CALIBRATION

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 FOVfor your camera)

X

Y

Z

1

2

3

Calibration in iPi DMC is based onglowing marker tracking in 3D space

You can use a flashlight with its reflector removed, or

other small glowing object

Mini Maglite in candle mode is recommended

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)

Image from cameras should look dim in calibration mode

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)

00:02 00:04 00:06 00:08

00:10 00:12 00:14 00:16

00:18 00:20 00:22 00:24

No marker!Start from top and 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

Move the marker in a descending spiral motion

00:50 00:52 00:54 00:56

00:58 01:00 01:02 01:04

01:06 01:08 01:10 01:12

Marker should always be visible in all camerasand never obscured by human body

d. Put the marker to the ground at each corner and at the center of capture volume

Capture Volume

Step 3: stop recordingand 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

Step 4: process calibration video in iPiStudio

• Please refer to the video tutorial: Calibration_Tutorial.mp4

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.

Step 5: mark ground points

(at least three)

Go to frame where marker is on the ground and press Mark as ground button

The system uses ground points to calculate ground plane.

You need to define at least 3 ground points.

Step 6: set scene scalebased on the measured camera height

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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

Step 7:save result into *.scene.xml file

Click here to save scene parameters to

XML file