How to Record Video with Action Cameras

Prerequisites

1. At least three action cameras.
   • cameras may be of different models but must support one and the same pair of resolution and FPS
2. All these cameras must be marked by some unique name/label to distinguish from each other.

   For example:

   

3. Optics of each camera must be calibrated.

   

   Important! You have to calibrate camera optics for resolution and FOV (view angle) settings you're going to use during motion capture session.

Scene Set-up

It is almost the same as with web cameras:

• mount the cameras on tripods
• point the cameras that actor is fully visible in all cameras

Tip: It is convenient to use smartphone application connected to camera via Wi-Fi for image preview because some models don't have display and others may be mounted too high to see their displays.

Tip: We recommend to mark boundaries of area where actor is fully visible. You can use electric or masking tape for this needs.

• measure height of each camera over floor/ground

You can see example of scene set-up from the sample:

Four Important Things

When recording using action cameras there are four very important recommendations you have to follow:

1. Use one and the same resolution and FPS on all cameras.
2. After recording of scene calibration sequence cameras must be in totally stable position. In other case results of calibration become invalid.
3. Video in each camera must contain a few seconds of clear scene (no actor, no moving objects, no glowing markers, etc.). It is required to evaluate background.
4. Some short and sharp (visible exactly in one frame of video) event(s) must be recorded in each video. It is required to synchronize videos from different cameras during creation of multi-camera video.

Uniform Resolution and FPS

Don't forget to set one and the same resolution and FPS for all cameras you're using during motion capture session.

Tip: 720p (1280 x 720) resolution is recommended for full body motion capture needs in most cases (except very large capture area).

Note: 60 or 90 FPS is optimal for capturing of most of the motions. As to 120 FPS: it requires good lighting conditions and tracking will last 2x times longer in comparison with 60 FPS.

Don't Touch Cameras

You shouldn't touch cameras after recording of scene calibration sequence till the end of all action recordings. There are two major options how to achieve this:

• use some remote control or smartphone application over Wi-Fi connection to start/stop recording
• or don't stop recording at all until the end of all action sequences.

The first option is preferable because it allows to save disk space and time required to copy and convert videos.

 

Background

Don't forget to record clear scene in each camera. This is required to evaluate background.

Tip: You can record clear scene only once for each lighting conditions and reuse it for different videos.

Synchronization Event

When you're recording scene calibration video, it can be the moment when you turn on/off flash light (or Sony Move) which you use as a glowing marker. But be aware that flash light must be visible in all cameras at this moment.

When you're recording action video, you can also blink by flash light (or Sony Move). But we recommend to use external on-camera powerful flash in manual mode like:

Use Test firing feature of your on-camera flash.

You can see an example of using such synchronization in the sample video:

Tip: Starting from version 4.2.0, iPi Recorder has Sync by Flash button in toolbar of Video Builder, which allows to synchronize videos in fully automatic manner based on flashes. If you're going to use this feature, it is recommended to have multiple flashes in each video. For example: before and after action/calibration sequence, or simply several times in succession.

Note: If you're using GoPro Smart Remote Control then please be informed that it is not guaranteed ideal synchronous start/stop of video recording by different cameras. For this reason, it is worth to use some sharp visual event like firing of on-camera flash even in combination with GoPro Smart Remote Control.

Scene Calibration and Action Sequences

In other aspects recording with action cameras is absolutely the same as with web cameras (Sony PS3 Eye and Logitech C922). Therefore, you can follow appropriate user guides for web cameras:

• Multiple PS Eye Cameras Calibration
• Recording Actor's Performance