V-Stars Operation Manual

Using the INCA3 Digital Camera

and V-Stars version 4.4 SR2h software

**[The Basics]{.underline}**

Michael O'Boyle

Fermi National Accelerator Laboratory

Batavia, IL 60510, U.S.A.

**[Step 1:]{.underline}**

**Targeting:**

**1) Target Options:**

A)  Stick-on targets for surfaces. (3mm and 6mm)

B)  1" targets for fiducials. (0, 45, and 90 degree)

C)  Vector targets for tooling balls. (45 and 90 degree)

> **[Note:]{.underline}** when using extensions on tooling balls, always
> use
>
> the same amount of extension on each ball.

D)  Coded targets for camera resection. (flat and rotatable)

**2) Order of Targeting:**

A)  Points of interest. (control, fiducials, etc.)

B)  Rotatable Codes.

C)  Flat Codes.

D)  Scale Bars.

**Scale Bars: (Invar)**

Normally 2 scale bars are used. One horizontal to the object and one
vertical. The bars should be at least the same size as the object
whenever possible and should be placed on the object being referenced.
It may not be possible to place a bar on an object in an as-found survey
since more than one object is being surveyed, (ex. magnet and control).

**Autobar:**

The autobar (crucifix) gives the survey a starting coordinate system. It
should be placed in a location so that it will appear in an optimum
number of photos.

**It is imperative that none of the targeting be moved once the
photography starts**. Obviously, rotatable targets and codes can be
rotated, hence the name rotatable. If flat codes become dislodged or
disturbed, remove them from the job immediately. In the case of large
jobs, only one set of codes may be used, since each set has duplicate
code numbers.

Coded target layout or spacing is dependent on object size and ones
distance from the object. In other words the closer one is to the object
the more concentrated the code dispersement must be to achieve proper
overlapping of photos.

**[Step 2:]{.underline}**

**Camera Set-up:**

1)  Remove the lens cap and place on the holder at the base of the
    camera.

2)  Attach the viewfinder to the top of the camera.

3)  Install the PCMCIA card in the slot at the top left of the camera.
    Push down until fully seated and close the door. The back of the
    card should face the back of the camera. **[Note]{.underline}**: the
    card can be removed when the camera is on, as long as the green busy
    light at the back, right, top of the camera is not on or flashing.

4)  Switch the camera on using On/Off switch at the lower left face of
    the camera. The LCD screen on the top of the camera will light up
    and you will hear 3 beeps. **[Note]{.underline}**: camera may take
    up to 45 seconds to come on.

5)  Set the job number using the two black buttons at the top right back
    of the camera. Depress and release both buttons. The LCD screen at
    the top of the camera will show Set Job Number with a number.
    Toggling one of these two toggle buttons can change this number.
    When starting a job you must toggle to a Job \# with 0 frames.

6)  Set the exposure by pressing the two black buttons again until Set
    Exposure is displayed. Toggle the setting to Auto Exposure.

7)  Set the strobe by pressing the two black buttons again until Set
    Strobe Power is displayed. Under most circumstances, toggle the
    strobe power to 9. This is based on target size and distance from
    the object.

> **[Note]{.underline}**: One can also toggle to Auto if unsure.

8)  Set the measurement mode by pressing the two black buttons again
    until Set Measurement Mode is displayed. For our purposes, the
    measurement mode is always toggled to On.

**[Note]{.underline}:** If at any point during the camera on or photo
taking process, one hears a continuous beeping, this means one of two
things; either the battery is dying or you are running out of memory on
the PCMCIA card. In the first case, you should immediately shut down the
camera and replace the battery. The battery is located on the front left
of the camera and is similar to a common video camera battery. Extra
batteries are kept on the charger in John Greenwood's office. Please put
the dead battery on charge. If one has advanced warning of an upcoming
V-Star job, it is a good idea to check the battery charger situation the
day before. After installing the dead battery on the charger an
approximate time to recharge will be displayed in approximately one
minute. In the second case, one should remove the memory card and delete
any jobs that have already been processed. The camera will return to the
same job and frame as when the card was removed.

