How to Diagnose Inaccurate VTube-LASER Measurements - Revision history

Mcone at 20:46, 11 August 2022

2022-08-11T20:46:32Z

Mcone: /* Recalibrate the probe and the scanner (FARO Only) */

2019-02-01T02:23:37Z

‎Recalibrate the probe and the scanner (FARO Only)

Mcone: /* Recalibrate the probe and the scanner */

2019-02-01T02:23:25Z

‎Recalibrate the probe and the scanner

Mcone: /* Two Kinds of General Issues: Outliers or Inaccuracies */

2019-02-01T02:22:44Z

‎Two Kinds of General Issues: Outliers or Inaccuracies

Mcone: /* Has the external lighting changed? */

2019-02-01T02:17:26Z

‎Has the external lighting changed?

Mcone: /* Has the external lighting changed? */

2019-02-01T02:17:06Z

‎Has the external lighting changed?

Mcone: /* Aiming the lens at bright light */

2019-02-01T02:16:35Z

‎Aiming the lens at bright light

Mcone: /* Aiming the lens at bright light */

2019-02-01T02:15:54Z

‎Aiming the lens at bright light

Mcone: /* Aiming the lens at bright light */

2019-02-01T02:15:36Z

‎Aiming the lens at bright light

Mcone: /* Aiming the lens at bright light */

2019-02-01T02:10:49Z

‎Aiming the lens at bright light

@@ Line 25: / Line 25: @@
 If linear deviations (like tangent point deviations) swing by 0.039, then there may be a problem. The only situation where this is not true would be if the material is very deformed.<br><br>
-==Two Kinds of General Issues: Flyers or Inaccuracies==
+==Two Kinds of General Issues: Fliers or Inaccuracies==
-The problem could be either flyers or inaccuracies (or both combined).
+The problem could be either fliers or inaccuracies (or both combined).
 Perform this test:
 [[image:vtube-laser_wobbledeviation.png|300px|right]]
-STEP 1 - Scan a cylinder straight. Before calculating the cylinder centerline, release the green button and let the scanned points draw on the screen.  Orbit the scanned points.<br><br>'''Do you see any flyers in the VTube viewport when you let go of the green button after scanning?''' flyers are points that should not be in the scan. This is a very common issue - especially when using cut planes.<br><br>
+STEP 1 - Scan a cylinder straight. Before calculating the cylinder centerline, release the green button and let the scanned points draw on the screen.  Orbit the scanned points.<br><br>'''Do you see any fliers in the VTube viewport when you let go of the green button after scanning?''' fliers are points that should not be in the scan. This is a very common issue - especially when using cut planes.<br><br>
-STEP 2 - If there are no flyers, then put the scanner in range of some object and press the red button to calculate the centerline. Examine the '''wobble deviation''' by looking at the XY values in the Cylinder fit window.<br><br>'''Do either of the XY values swing widely?''' The wobble deviation is the higher of either the X or the Y deviation values in the cylinder fit window that pops up during cylinder measurements.
+STEP 2 - If there are no fliers, then put the scanner in range of some object and press the red button to calculate the centerline. Examine the '''wobble deviation''' by looking at the XY values in the Cylinder fit window.<br><br>'''Do either of the XY values swing widely?''' The wobble deviation is the higher of either the X or the Y deviation values in the cylinder fit window that pops up during cylinder measurements.
-===If you see flyer points in the viewport, then...===
+===If you see Flier points in the viewport, then...===
-Even a few flyers can severely impact the calculation of cylinder centerlines. It is important to setup the system to get rid of flyers (for example with the Cut Plane feature.) For example, extra care has to be taken with Newport tables.  The flyer issue is NOT a point accuracy issue.<br><br>
+Even a few Fliers can severely impact the calculation of cylinder centerlines. It is important to setup the system to get rid of Fliers (for example with the Cut Plane feature.) For example, extra care has to be taken with Newport tables.  The Flier issue is NOT a point accuracy issue.<br><br>
-There are two types of flyers:
+There are two types of Fliers:
-# Real flyers - These are points scanned from things near the tube.
+# Real Fliers - These are points scanned from things near the tube.
-# Phantom flyers - These are points created in space by overwhelming the camera with feedback that is too powerful. For an example of phantom flyer points, see [[Scanning on a NEWPORT type table]].
+# Phantom Fliers - These are points created in space by overwhelming the camera with feedback that is too powerful. For an example of phantom Flier points, see [[Scanning on a NEWPORT type table]].
 <br><br>
-===There are no flyers present - but there is still a problem, then...===
+===There are no Fliers present - but there is still a problem, then...===
-If you see significant changing wobble deviation values without flyer points, then you have eliminated the possibility of flyers, then you should look for other problems that could impact the accuracy of the system.<br><br>
+If you see significant changing wobble deviation values without Flier points, then you have eliminated the possibility of Fliers, then you should look for other problems that could impact the accuracy of the system.<br><br>
 ==Look for anything loose in the system that may cause the arm to shift when it is moved==

