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.