Copyright: Copyright © Integrated Quality, Inc.


0.  Contents
Contents

1.  Start IQ-FormFit Program

2.  Perform 2D Bestfit

Step 1  Read CAD Model

Step 2  Prepare CAD Model

Step 3  Read Measurement Data

Step 4  Prepare Measurement Data

Step 5  Perform 2D Bestfit

Step 6  View Deviations

Step 7  Export Results

3.  Perform 3D Bestfit

Step 1  Read CAD Model

Step 2  Prepare CAD Model

Step 3  Read Measurement Data

Step 4  Prepare Measurement Data

Step 5  Perform 3D Bestfit

Step 6  View Deviations

Step 7  Export Results


1.  Start IQ-FormFit Program
Start IQ-FormFit Program

To start IQ-FormFit program on your computer:

1.	From the Start menu on the taskbar of Windows 95/NT, select Programs | IQ-FormFit | IQ-FormFit.

Now IQ-FormFit is up and running.


2.  Perform 2D Bestfit
Perform 2D Bestfit

2D bestfit is the process of comparing your measurement data with a curve model. The operation consists of the following basic steps.

Step 1	Read CAD Model

Step 2	Prepare CAD Model

Step 3	Read Measurement Data

Step 4	Prepare Measurement Data

Step 5	Perform 2D Bestfit

Step 6	View Deviations

Step 7	Export Results


2D Bestfit:  Step 1  Read CAD Model
Step 1 Read CAD Model

Following these steps to read an IGES CAD model into IQ-FormFit:

1.	From the main menu, select menu File | Open, the Open file dialog box displays;

2.	Double click the mouse on the “Examples” folder;

3.	Select “IGES Files (*.IGS)” from the “Files of type” drop down list;

4.	Select the “FIT2D.IGS” file;

5.	Click the [Open] button to open the IGES file.

Now you see a cross section model displayed in the graphics window.


2D Bestfit:  Step 2  Prepare CAD Model
Step 2 Prepare CAD Model

A. Correct Curve Normal

Because IGES files do not correctly carry information identifying material "inside" the part and space "outside" the part, we may need to correct the material side of the part through the following steps. Assuming that you know what is material and what is void, the following sequence will allow you to check the "sense" of each model segment and to correct the sense where necessary.

1.	Select menu Curve | Test Curve Normal…, normal vectors will be displayed for all curve segements and the mouse cursor changes to the hand cursor for picking;

2.	Use the mouse to pick any of the four circles and the Test Curve dialog box displays;

3.	Click the [Flip] button to change circle normal to point to inside of circle since we know that this circle represents a hole;

4.	Repeat steps 2 & 3 for other circles;

5.	Press the <ESC> key on the keyboard to end curve normal testing and reset the mouse cursor.

Now the normal for each hole in this model is correct.

B. Assign Form Tolerance

Follow these steps to assign form tolerances to each curve and to display a tolerance band around the nominal.

1.	Select menu Curve | Set Form Tolerance…, the Set Curve Form Tolerance dialog box displays;

2.	Click the [Select All] button to select all the segments in the model;

3.	Type “0.05” in the “Upper” box to specify an upper tolerance boundary offset from the nominal by 0.05 (larger);

4.	Type “-0.05” in the “Lower” box to specify a lower tolerance boundary offset from the nominal by 0.05 (smaller);

5.	Click the [Set] button to set the form tolerances for the selected curves.

Now a tolerance band is displayed around each curve. To magnify the tolerance band, click on the [Magnify Deviation] button [image] on the tool box three time and you will see the current magnification factor shown on the status bar while the tolerance boundaries are further apart.

The tool box is on the left side of the screen. It contains buttons for the most frequently used menu commands. The [Magnify Deviation] button is the third button in the left column down from the top of the tool box.

C. Save Model File

Now the CAD model is ready for comparison with measurement data; but we want to save the model for later use.

1.	Select menu File | Save,  the Save As dialog box displays;

2.	Type “Fit2D” in the “File name” box;

3.	Click the [Save] button to save the file.

Now the prepared model is saved into file “Fit2D.FFD”;


2D Bestfit:  Step 3  Read Measurement Data
Step 3 Read Measurement Data

Follow these steps to read measured point data into IQ-FormFit:

1.	Select menu File | Open, the Open file dialog box displays;

2.	If the “Examples” folder is the current folder, you can skip this step. Otherwise, double click the “Examples” folder;

3.	Select “ASCII Data Files (*.DAT)” from the “Files of type” drop-down list;

4.	Select the “FIT2D.DAT” file;

5.	Click the [Open] button to open the data file;

6.	Select unit “Millimeter” as the unit of the data file;

7.	Click the [OK] button.

Now you see the measured point data displayed as dots in the graphics window.


