, and placement and rota
tion of the mounted photographs for optimal stereo
viewing alignment.
Calibration allows performing relative orientation
for near vertical photography by solving differential
equations for six standard points using computerized
procedures which are based on well known principles
(von Gruber, 1924), (Hallert, B. 1960), and absolute
orientation using as few as three and as many as
five control points for scaling and leveling. The
computations of orientation parameters are accom
plished on-line by the built-in microprocessor.
Corrections are passed on to the relevant drives
such that the operator is not subjected to the
annoyance of y-parallax and the corresponding errors
in x parallax measurement. The VM module has been
successfully tested using special test photography
with omega and phi tilts of up to three degrees and
kappa rotations of as much as ten degrees.
