Scanlab RTC 5 PC Interface Board Installation And Operation Manual page 162

The coefficients m ... m
11 22
mation matrix M are set via
T
set_matrix_list:
m
M
=
T
m
With the general transformation matrix M
above matrices (M and M
S R
as further transformations for scaling, rotating,
mirroring or skewing objects can be defined:
• Scaling by the factors k
k
–
M
=
T
0

• Rotation by the angle

cos
–
M
=
T

sin
–
For instance, the command
set_matrix( 1, 0.5, -0.866, 0.866, 0.5, 1 )
defines – for the primary scan head connector –
an immediate rotation by 60° (counterclockwise)
around the center of the image field. This can also
be achieved via the command set_angle(1,60).
• Mirroring around the Y axis (flipping in the X
direction):
M
=
T
• Mirroring around the X axis (flipping in the Y
direction):
M
=
T
• Mirroring around the first dimension diagonal
(exchanging the X and Y coordinates):
M
=
T
• Skewing in the X direction by the angle
(slanting):
1
–
M
=
T
0
–
Example: set_matrix( 1, 1, -0.25, 0, 1, 0 )
®
RTC 5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
of the general transfor-
set_matrix or
m
11 12
m
21 22
, the two
T
, as special case) as well
and k :
X Y
0
X
k
–
Yi
:

sin
–
o o

cos
o
1 0
–
0 1
1 0
0 1
–
0 1
1 0


sin
–
o
1
–
o
A general transformation defined via
set_matrix_list can also represent a combination of
various transformations (the user can calculate the
corresponding matrix M by multiplying the corre-
T
sponding individual matrices in the correct order).
Notes
• The described coordinate transformations are
primarily intended for small corrections when
setting up the scan system relative to the image
field. Separate settings for scaling and rotations
thereby provide more handling flexibility in
comparison to a single matrix setting.
• Initialization (via load_program_file) results in
an offset of (0|0|0) and in matrices M
M , each predefined as identity matrices.
T
• Each matrix or offset definition overwrites prior
definitions.
®
• The RTC 5 calculates the total matrix M indepen-
dently of the order in which the offset and
individual transformation matrices were defined.
• The value range of scaling factor k for the scaling
matrix M is [–16 ... +16]. The value range for the
S
coefficients of the general transformation matrix
M is [–50 ... +50]. Also be sure that the value
T
range [–50 ... +50] for individual coefficients of
the total matrix M are not exceeded; otherwise
calculation of the corrected coordinates might
result, under some circumstances, in overflows.
• Rotations are exclusively around the centerpoint
of the image field; mirroring is relative to the
axes. It is the user's responsibility to calculate and
make available suitable offset translations.
• For each definition, the parameter at_once can
be used to specify whether the new setting
should have immediate effect on the current
position (at_once = 1 or 3) or whether it should
only be provisionally collected and intermediately
stored (at_once = 0 or 2). For collection via list
commands, the commands don't necessarily
need to directly follow each other. The most
recently issued at_once parameter value deter-
mines when a (collected) transformation takes
effect.
• Before the (possibly collected) total transfor-
mation is applied to the current position, the
"laser active" laser control signals with at_once
= 0 to 2 will be switched off; but with
at_once = 3 the laser control signals remain
unaffected.
set_matrix or
, M and
S R
162