project undertaken by Baltimore County. A total of 869 
aerial photographs were taken by a Leica RC-30 camera 
at a scale of 1:6000 utilizing airborne kinematics GPS 
procedures. Sixty-five diapositives (5 strips of 13 
photos) of this project were selected for this study. 
Characteristics of these two projects are given in Table 1. 
  
  
  
  
  
  
  
  
Project Description Texas Maryland 
Camera Wild RC-20 Leica RC-30 
Photo Scale 1:3000 1:6000 
Forward/Side Overlap 80 / 60 % 60 / 30 % 
Number of Strips 3 5 
Number of Photos 21 65 
Terrain Relief 75-80 m 10-110m 
  
  
  
  
Table 1. Texas and Maryland Project Description 
Intergraph PhotoScan was used for scanning aerial 
photographs, and the InterMap Digital (IMD) workstation 
with its mensuration software (ISDM) was used for 
interactive and semi-automatic point transfer and 
triangulation. Finally, MATCH-AT, developed by Inpho of 
Germany, was used for a complete automatic aerial 
triangulation. 
2.1 PhotoScan 
PhotoScan is a high-resolution, radiometrically and 
geometrically precise flatbed scanning system that was 
designed specifically to address the requirements for 
high-end photogrammetry and image processing film 
conversion. PhotoScan converts photographic 
information from black-and-white or color and from 
positive or negative film sheets into continuous-tone 
digital image data at a rate of up to 2 million pixels per 
second (Figure 1). 
The PhotoScan fixed optics produce a 7.5 um pixel size 
camera system which is digitized to a minimum of 10 
bits prior to compensation and digital aggregation to the 
user-specified resolution. Resolution options include the 
basic 7.5 um pixel size as well as 15 um, 22.5 um, 30 
um, 60 um and 120 um sizes (Madani, 1991). 
2.2 InterMap 6887 ImageStation 
The InterMap 6887 ImageStation digital stereoplotter 
(IMD) is an analytical stereoplotter designed for users 
needing photogrammetric functionality for map 
compilation and revision, engineering mapping and 
revision, orthophoto production, transportation alignment 
cross-section collection, digital terrain collection, GIS 
input and revision, and close-range applications (Figure 
2). 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996 
  
Figure 1. The PhotoScan System 
IMD provides stereo graphics on a 24-bit true color 27- 
inch monitor. A JPEG compression/decompression 
processor allows the use of high-resolution scanned 
imagery while minimizing the file/storage size of the 
image. An infrared emitter and liquid crystal glasses 
provide a high-resolution 3-D image. IMD is also offered 
with the VI-50 image computer and 64 megabytes of 
onboard ECC memory as a standard configuration. An 
ergonomically designed work/digitizer table (34 x 22 inch 
sensitized area), which includes a 10-button two-handed 
controller, and a cantilevered monitor table complete the 
IMD configuration (Madani, 1993). 
  
D 
Figure 2. The InterMap 6887 ImageStation 
2.3 ImageStation Digital Mensuration 
ImageStation Digital Mensuration (ISDM) software 
provides a multi-image (up to 6 images at once) multi- 
sensor point transfer and measurement environment for 
a photo triangulation workflow. 
    
  
   
     
   
     
   
   
   
   
  
  
   
   
  
   
   
   
   
   
  
   
  
   
      
   
    
    
   
  
   
  
   
   
   
    
   
  
  
  
  
  
  
   
   
  
  
  
  
  
  
   
   
   
   
   
    
The hi 
allows 
flexible 
provide 
in mul 
this ty 
reliabil 
the 1 
manip 
perfor 
provid 
relative 
Some 
o PI 
ar 
2.4 M 
MATC 
progre 
perfor 
points 
This p 
part, 1 
block 
height 
seque 
exteri 
syste 
comb 
appro 
suffici 
MATC 
applie 
instar 
block 
each 
meth« 
all ir 
that ; 
Secor 
to ger 
Finall 
on the 
paran 
This r 
on the 
photc 
comp 
EINB 
(Heu