2D Bestfit:  Step 4  Prepare Measurement Data (2D)
Step 4 Prepare Measurement Data

In most cases, measurement data are not strictly on the working plane, IQ-FormFit requires that the measurement data be projected to a selected working plane in order to perform a 2D bestfit. If the measurement device only outputs x and y coordinates, then IQ-FormFit will automatically set the z coordinate of each point to zero. In this case, the procedure described here is not necessary.

1.	Select menu Point | Project To Working Plane…, the Project Cloud to Working Plane dialog box displays; Default working plane is XY_PLANE;

2.	Click the [Select All] button to select all the point clouds;

3.	Click the [OK] button on the Project Cloud to Working Plane dialog box.

Now the measurement points have been projected onto the xy-plane of the world coordinate system.


2D Bestfit:  Step 5  Preform 2D Bestfit
Step 5 Preform 2D Bestfit

After the above steps, both the CAD model and the measurement data are ready for bestfitting. Follow these steps to bestfit the measurement data against the CAD model:

1.	Select menu  Bestfit | 2D Bestfit…, the Bestfit 2D Point Clouds to 2D Curves dialog box displays;

2.	Click the [All Clouds] button to select all the point clouds;

3.	Click the [All Curves] button to select all the curves;

4.	Click the [OK] button to start bestfitting.

Now the program starts the bestfit calculation and the Bestfit Progress dialog box displays. Once the calculation is done, the Bestfit Progress dialog box will disappear and the bestfitting results will be displayed in the Bestfit Results dialog box.

1.	Click the [Record Xform…] button, the Name for Transformation dialog box displays;

2.	Type “Xform_2D” in the “Name” box;

3.	Click the [OK] button on the Name for Transformation dialog box to accept the name and save the transformation so that the transformation can later be exported to a text file;

4.	Click the [OK] button to close the Bestfit Results dialog box.


2D Bestfit:  Step 6  View Deviations
Step 6 View Deviations

A. View Deviations Graphically

After bestfitting, the deviation of each point from the curve model is displayed as a "whisker" in the graphics window. You can also change the magnification factor for the deviations to better see the variation.

1.	Click the [Magnify Deviation] button [image] on the tool box to magnify the deviations;

2.	Click the [Demagnify Deviation] button [image] on the tool box to demagnify the deviations;

3.	Select menu Deviation | Magnification | Magnification Factor…, the Set Magnification Factor dialog box displays;

4.	Type “20” in the “New Factor” box;

5.	Click the [OK] button to accept the new magnification factor.

B. View Deviation List

You can view the deviation values through the following steps.

1.	Select menu Deviation | View Dev Information to switch to deviation list view;

2.	Double click “circle_1_fit1” in the “Dev Cloud List”;

3.	Select menu View | Start Point to turn off display of start point of deviation;

4.	Select menu View | I J K to turn off display of I-J-K or deviation;

5.	Select menu View | Graphics to switch back to graphics view;

6.	Repeat first step to switch to deviation list view;

7.	Click the [X] button at the right end of the main menu bar to close the deviation list view. (Note: The [X] button on the program title bar at the top right corner of the screen is for exiting the program.)


2D Bestfit:  Step 7 Export Results
Step 7 Export Results

A. Export Transformation Matrix

The following procedure exports the transformation matrix obtained from bestfitting to a text file for use in other applications.

1.	If the current view is the deviation list view, select menu View | Graphics to switch to graphics view;

2.	Select menu File | Export | Xform…,  the Export Transformation dialog box displays;

3.	Select the transformation you wish to export from the Transformation List if there are more than one transformations available for exporting;

4.	Click the [OK] button to close this dialog box,  the Export Transformation To File dialog box displays;

5.	Type “Fit2D” in the “File name” box;

6.	Click the [Save] button;

Now the transformation matrix is saved to a text file “Fit2D.TXT”.

B. Export Deviations

Deviations obtained from bestfit can be exported to a text file through the following steps.

