STEP-BY-STEP INSTRUCTION FOR EXAMPLE 3
The low-image-density recording samples are from a PIV test in a liquid bridge at a microgravity state. The seeded flow was recorded in a video system at a frame rate of 25 fps. The measurement was conducted in the cross section of the liquid bridge that has a diameter of 4mm, which is resolved by 450 pixels in the digital image. Detailed description of the experiments and data analysis can be found in papers  and . An evaluation procedure is suggested as follows.
Step 1: Open a video recording and importing the background image
- Execute file “Edpiv.exe” - The start window is shown on the screen;
- Select menu “File \ Open recording 1” to open “…\ PIVsamples \ 3_LidVideoRecordings \ 5500304.bmp”;
- Select menu “File \ Import B-mask” to import “…\ PIVsamples \ 3_LidVideoRecordings \ background.bmp”.
Step 2: Input imaging scale and time interval
- Click menu “Edit / Scale & time” in the start window to open dialogue box “Imaging scale / time interval”;
- Select radio button mm;
- Input 4 in edit box “Reading on ruler”;
- Input 450 in edit box “Corresponding pixels”;
- Input 20000 in edit box “Time interval [mu-s]”;
- Press “OK” button to return to start window.
Step 3: Subtract background & separate frames
- Press button “Show image” to display the video recording (Recording 1) in the picture frame;
- Press button “Processing” - The “Image processing” window appears;
- Click menu “Edit \ Image operation \ Subtraction” - Dialogue box “Image operation with/to …” appears;
- Choose “Boundary mask”, and then press “OK” button;
- Click menu “Edit \ Frame separation \ Video recording”;
- Answer “Yes” to question “Do you really want to separate this recording into two frames?” - Back to the start window.
Step 4: Set up evaluation parameters
- Click menu “Edit / Evaluation settings” in the start window to open the “Evaluation settings” window;
- Press “HPIT” button and then press button “C” on the right - Dialogue box “HPIT settings” appears;
- Press button “Method 2” and then press button “C” on the right - Dialogue box “Settings for particle position search…” appears;
- Set parameters as
- Press “OK” to close Dialogue box “Settings for particle position search…”
- Set other parameters in dialogue box “HPIT settings” as
- Close dialogue box “HPIT settings”
- Set parameters in the “Evaluation settings” window as
- Close “Evaluation settings” window.
Step 5: Evaluate the LID PIV recording pair
- Press button “Evaluation” in the start window - “Evaluation” window is opened;
- Click menu “Start” in “Evaluation” window;
- Answer “Yes” to question “Do you want to start an evaluation?”
- Press button “OK” to close the dialogue box that notices the end of the evaluation.
Step 6: Save evaluation results
- Click menu “File \ Save data” - Dialogue box “Save evaluation results” appears;
- Find a desired folder, type in a file name in the dialogue box;
- Press button “Save” to complete the saving procedure.
Step 7: Plot vector map
- Close EDPIV;
- Use TECPLOT to make plots.
Shu JZ; Legros JC; Gui LC; Xiong W (1997) The measurement of velocity distribution of liquid bridge at oscillatory state by PIV method, the Joint 10th European and 6th Russian Symposium on Physical Sciences in Microgravity, 15 -20 June, St. Pertersburg, Russia
Gui L; Merzkirch W; Shu JZ (1997) Evaluation of low image density PIV recordings with the MQD method and application to the flow in a liquid bridge. Journal of Flow Visualization and Image Processing, vol. 4: 333-343