@@ Line 55: / Line 55: @@
 * Does the tube or table move at all during measurement? If you can see or feel any extra motion at all during measurement, then this will cause problems in repeatability. The entire setup must be absolutely still during measurement. If you can see or feel the environment moving around the arm, then this will always cause problems.<br><br>
-==Recalibrate the probe and the scanner (FARO Only)==
+==Recalibrate the probe and the scanner==
 Recalibrate the ball probe then the laser (in that order). If the arm cannot pass calibration of the ball probe or the laser scanner, then you will never get repeatable measurements.<br><br>See video 54 in the [[VTube-LASER Videos]] page for how to calibrate the probe and scanner.

@@ Line 55: / Line 55: @@
 * Does the tube or table move at all during measurement? If you can see or feel any extra motion at all during measurement, then this will cause problems in repeatability. The entire setup must be absolutely still during measurement. If you can see or feel the environment moving around the arm, then this will always cause problems.<br><br>
-==Recalibrate the probe and the scanner==
+==Recalibrate the probe and the scanner (FARO Only)==
 Recalibrate the ball probe then the laser (in that order). If the arm cannot pass calibration of the ball probe or the laser scanner, then you will never get repeatable measurements.<br><br>See video 54 in the [[VTube-LASER Videos]] page for how to calibrate the probe and scanner.

