Operation and Features
3-10
Basler L301kc
DRAFT
To better understand the concept of spatial correction, let’s consider a simple example. In our
example, we will make the following assumptions:
• The optics and the distance between the camera and the conveyor have been arranged so
that we have a 1 to 10 magnification. This means that an area of 0.14 mm x 0.14 mm on the
object will create a 14 µm x 14 µm image on one pixel.
• Each step of the encoder represents a 0.14 mm movement of the conveyor. (This means that
the image on the sensor will move 14 µm for each step of the encoder).
• We trigger a line capture on each step of the encoder.
Now, consider a single 0.14 mm wide area on the object and call this area A. Assume that the
image of area A is falling directly on the red line of the sensor and that we have just performed a
line capture. In order to move the image of area A from the line of view of the red sensor line to
the line of view of the green sensor line, we will need 8 steps of the encoder. That is:
8 steps x 0.14 mm/step x 1/10 magnification = 112 µm movement of the image on the sensor
(112 µm is the exact center-to-center spacing between lines in the sensor)
To move the image of area A from the green sensor line to the blue sensor line, we will need 8
more steps of the encoder. Remember that we are performing a line capture on each encoder
step.
To get full RGB data for area A, we must take the blue line data and combine it with the green data
from 8 line captures earlier and the red data from 16 line captures earlier. In order to do this, the
data from the last 17 line captures must be stored in the camera and the camera must be able to
combine the information from the appropriate line captures.
Figure 3-11 sums up the line captures that must be combined to get full RGB data for area A. It
also shows what must be done to get full color information for area B, that is, a 0.14 mm area on
the object immediately after area A.
A parameter called the
Spatial Correction Delay in Lines
is used to tell the camera which line
captures should be combined (see Section
). In the case of our example, this parameter
should be set to 8. This setting would tell the camera to combine the blue line capture with the
green data from 8 line captures earlier and the red data from 16 line captures earlier
Figure 3-11: Sequence of Exposures and Line Readouts for Point A and Point B
Keep in mind that if the object is passing the camera in one direction, its image will cross over the
red line first, the green line second, and the blue line third. If the object is passing the camera in
the opposite direction, its image will cross over the blue line first, the green line second and the
red line third. In order to properly combine the line captures, the camera must know which way the
image is crossing the sensor. A parameter called the
Spatial Correction Starting Line
is used to
tell the camera how the image is crossing the sensor (see Section
for more information)
Summary of Contents for L301kc
Page 1: ...Basler L301kc USER S MANUAL Document Number DA00051806 Release Date 13 July 2007...
Page 4: ......
Page 14: ...Introduction 1 6 Baslert L301kc DRAFT...
Page 20: ...Camera Interface 2 6 Basler L301kc DRAFT Figure 2 3 Camera Frame Grabber Interface...
Page 102: ...Configuring the Camera 4 32 Basler L301kc DRAFT...
Page 116: ...Troubleshooting 6 10 Basler L301kc DRAFT...
Page 118: ...Revision History ii Basler L301kc DRAFT...
Page 120: ...Feedback iv Basler L301kc DRAFT...
Page 124: ...Index viii Basler L301kc DRAFT...