Quick Start Guide for Multiple Action Cameras Configuration

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Get Hardware

  • For recording get:
    • the action cameras or other stand-alone camcorders (a minimum of three)
      • all cameras must have big enough field-of-view and fixed optics (in other case auto-focus and zoom features must be turned off in advance)
      • also, all cameras must support one and the same pair of resolution and FPS
      • 720p (1280 x 720) resolution is recommended for full body motion capture needs in most cases (except very large capture area)
      • 60 or 90 FPS is optimal for capturing of most of the motions
      • see Cameras and Accessories#Action_Cameras for details
    • tripods or other attachments to fix cameras
    • a flashlight (Mini Maglite or Sony Move are recommended) for calibration needs
    • measuring tape or laser distance measuring tool to determine heights of cameras over floor/ground (for scale)
  • For processing get:
    • computer with DirectX 11 capable videocard (gaming-class GPU is highly recommended)
    • microSD-card reader to copy video from action cameras to computer (alternatively you can use USB cord, but microSD-card reader provides much higher speed as a rule)

Install

Prepare

  • Mark each camera by some unique nickname (number/letter/color/code)
    • you can use masking tape or sticky labels for these needs
    • examples of names:
  • Choose and set recording parameters on each camera (field-of-view, resolution, FPS)
    • remember that resolution and FPS must be set the same for all cameras
  • Calibrate camera optics for each camera using Calibrate Camera Optics tool in iPi Recorder. Save results to files with names which contain camera's nickname, resolution and field-of-view settings (for example: cameraA-720p-wide.iPiCam)

Record

Setup

  • Find a suitable space: as a rule not less than 13 by 13 feet (4 by 4 meters) but it depends on cameras field-of-view (wider field-of-view allows to record in smaller room).
  • Fix all cameras and point them to the center of capture area. Actor should be fully visible in all cameras in capture area.
    • examples of configurations can be found here
  • It is convenient to mark on the floor/ground boundaries of area where actor is fully visible. This is your capture area.
    • you can use electric tape or masking tape for these needs
  • Measure height of each camera over floor/ground. Write down these values somewhere like: 
camera A - 1.12 m
camera B - 1.65 m
camera C - 1.22 m
...

Record Calibration Sequence

To determine mutual position of cameras special calibration procedure is used:

  • Turn off the lights or at least turn the lights down low
  • Start recording on each camera
  • Let each camera to record at least few seconds of clear scene (no moving objects, no glowing marker) for background evaluation needs
  • Enter to the center of capture area and turn on your glowing marker (Mini Maglite or Sony Move)
    • Important.png
      Important! At this moment marker must be visible in all cameras for synchronization needs (see below).
  • Move the marker slowly through your entire capture volume (front-top-right-bottom-left-back-top-right-bottom-left). Start from top and move the marker in a descending spiral motion.
  • Touch the floor (ground) by marker at several (4 or more) different points.
  • For details see User Guide for Multiple PS Eye Cameras Configuration#Step 2: Record Calibration Video.
Important.png
Important! After recording of calibration sequence cameras must be in totally stable position. In other case results of calibration become invalid. For this reason you shouldn't touch cameras after recording of calibration sequence till the end of all action recordings.

For details see How to Record Video with Action Cameras.

Record Action Sequence

  • Actor should be dressed in a slim solid-color clothing:
    • recommended clothing: long-sleeve shirt, blue jeans or trousers, black shoes
    • deep, saturated colors are preferable
    • ideally, pants and shirt should be of different colors
    • clothes colors must have good contrast with background.
  • Record video of actor's performance:
    • please ensure that the whole body including arms and legs is mostly visible in all cameras during the performance
    • start from a T-pose
    • then goes actor’s performance
  • Before or after actor performance record clear scene (no actor, no moving objects) for at least few seconds. This part of video will be used to evaluate background during creation of multi-camera video (see below).
  • Also you need to record some very short "event" which is well visible in all cameras like flash of light from external on-camera flash. It is recommended to record such "event" at least two times: before and after actor's performance. This "event" will be used to synchronize videos from different cameras during building of multi-camera video(s) (see below).

Build Multi-Camera Synced Video(s)

In comparison to web cameras this is an extra manual step which is rather time consuming: you have to build multi-camera .iPiVideo file(s) from individual MP4/AVI/MOV/MPEG files recorded by each camcorder.

  • Create sub-folder on computer for each camera. It is convenient if name of sub-folder contains nickname of corresponding camera.
  • Use microSD-card reader or USB cable to copy all required video files from camera to corresponding sub-folder on computer.
  • Run iPi Recorder and click on Build Combined Video button in toolbar on home screen.
  • You're in Video Builder now.
  • Add video file from each camera by clicking Add Video button in toolbar and choosing appropriate file from camera's sub-folder.
    • Important.png
      Important! It's extremely important to add videos from cameras in one and the same order for each result multi-camera video. In other case cameras from scene calibration will not match cameras from action video.
  • It is convenient to set camera optics parameters right after adding video:
    • click PROPERTIES button on top of image from added camera
    • in the left panel click Load button in camera parameters section
    • choose appropriate .iPiCam file you saved for this camera during Preparation procedure
  • Also, for each camera you have to set sync frame using left PROPERTIES panel
    • manually:
      • click Edit button in sync frame section in this panel
      • using timeline choose frame with some short "event" like turning-on of marker during calibration video (the first frame where marker becomes visible) or flash of light
      • click Set to Current Frame button in toolbar
      • switch back to BUILD tab
    • automatically:
      • if you're using flashes as sync events then you can simply click Sync by Flash button in toolbar
  • On timeline choose interval with clear background (no actor, no moving objects, no glowing marker). Click Evaluate Background button in toolbar to evaluate background from this interval of video.
    • Alternatively, you can evaluate background for each camera individually using left PROPERTIES panel (see background section there) or even save/load background to/from file on disk.
  • Now choose interval on timeline which contains required calibration/action sequence and click Save Combined Video in toolbar.
  • Congratulations! Multi-camera synced .iPiVideo file is ready to be processed in iPi Mocap Studio.
  • Repeat these actions for each calibration/action sequence you recorded.

For detailed instructions see How to Build Synced Multi-Camera Video.

Process in iPi Mocap Studio

As soon as you create synchronized multi-cameras videos, you can process them in iPi Mocap Studio. And this processing is exactly the same as for the video recorded by iPi Recorder from web cameras like Sony PS Eye.

Process Calibration Video

  • Run iPi Mocap Studio.
  • Create new calibration project from calibration video.
  • Adjust selected range on timeline (Region of Interest, or ROI) so that it contains only frames where marker is visible.
  • Press Calibrate button.
  • Evaluate quality of calibration.
  • Adjust scene scale based on measured heights of cameras over the floor/ground.
  • Save results.

For more info see User Guide for Multiple PS Eye Cameras Configuration#Step 5: Process Calibration Video in iPi Mocap Studio.

Process Action Video

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