Calibration requires positioning and orienting each camera in 3D space and optionally setting the field of view. It involves recording a calibration video while moving a glowing marker through the capture volume in a descending spiral motion, ensuring it is always visible in all cameras. The video is then processed to detect marker positions. Ground points are marked to calculate the ground plane and set the scene scale based on measured camera height. The calibrated scene parameters are saved to an XML file.

1. CALIBRATION

2. Calibration is required to calculate
scene configuration
for each camera:
1. Position in 3D space
2. Orientation
3. (optional) Field of view
(if you don’t know FOV
for your camera)
3
Z
Y
1
2
X

3. Calibration in iPi DMC is based on
glowing marker tracking in 3D space
You can use a flashlight with Mini Maglite in candle
its reflector removed, or mode is recommended
other small glowing object

4. Step 1: run iPiRecorder and
• turn on Calibration mode checkbox
(for Sony PS Eye cameras)
• or set Exposure to reasonably small value
(for DirectShow-compatible web cameras)

5. Image from cameras should look dim
in calibration mode

6. Step 2: record calibration video
a. Start video recording
b. First couple of seconds of calibration video
should contain background only (no marker)
c. Then move slowly the marker through your
entire capture volume (front-top-right-
bottom-left-back-top-right-bottom-left)

7. Start from top and move the marker in a descending
No marker!
spiral motion
00:02 00:04 00:06 00:08
00:10 00:12 00:14 00:16
00:18 00:20 00:22 00:24

8. Move the marker in a descending spiral
motion
00:26 00:28 00:30 00:32
00:34 00:36 00:38 00:40
00:42 00:44 00:46 00:48

9. Marker should always be visible in all cameras
and never obscured by human body
00:50 00:52 00:54 00:56
00:58 01:00 01:02 01:04
01:06 01:08 01:10 01:12

10. d. Put the marker to the ground at each
corner and at the center of capture volume
Capture
Volume 

12. Step 3: stop recording
and check recorded video
At least first two seconds of video does not
contain marker
There is no motion blur (image of marker
looks like a round spot rather than an ellipse
or a luminescent line)
Marker is always visible in all cameras and
never obscured by human body

13. Step 4: process calibration video in
iPiStudio
• Please refer to the video tutorial:
Calibration_Tutorial.mp4

14. Resulting scene should look like this:
Green points designate correctly detected 3D marker positions.
Red points designate misdetected marker positions.
10-20% of red points should be considered normal.
Calibration should work correctly if you have at least 70% of green points.

15. Step 5: mark ground points
(at least three)
Go to frame where marker is on the ground and press Mark as ground button

16. The system uses ground points to calculate ground plane.
You need to define at least 3 ground points.

17. #1
measure vertical distance between
optical axis of camera and ground
Step 6: set scene scale
based on the measured camera height

18. Note: Height of camera can be used only if
ground is marked. If ground plane is not
defined, use distance between camera #1
and #2 to set scene scale
#1
#2

19. Step 7:
save result into *.scene.xml file
Click here to save
scene parameters to
XML file