Procedures for the Use of the PointGrey Flea3 FireWire Camera and ImageJ *

Transcription

1 Procedures for the Use of the PointGrey Flea3 FireWire Camera and ImageJ * * Although the following procedures are given for the Free Fall experiment, you can utilize the camera adjustments and settings, and the ImageJ tools in a similar manner for other experiments. For example, in the 2D Motion and Linear Momentum experiments the shutter speed is not critical since the pucks are moving slowly. The Rotation experiment uses the Angle tool in ImageJ rather than the Line tool. I. VIDEO CAPTURE A. Open Video Capture Application 1. Click on the FlyCap2 shortcut on the Desktop. A window appears, indicating the detected camera. (Figure 1) Figure 1. Opening the FlyCap2 application. 1

2 2. Click OK. Another window will open, displaying the image from the camera. 3. Zoom in at the object, focus, and then zoom out. The image should remain focused. Adjust the iris, if necessary. (Figure 2) Figure 2. Image from camera. B. Prepare for Video Capture Adjust Camera Settings 1. Click on the Show/Hide camera control dialog button. Another window appears with tabs on the left. The initial window shows Camera Settings. (Figures 3 and 4) Figure 3. Show/Hide camera control dialog button. 2

3 Figure 4. Main camera control window, Camera Settings. 2. Click on Standard Video Modes. Adjust the Frame Rate to 60 Hz. (Figures 5 and 6) Figure 5. Initial Standard Video Modes window. 3

4 Figure 6. Standard Video Modes window after choosing frame rate. 3. Next, click Advanced Camera Settings. Choose Timestamp and Shutter under Embedded Image Information. (Figure 7) Figure 7. Advanced Camera Settings window. 4

5 4. Go back to the Camera Settings window. Check to make sure the Frame Rate is 60 Hz, the same as when you changed it under the Standard Video Modes window. 5. Unclick the Auto box next to the Shutter setting. Adjust the shutter speed to ms. (Figure 8) This will ensure that the object s image will not be blurred in the video. Compare the two figures below. (Figures 9-10) Figure 8. Camera Settings window showing adjusted shutter speed. Figure 9. Blurred image of ball. Shutter speed is too slow. 5

6 Figure 10. Clear image of ball after adjusting shutter speed. C. Recording the Video 1. Click on the Capture video or image sequence button (red dot). The Recording Settings window will appear. (Figure 11) Figure 11. Capture video or image sequence red button. 2. On the bottom of the window, click on the Videos tab and then click on the Use Camera Frame Rate button. The frame rate of 60 Hz should appear in the box beside the button. Video recording should be uncompressed. (Figures 12-14) 6

7 Figure 12. Initial Recording Settings window. Figure 13. Click on the Videos tab in the Recording Settings window. 7

8 Figure 14. Click on the Use Camera Frame Rate button to set the proper fps setting. Video Recording Type is uncompressed. Note the Start Recording button on the lower right. 3. Before recording your video, it is necessary to first set the filename for your video file. At the top of the Recording Settings window, click on Browse. Determine where you want to save the file (ideally the Desktop), type in a filename, and then click Save. Make sure the file is listed at the location you chose. (Figure 14) 4. Position the photographic meter stick in the frame such that it is straight, level, or plumb, depending on what you are recording. 5. To begin recording your video, click on the Start Recording button on the lower right of the Recording Settings window. 6. To stop recording, simply click on the same button which had changed to Stop Recording. The file is in.avi format, and it is automatically saved with the filename you set in step 3 above. (Figure 14) 8

9 II. VIDEO ANALYSIS A. Open ImageJ Application 1. Once you are satisfied that you recorded and saved a good video, open the ImageJ application, which will be used for analyzing the video. 2. To open the video file, go to File Import AVI. Select your file. A window will then appear. Select Convert to Grayscale. (Figures 15 and 16) Figure 15. Open ImageJ application and import your video file. Figure 16. Convert video file to grayscale. 9

10 3. ImageJ conveniently obtains information about your video file. Go to Image Show Info. You will notice that the frame rate is listed. Take note of the accuracy of this reading. You may wish to use this information rather than simply using 60 fps or the timestamp on each frame as you take position measurements. (Figure 17) Figure 17. ImageJ provides information about your video file. 10

11 B. Calibrate Video and Set Measurements 1. Click on the Lines tool and choose the Straight line. (Figure 18) Figure 18. Lines tool button. 2. Draw a straight line along the length of the photographic meter stick. (Figure 19) Figure 19. Draw straight line along the length of the photographic meter stick. 11

12 3. Go to Analyze Set Scale. A Set Scale window appears. (Figure 20) a. The Distance in Pixels reading is the length of the straight line you drew along the meter stick. b. For Known Distance, type in , the meter stick s length. c. For Unit of Length, type in cm. Make sure you click on the box next to Global so that the scale is transferred to each frame of the video. Figure 20. Setting scale of the video. 12

13 4. Go to Analyze Set Measurements. Check box next to Invert Y Coordinates and uncheck any other boxes. You can set the number of decimal places as well. Click OK. (Figure 21) Figure 21. Setting measurements that will be displayed on the Measure window. 13

14 C. Taking Measurements 1. Click on the Point/Multi-point tool and choose Multi-point. (Figure 22) Figure 22. Point/Multi-point tool on ImageJ. 2. Position the crosshairs on the center of the ball and click. As you are clicking on the centers of the ball, notice the timestamp located at the upper left of the window. You have the option of using this timestamp or the frame rate for the t value in the data analysis graphs. (Figure 23) a. Advance the frame by using the > key on your keyboard, clicking on the centers of the ball as it falls. You will notice numbers appearing as you click. b. You can also zoom in the image to make it easier to see the center of the ball (Image Zoom In[+]). c. To go back a frame, use the < key on the keyboard. 14

15 Figure 23. Numbers appear while clicking on a sequence of images. 3. Go to Analyze Measure. A table of your measurements will appear in a separate window. On this window, go to Edit Copy. (Figure 24) Figure 24. Measurement table. 15

16 4. Open Excel and then paste your measurements in the Worksheet. (Figure 25) 5. Follow lab manual s instructions for data analysis, required charts, and error analysis. Figure 25. Copy and paste measurements to an Excel Worksheet. 16

17 III. DEFAULT CAMERA SETTINGS Figure 26. Initial Window When Opening Flycap2 Application. 17

18 Figure 27. Camera Settings window. 18

19 Figure 28. Standard Video Modes window. 19

20 Figure 29. Custom Video Modes window. 20

21 Figure 30. Camera Information window. 21

22 Figure 31. Camera Registers window. 22

23 Figure 32. Trigger/Strobe window. 23

24 Figure 33. Advanced Camera Settings window. 24

25 Figure 34. High Dynamic Range window. 25

26 Figure 35. Look Up Table Window. 26

27 Figure 36. Frame Buffer window. 27

28 Figure 37. Data Flash window. 28

29 Figure 38. System Information window. 29

30 Figure 39. Bus Topology window. 30

31 Figure 40. Recording Settings window for Images. 31

32 Figure 41. Recording Settings window for Videos. 32

33 Figure 42. Histogram window. 33

34 Figure 43. Event Statistics window. 34