ical 
>ur- 
me 
ces 
on- 
fol- 
the 
ven 
els, 
dif- 
and 
an 
oft- 
igh 
ve- 
are 
r, it 
ree 
ree 
nt 
sor 
gle 
fast 
So 
] of 
by 
reo 
for 
fast adjustment. Since the LMT functionality 
enables the operator to control this adjust- 
ment by software means (using single 
stage movements e.g. during relative 
orientation or data capturing for aerial trian- 
gulation), this feature is removed. 
After upgrading, the setting of a systematic 
deviation in height measurements, at the 
original BC performed by the so called spe- 
cial keys, may be set at the LMT user 
interface. 
The speed control lever of the BC for pro- 
filing is removed because the LMT supports 
a very flexible profiling speed control with 
all encoder input devices. Particularly, the 
speed control by handwheels makes a finer 
adjustment of the stages speed possible. 
Like the original BC real-time processor 
system, LMT supports the measuring mark 
position display. 
The so called "PFKB5" function keyboard 
for simplified user input at the BC's applica- 
tion software user interface is supported 
further on for those users who intend to 
continue working with their familiar BC ap- 
plication software. 
The pair of two footpedals of the BC is ex- 
tended to three to achieve LMT compatibili- 
ty; the interpretation of the switches 
depends on the application software that is 
enabled by LMT to interpret 6 different sig- 
nals: pressed and released for all three 
switches. 
Like the original BC real-time processor 
System, LMT sends a message to the host 
application carrying status information 
about the BC Ortho/Pseudo lever. Pack- 
ages running on the host application com- 
puter can access this information very 
easily. However, current versions of appli- 
cation software have to be adapted if this 
feature is required. 
Like the original BC real-time processor 
System, LMT checks and consideres the 
status of the optical positive/negative 
95 
changeover switch, i.e. diapositives and 
negatives may be restituted in the same 
way as before. The different positioning of 
the stages is handled by LMT itself, without 
affecting the application software at all. 
The following table gives an overview com- 
parison about the features supported by the 
original and the upgraded BC instrument. 
  
  
  
  
  
  
  
  
  
  
  
  
feature original BC | upgraded BC 
free hand controller * * 
profiling speed control * + 
coordinate display + * 
joy stick for fast * * 
movements 
good photo illumination + * 
measuring mark posi- + + 
tion display 
status information + + 
ortho/pseudo 
status information + + 
positive/negative 
zero index of ground + + 
height 
b, movement + o 
potential for superim- - * 
position upgrade 
  
  
  
  
  
  
  
Fig.2 : overview comparison of original BC with 
upgraded BC instruments; 
+ = is supported; 
= is supported and improved; 
0 = is not supported but replaced 
by different tools; 
= is not supported 
3.3 Computer Replacement 
The real-time microprocessor system on 
the original BC is replaced by an Intel 
based PC that fits into the cabinet of the 
BC. If the application host computer is a PC 
as well, both computers fit into that cabinet. 
The communication between both plat- 
forms is serial.