**[Step 3:]{.underline}**

**Taking Pictures:**

Because the exposure and strobe were set to Auto, a test picture must be
taken in a representative location of the job to set the exposure and
strobe. Point the camera in the direction of the object or area to be
surveyed and simultaneously push the upper toggle and black trigger
buttons at the upper right corner of the camera face. The camera will
flash and the exposure and strobe will be set automatically. You are now
ready to take pictures.

Things to remember when taking pictures:

1)  Triangulation Requirements:

    A.  Need two different sightings of every point (four is the true
        > minimum).

    B.  Need good intersection angles between camera positions for each
        > target (60-120 degrees is good).

2)  Resection Requirements:

    A.  Need to see Autobar or four known points codes) in every picture
        > (points cannot be in a line).

    B.  Need at least 12 well-distributed points in every photo (but
        > twenty is better).

3)  Self-Calibration Requirements:

    A.  Need to roll camera by 90 degrees (at least once, more is
        > better).

    B.  Need at least twenty well-distributed points in the entire
        > measurement (forty is better).

4)  Overlap Requirements:

    A.  Need at least three common points (but more is better).

    B.  Common points cannot be in a line (triangle or better).

5)  Scale Requirements:

    A.  At least one known distance, usually two, preferably three.

    B.  Scale length is as long as practical (preferably the size of the
        > object being measured).

6)  Measurement Accuracy:

> Measurement accuracy is affected by four interrelated factors.

1)  Camera Resolution.

2)  Object Size.

3)  Number of Photographs.

4)  Geometric Layout.

> **[Note]{.underline}**: In most cases, the only thing one has control
> over is the number of photographs taken and to a lesser extent, the
> geometric layout. Like everything else, there is normally restricted
> space in which to do your job. Therefore, one can control geometry to
> some extent, but **the best way to increase accuracy is simply by
> taking more pictures.**

7)  Rotatable Targets and Codes:

> Remember when taking photos on an overlapping job, that one must make
> sure to always keep the rotatable targets and codes pointed in the
> direction of the camera.

8)  Minimum Angles:

> As a general rule of thumb, it is best to maintain a minimum angle of
> 45 degrees to the surface of the object being photographed. This angle
> is a good compromise between the quality of intersection angles and
> the quality of the target image.

9)  Where to Start:

> It is good practice whenever possible to begin taking photos
>
> at the area of your points of interest.
>
> **[Note]{.underline}:** When taking pictures the camera will either
> single beep or double beep after the photo is taken. The single beep
> indicates that enough known targets have been identified to
> successfully solve the individual photo. The double beep indicates
> that less than 4 known points (codes or autobar) have been identified.
> It is possible to solve these photos later by adding known points
> after the job has been bundled. However, it is easier, quicker and
> more efficient to just delete these photos and retake a similar photo,
> making sure to have at least 4 known points in the frame. The process
> for deleting frames is to hold down the red delete button on the top,
> left, front of the camera until Delete frame with the number of the
> last frame you shot appears in the LCD window. Hit the red delete
> button again and the frame is deleted with the display now showing
> Delete frame and the preceding frame number. After a few seconds the
> Ready/Done screen will reappear and one can continue taking photos.
>
> Also, there is a Laser Pointer feature on the camera for pointing the
> camera when not looking through the viewfinder. The pointer is
> activated by pressing the down toggle button on the top, right, back,
> of the camera. You will recall that this is the lower of the two
> toggle buttons.
>
> **[Step 4:]{.underline}**
>
> **Downloading and Processing Pictures:**

1)  Remove the PCMCIA card from the camera (make sure the busy light is
    > not blinking).

2)  Turn on the laptop and make sure V-Star software version 4.4 is
    > installed on the desktop.

3)  Install the card into the laptop, face-up in the appropriate slot
    > (top or bottom, either will work).

4)  Open V-Stars 4.4 on the desktop.

5)  Go to File; New.

6)  Name new file and Open.

7)  Select Camera window opens. Choose Browse.

8)  Double click any other V-Star job.

9)  Double click camera file (I3_0029.CAM).

10) V-Stars project opens with job name at top.

11) Right click on Pictures in left tree.

12) Click on Set Image Path.

13) Double click on Job# set in Step2:5 above. The photos will be
    > imported into the job.

14) Expand the window to show all the frames.

15) Go to Project on top task bar and choose Automeasure.

16) Measure Project window opens. Turn off attended mode (remove check
    > mark).