@@ Line 25: / Line 25: @@
 If linear deviations (like tangent point deviations) swing by 0.039, then there may be a problem. The only situation where this is not true would be if the material is very deformed.<br><br>
-==Two Kinds of General Issues: Outliers or Inaccuracies==
+==Two Kinds of General Issues: Flyers or Inaccuracies==
+The problem could be either flyers or inaccuracies (or both combined).
-−
-The problem could be either outliers or inaccuracies (or both combined).
 Perform this test:
 [[image:vtube-laser_wobbledeviation.png|300px|right]]
-STEP 1 - Scan a cylinder straight. Before calculating the cylinder centerline, release the green button and let the scanned points draw on the screen.  Orbit the scanned points.<br><br>'''Do you see any outliers in the VTube viewport when you let go of the green button after scanning?''' Outliers are points that should not be in the scan. This is a very common issue - especially when using cut planes.<br><br>
+STEP 1 - Scan a cylinder straight. Before calculating the cylinder centerline, release the green button and let the scanned points draw on the screen.  Orbit the scanned points.<br><br>'''Do you see any flyers in the VTube viewport when you let go of the green button after scanning?''' flyers are points that should not be in the scan. This is a very common issue - especially when using cut planes.<br><br>
-STEP 2 - If there are no outliers, then put the scanner in range of some object and press the red button to calculate the centerline. Examine the '''wobble deviation''' by looking at the XY values in the Cylinder fit window.<br><br>'''Do either of the XY values swing widely?''' The wobble deviation is the higher of either the X or the Y deviation values in the cylinder fit window that pops up during cylinder measurements.
+STEP 2 - If there are no flyers, then put the scanner in range of some object and press the red button to calculate the centerline. Examine the '''wobble deviation''' by looking at the XY values in the Cylinder fit window.<br><br>'''Do either of the XY values swing widely?''' The wobble deviation is the higher of either the X or the Y deviation values in the cylinder fit window that pops up during cylinder measurements.
-===If you see outlier points in the viewport, then...===
+===If you see flyer points in the viewport, then...===
-Even a few outliers can severely impact the calculation of cylinder centerlines. It is important to setup the system to get rid of outliers (for example with the Cut Plane feature.) For example, extra care has to be taken with Newport tables.  The outlier issue is NOT a point accuracy issue.<br><br>
+Even a few flyers can severely impact the calculation of cylinder centerlines. It is important to setup the system to get rid of flyers (for example with the Cut Plane feature.) For example, extra care has to be taken with Newport tables.  The flyer issue is NOT a point accuracy issue.<br><br>
-There are two types of outliers:
+There are two types of flyers:
-# Real outliers - These are points scanned from things near the tube.
+# Real flyers - These are points scanned from things near the tube.
-# Phantom outliers - These are points created in space by overwhelming the camera with feedback that is too powerful. For an example of phantom outlier points, see [[Scanning on a NEWPORT type table]].
+# Phantom flyers - These are points created in space by overwhelming the camera with feedback that is too powerful. For an example of phantom flyer points, see [[Scanning on a NEWPORT type table]].
 <br><br>
-===There are no outliers present - but there is still a problem, then...===
+===There are no flyers present - but there is still a problem, then...===
-If you see significant changing wobble deviation values without outlier points, then you have eliminated the possibility of outliers, then you should look for other problems that could impact the accuracy of the system.<br><br>
+If you see significant changing wobble deviation values without flyer points, then you have eliminated the possibility of flyers, then you should look for other problems that could impact the accuracy of the system.<br><br>
 ==Look for anything loose in the system that may cause the arm to shift when it is moved==

@@ Line 79: / Line 79: @@
 Is there any new lighting nearby? Is there a bay door open with sunlight flooding in - even through blinds?<br><br>
-[[image:vtl_with_sunlight_interference.png|800px]]
+[[image:vtl_with_sunlight_interference.png|700px]]
-[[image:vtl_without_sunlight_interference.png|800px]]
+[[image:vtl_without_sunlight_interference.png|700px]]
 ==Aiming the lens at bright light==

@@ Line 77: / Line 77: @@
 ==Has the external lighting changed?==
-Is there any new lighting nearby? Is there a bay door open with sunlight flooding in? (This is especially a problem for non-HD scanners.)<br><br>
+Is there any new lighting nearby? Is there a bay door open with sunlight flooding in - even through blinds?<br><br>
 ==Aiming the lens at bright light==

@@ Line 81: / Line 81: @@
 ==Aiming the lens at bright light==
 If the lens is aimed upward at bright lights or an open door, then this could be the cause of the problem. Try measuring with the scanner lens pointed away from external lights.<br><br>
 ==Is there a chance that you need the Cut Plane and forgot to measure it?==

@@ Line 82: / Line 82: @@
 If the lens is aimed upward at bright lights or an open door, then this could be the cause of the problem. Try measuring with the scanner lens pointed away from external lights.<br><br>
-[[image:vtl_with_sunlight_interference.png|400px]]
+[[image:vtl_with_sunlight_interference.png|600px]]
-[[image:vtl_without_sunlight_interference.png|400px]]
+[[image:vtl_without_sunlight_interference.png|600px]]
 ==Is there a chance that you need the Cut Plane and forgot to measure it?==

@@ Line 83: / Line 83: @@
 [[image:vtl_with_sunlight_interference.png|200px]]
-[[image:vtl_wihtout_sunlight_interference.png|200px]]
+[[image:vtl_without_sunlight_interference.png|200px]]
 ==Is there a chance that you need the Cut Plane and forgot to measure it?==