1.	Select menu File | Export | Dev Cloud…, the Export Deviation Clouds dialog box displays;

2.	Select “circle_1_fit1” from the deviation cloud list;

3.	In the output options section of the dialog box, select the fields that you wish to export;

4.	Click the [OK] button to close this dialog box,  the Export ASCII Deviation File dialog box displays;

5.	Type “circle1” in the “File name” box;

6.	Click the [Save] button.

Now the deviation cloud for CIRCLE_1 is saved to a text file “CIRCLE1.DEV”.


3.  Perform 3D Bestfit
Perform 3D Bestfit

3D bestfit is the process of comparing your measurement data with a surface model. The operation consists of the following basic steps.

Step 1	Read CAD Model

Step 2	Prepare CAD Model

Step 3	Read Measurement Data

Step 4	Prepare Measurement Data

Step 5	Perform 3D Bestfit

Step 6	View Deviations

Step 7	Export Results


3D Bestfit:  Step 1  Read CAD Model
Step 1 Read CAD Model

Follow these steps to read an IGES CAD model into IQ-FormFit:

1.	From the main menu, select menu File | Open, the Open file dialog box displays;

2.	Double click the mouse on the “Examples” folder;

3.	Select “IGES Files (*.IGS)” from the “Files of type” drop-down list;

4.	Select the “FIT3D.IGS” file;

5.	Click the [Open] button to open the IGES file;

Now you see the surface model displayed in the graphics window.

Follow these steps to change the view of the model.

1.	Hold down the <Shift> key on the key board and drag the mouse over the graphics window to dynamically change the view;

2.	Drag the three scroll bars around the graphics window to change the view around one of the screen axes;

3.	Select menu  View | Standard View | Isometric to change to the standard isometric view;


3D Bestfit:  Step 2  Prepare CAD Model
Step 2 Prepare CAD Model

A. Correct Surface Normal

Because IGES files do not correctly carry information identifying material "inside" the part and space "outside" the part, we may need to correct the material side of the part through the following steps.

1.	Select menu Surface | Display Surface Shading, surface shading will be displayed and the two sides of a surface are displayed in different colors(Gray Color: Outside, Magenta Color: Inside);

2.	Select menu Surface | Test Surface Normal…, the mouse cursor changes to the hand cursor for picking;

3.	Use the mouse to pick the surface whose real outside is displayed in magenta color, then the Test Surface dialog box displays and the surface normal arrows are also displayed;

4.	Click the [Flip] button to change surface normal to point to the outside of the model;

5.	Press the <ESC> key on the keyboard to end surface normal testing and reset the mouse cursor.

Now the normal for each surface in this model is correct.

B. Assign Form Tolerance

Follow these steps to assign form tolerances for each surface.

1.	Select menu Surface | Set Form Tolerance…, the Set Surface Form Tolerance dialog box displays;

2.	Click the [Select All] button to select all the surfaces in the model;

3.	Type “0.2” in the “Upper” box to specify an upper tolerance boundary offset from the nominal by 0.2 (larger);

4.	Type “-0.2” in the “Lower” box to specify a lower tolerance boundary offset from the nominal by 0.2 (smaller);

5.	Click the [Set] button to set the form tolerance(s) for the selected surfaces.

Tolerance band will not be displayed for surfaces, but it will be used during bestfit calculation to determine weather a deviation is out of tolerance band or within tolerance band. Out-of-tolerance deviations will be displayed in colors different from within-tolerance deviations.

C. Save the Model File

Now the CAD model is ready for comparison with measurement data; but first we want to save the model for later use.

1.	Select menu File | Save, the Save As dialog box displays;

2.	Type “Fit3D” in the “File name” box;

3.	Click the [Save] button.

Now the prepared model is saved into file “Fit3D.FFD”;


3D Bestfit:  Step 3  Read Measurement Data
Step 3 Read Measurement Data

Follow these steps to read measured point data into IQ-FormFit:

1.	Select menu File | Open, the Open file dialog box displays;

2.	If the “Examples” folder is the current folder, you can skip this step. Otherwise, double click the “Examples” folder;

3.	Select “ASCII Data Files (*.DAT)” from the “Files of type” drop-down list;

4.	Select the “FIT3D.DAT” file;

5.	Click the [Open] button to open the data file;

6.	Select unit “Inch” as the unit of the data file;

7.	Click the [OK] button.

Now you see the measured data displayed as dots in the graphics window.


3D Bestfit:  Step 4  Prepare Measurement Data
Step 4 Prepare Measurement Data

If your measurement data is taken by a CMM, usually you need to set the probe radius for the measurement data for probe radius compensation in bestfit. The data sets we just read in are actually scan data. Therefore, we do not need to set probe radius(leave them to zero as default). However, to get you familiar with the program, let’s practice how to set probe radius.

