Experiment devices.

<p>Experiment devices.</p

The spatial distribution of initialized control points.

<p>The range of curve is the same with that of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133905#pone.0133905.g006" target="_blank">Fig 6</a>, and it is an eighth of the moving space which is symmetrical around </p><p></p><p></p><p></p><p><mrow></mrow><mi>m</mi></p><p><mi>m</mi><mi>s</mi></p><p></p><p>P<mn>0</mn></p><p></p><p></p><p></p>. The initialized control points ‘○’ take control of the surrounding space which is partitioned by adjacent control points.<p></p

Coordinate systems of object moving.

<p>O_ms-X_msY_msZ_ms represents the measurement reference.</p

An Improvement of Pose Measurement Method Using Global Control Points Calibration

<div><p>During the last decade pose measurement technologies have gained an increasing interest in the computer vision. The vision-based pose measurement method has been widely applied in complex environments. However, the pose measurement error is a problem in the measurement applications. It grows rapidly with increasing measurement range. In order to meet the demand of high accuracy in large measurement range, a measurement error reduction solution to the vision-based pose measurement method, called Global Control Point Calibration (GCPC), is proposed. GCPC is an optimized process of existing visual pose measurement methods. The core of GCPC is to divide the measurement error into two types: the control point error and the control space error. Then by creating the global control points as well as performing error calibration of object pose, the two errors are processed. The control point error can be eliminated and the control space error is minimized. GCPC is experimented on the moving target in the camera’s field of view. The results show that the RMS error is 0.175° in yaw angle, 0.189° in pitch angle, and 0.159° in roll angle, which demonstrate that GCPC works effectively and stably.</p></div

The frequency of occurrence of M_III.

<p>Only the filtered control points are displayed. The red line is the cutoff frequency.</p

The RMS error of the results.

<p>The x axis is used to distinguish the yaw angle, pitch angle, and roll angle.</p

System Diagram.

<p>System Diagram.</p

The frequency of occurrence of M_I.

<p>Only the filtered control points are displayed. The red line is the cutoff frequency.</p

Coordinate of feature points.

<p>The coordinate is the center of the hole.</p><p>Coordinate of feature points.</p

The measurement reference of GCPC.

<p>The (<i>a</i>_<i>x</i>, <i>b</i>_<i>x</i>, <i>d</i>_<i>x</i>) and (<i>e</i>_<i>x</i>, <i>g</i>_<i>x</i>) corresponds to the </p><p></p><p></p><p></p><p>P<mi>m</mi><mi>c</mi></p><p><mrow></mrow><mi>x</mi></p><p></p><p></p><p></p> while the (<i>a</i>_<i>y</i>, <i>b</i>_<i>y</i>, <i>d</i>_<i>y</i>) and (<i>e</i>_<i>y</i>, <i>g</i>_<i>y</i>) corresponds to the <p></p><p></p><p></p><p>P<mi>m</mi><mi>c</mi></p><p><mrow></mrow><mi>y</mi></p><p></p><p></p><p></p>. The two dotted circles are determined by the two solid arcs respectively.<p></p