Blade 3.1 / 3.3. 1 Summary

Blade 3.1 / 3.3.1 Calibrating Cameras

Deborah R. Fowler

click here for Blade 3.1 / 3.3.1 User's Guide

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see corresponding video (earlier version but similar)

Posted on Dec 5  2013
Updated March 25  2016

Blade 3.1 / 3.3.1 Calibrating Cameras

Connect the cameras

At the top left side - make sure you click Connect - you will see the cameras respond by lighting up bright red leds, with a blue and a green light. The blue light indicates that cameras are connected. Once we finish the wand wave the green lights will stop blinking and be on solid.

The gearbox icon above the plug icon will turn red when connected.

Calibrate the cameras

There are 4 steps we will follow to calibrate the cameras. Note that if your overall error is > .4, you should try another calibration. Anything under .3 is excellent.

Note about mouse controls: When moving in the Vicon Blade window, RMB forward and backward is an in and out motion with the mouse. Hold both right and left mouse keys down to move around.

Click the Camera Layout button (under Studio Activities) to reconfigure the workspace.

Make sure the menu below Connect is set to CIRCLE FIT (this will only be set to CIRCLE FIT for calibration and RECONSTRUCT or SOLVE for capture).

The process of calibrating the cameras involves the following:
  • Adjust the camera's settings (stripe display ) to get accurate data (full bubble gum  affects all cameras)
    • Make sure strobe is set to 1 (maximum) and threshold to .3 with gain set to 2 and circular left unchanged at .5.
    • Strobe is the red bar, threshold the yellow, gain white, circularity green (for descriptions see the online documentation)
    • If you want to adjust a specific camera, use the single bubble gum to affect one camera only - double check the location by selecting the camera (double click) and look for the blinking blue button on the camera itself)
  • Auto Masking (in 3.3.1) - with the wand hidden and no other reflective materials out, click Start Auto Masking - you will see it quickly cycle thru the cameras - hit stop. (Cleans up everything, camera views should all look clear at this point.) Note in Blade 3.1 and lower this was called Auto Threshold
  • Wand Wave - expand the options (triangle in 3.1, ... in 3.3.1) and ensure the Combined Wand (last entry in the dropdown menu) is set - should be by default - and begin your wand wave - try to build the cameras up evenly paying attention to the weaker cameras. You may now use Auto Stop (checkbox) - a limit of 3000 (Refinement frames) works well for our system.
  • Setting origin - place the wand level in the center of the volume and click start then stop. Wand is facing the front (desk) of the volume with the tail pointing back toward the green screen room.
  • Calibrate Floor Plane - place a dozen (3.1) or minimum 5 (3.3.1)  markers randomly on the floor particularly along the edge and a few in the center and then click start and stop. Experiments have shown that this helps with feet capture.
  • SAVE CALIBRATION (just in case you want to reload it later on ie. blade crashes - locations and settings are saved now). If the overall error is < .3 this is excellent. If not, repeat the steps. NOTE: Blade 3.1 saves location and settings, 1.7 only saved location). Please note that for Blade 3.3.1 the errors may be higher (.3 is good, only > .4 is not good). Never hurts to double check your settings after a crash.

In rare cases you may find the need to adjust the camera settings individually, however since our equipment is monitored closely there is no need - the steps are described in Advanced Camera Adjustments and are included for completeness.

Why calibrate the cameras each capture day?
Running the calibration ensures that Blade software knows the precise location of the cameras to construct 3D points in space from the 3D camera data. This calibration will ensure a clean capture. You may save settings for another session, however keep in mind that changes from movement of any kind (trains, people walking on the floor above, etc.) can affect the cameras. It is good practice to calibrate each capture session.

The goal is to build your cameras data up as evenly and quickly as possible.

What is a good wand wave?
Walk around the perimeter of the capture volume waving the wand up and down and in circular motions. The cameras should reach a value of > 3000 to 5000 in the status report window. The green lights on the cameras will light solid green to indicate sufficient data (as well as the font color of the number in the lower right window). The values of projError are low - this is good. Expect an error with the new wand below .2.

Where way should the wand be placed to set the origin?
Place the wand with the handle pointed to the back of the room. This will define the orientation of the space. Be sure Combined Wand (last entry in the selection menu on the Start Wand Wave options). It should be placed in the center of the volume, parallel to the front of the volume and set level so the bubbles are level. After Set Origin the ring of cameras should be parallel to the floor.

Now the cameras are calibrated, it's time to capture a Range Of Motion (ROM) for your actor.