17) Click Begin. **[Note]{.underline}**: Pictures will scan
    > individually. A Green frame around each picture initially
    > indicates presence of the autobar. A Red frame initially indicates
    > the picture is unsolved because of an unknown coordinate system.
    > Next, a bundle adjustment runs to solve the picture stations.
    > Next, automatching runs to tie the pictures together. Next, the
    > final bundle runs. In the unattended mode this all happens very
    > quickly and one may not even be able to tell what is going on. The
    > Final Bundle results are displayed.

18) Assuming the bundle solves. Click Accept.

19) Close Measure Project Window.

> The following is a procedure developed through experience to quickly
> process a job and get the necessary results for the desired points**.
> This is [not]{.underline} the only way to process a V-Star job.**

20) Click in Frame 1 photograph. This expands the photo to full screen
    > and allows one to identify the targets.

21) Start naming targets. This is done by clicking on the pencil with
    > the small globe next to it, (global rename cursor), in the task
    > bar. As you type the desired target name, a window will
    > automatically appear showing the target name you are typing. After
    > typing the name hit return. The target name that you have typed
    > will now appear as the heading at the top of the zoom window. You
    > will note as the cursor nears the desired point, the target will
    > appear in the zoom window. Make sure the target is framed in the
    > green box in the zoom window and click the mouse. The target has
    > now been named in every photo it appears in.

> > **[Note]{.underline}:** if the zoom window is active, the
> > target-naming window will not automatically appear. Click the cursor
> > in the picture frame to activate.

22) Continue this procedure using necessary photos until all desired
    > targets have been renamed.

23) It is now time to enter the scale bar values.

24) Right click on Scalebars at the bottom of the menu tree.

25) Click on New

26) Double click on Label 1 and rename to the same target name as you
    > chose in Step 21 above. Usually the name used is SB followed by
    > the rough length of the scale bar followed by dash 1. (ex. a
    > 48.0001" scale bar would be named SB48-1 and SB48-2 on its two end
    > points. Tab over to Label 2 and rename. Tab to 0.0000 in the
    > distance column and enter the exact length of the scale bar (invar
    > +two scale holders+ two targets, ex. 48.0001 from above). Repeat
    > this step for the other scale bars.

27) Rerun the bundle by choosing Projects, Bundle, Run, from the task
    > bar.

28) When Bundle window is displayed hit Start.

29) When the bundle is complete, click More in the Points section of the
    > bundle display. At this point you will see the results for each
    > target measured.

30) Points identified with a red dash are considered bad. There are many
    > different reasons they can be bad. This includes the residual
    > values being too high; not matching in enough pictures; not enough
    > rays into the target; etc. **If a target you need appears as bad,
    > in most cases you will need to take more pictures in the area of
    > this point**. If a target you don't need appears as bad, you can
    > disable it by right clicking on the name and choosing Disable.

31) Points identified with a yellow diamond are considered weak. Points
    > may be considered weak for the same reason that they're bad only
    > not to the same extent. Unneeded weak points may also be disabled.
    > Needed weak points can be strengthened in different ways. One way
    > is to disable bad frames in the right window of the Points Summary
    > window. It is important to note that the results of a weak point
    > may still be well within the accuracy tolerance of the job. **In
    > other words weak can be good**.

32) Points identified with a green plus are considered good. These
    > points will only improve with the disabling of the bad and the
    > weak points.

33) When you have completed point editing, close the Points Summary
    > window.

34) Click Start in Bundle window. Bundle will rerun.

35) After rerunning the bundle the point results will change. In some
    > very rare cases the bundle results will get worse. This usually
    > happens when a critical point has been disabled. For example, you
    > may have disabled a weak code, which was critical to the tie from
    > frame to frame. In other words, be very careful when disabling
    > codes. This is learned only through experience.

36) If the bundle results are acceptable and all the required points are
    > known to the desired tolerance, click Accept.

> > **[Note:]{.underline}** acceptable results would be a residual RMS
> > in the low .3 range; a plan quality factor between 1 and 2 (the
> > closer to 1 the better); and no bad points among the points of
> > interest. But, the bottom line is sigma x, y, and z values within
> > the desired tolerance of the measurement, normally .002".

37) At this point the job is ready to hand over to the Task Manager for
    > final processing.