1.	Select menu Point | Set Probe Radius…, the Set Probe Radius dialog box displays;

2.	Select “scan1” in the point cloud list,

3.	Type “0.0” in the “Probe Radius” box; ( this is just for practice purpose, in your case, type your probe radius here )

4.	Click the [Set] button to set probe radius for “scan1” and “scan1” is excluded from the point cloud list;

5.	Repeat steps 2-4 to set probe radius for other point clouds. You can select multiple point clouds if they have the same probe radius.


3D Bestfit:  Step 5  Perform 3D Bestfit
Step 5 Perform 3D Bestfit

After the above steps, both the CAD model and the measurement data are ready for bestfitting. Follow these steps to bestfit the measurement data against the CAD model:

1.	Select menu  Bestfit | 3D Bestfit…, the Bestfit Point Clouds to Surfaces dialog box displays;

2.	Click the [All Clouds] button to select all the point clouds;

3.	Click the [All Surfaces] button to select all the surfaces;

4.	Click the [OK] button to start bestfitting, Bestfit Progress dialog box displays;.

5.	After about 8 to 10 iterations, the convergence ratio becomes very small. We can click the [Stop Iteration] button to terminate the bestfit calculation.

When the bestfit calculation is done, the bestfitting results will be displayed in the Bestfit Results dialog box.

1.	Click the [Record Xform…] button, the Name for Transformation dialog box displays;

2.	Type “Xform_3D” in the “Name” box;

3.	Click the [OK] button on the Name for Transformation dialog box to accept the name and save the transformation so that the transformation can later be exported to a text file;

4.	Click the [OK] button to close the Bestfit Results dialog box.


3D Bestfit:  Step 6  View Deviations
Step 6 View Deviations

A. View Deviations Graphically

After bestfitting, the deviation of each point from the surface model is displayed as a "whisker" in the graphics window. You can also change the magnification factor for the deviations to better see the variation.

1.	Click the [Magnify Deviation] button [image] on the tool box to magnify the deviations;

2.	Click the [Demagnify Deviation] button [image] on the tool box to demagnify the deviations;

3.	Select menu Deviation | Magnification | Magnification Factor…, the Set Magnification Factor dialog box displays;

4.	Type “10” in the “New Factor” box;

5.	Click the [OK] button to accept the new magnification factor.

B. View Deviation List

You can view the deviation values through the following steps.

1.	Select menu Deviation | View Dev Information to switch to deviation list view;

2.	Double click “surface_1_scan2_fit1” in the “Dev Cloud List”;

3.	Select menu View | Start Point to turn off display of start point of deviation;

4.	Select menu View | I J K to turn off display of I-J-K or deviation;

5.	Select menu View | Graphics to switch back to graphics view;

6.	Repeat first step to switch to deviation list view;

7.	Click the [X] button at the right end of the main menu bar to close the deviation list view. (Note: The [X] button on the program title bar at the top right corner of the screen is for exiting the program.)


3D Bestfit:  Step 7  Export Results
Step 7 Export Results

A. Export Transformation Matrix

The following procedure exports the transformation matrix obtained from bestfitting to a text file for use in other applications.

1.	If the current view is the deviation list view, select menu View | Graphics to switch to graphics view;

2.	Select menu File | Export | Xform…,  the Export Transformation dialog box displays;

3.	Select the transformation you wish to export from the Transformation List if there are more than one transformations available for exporting;

4.	Click the [OK] button to close this dialog box,  the Export Transformation To File dialog box displays;

5.	Type “Fit3D” in the “File name” box;

6.	Click the [Save] button;

Now the transformation matrix is saved to a text file “Fit3D.TXT”.

B. Export Deviations

Deviations obtained from bestfit can be exported to a text file through the following steps.

1.	Select menu File | Export | Dev Cloud…, the Export Deviation Clouds dialog box displays;

2.	Select “surface_1_scan2_fit1” from the deviation cloud list;

3.	In the output options section of the dialog box, select the fields that you wish to export;

4.	Click the [OK] button to close this dialog box,  the Export ASCII Deviation File dialog box displays;

5.	Type “Surface1Scan2” in the “File name” box;

6.	Click the [Save] button.

Now the deviations from scan2 to surface_1 are saved to a text file “Surface1Scan2.DEV”.