Cavitation Imaging

You will need

• A cavicam that has completed the setup procedure. See Getting Started section for more information.

• A computer with wifi capability e.g. a laptop.

Step 1 - Access the caviconsole

See Accessing the Caviconsole for instructions.

Step 2 - Set to Capture Mode

From the Capture tab, set the Mode to Capture and click Update as required to save the change.

Note

For every settings change in the caviconsole, click the Update button.

Step 3 - Attach the Cavicam to the Sample

Loosen the grub screw on the collar and remove the camera assembly so that you can see inside the imaging chamber. Loosen - or completely remove - the side wingnuts so that the sample can be inserted between the top and bottom plates. Use the imaging chamber to position the sample and then tighten the side wingnuts to secure the sample in position. Careful not to overtighten and damage the sample.

Step 4 - Open Live Preview

From the Capture tab, click the Live Preview button to access a live feed from the camera.

In the live preview popup window, click Start Streaming to view the camera stream. Click the Light button to toggle the light on and off while streaming.

Can’t see a live stream?

If a broken image icon appears instead of the live stream, something is wrong with the camera. Usually this is because the camera ribbon cable connectors are not correctly connected. Check that the orientation of the silver connectors is correct and that the cable is fully inserted into the connector and locked in place with the hinge/clip. Check the Getting Started section for more information.

Step 5 - Focus

Re-attach the camera assembly and while watching the live preview, move the camera assembly up/down to focus and rotate left and right to optimise the angle of the image (if required). Tighten the grub screw to secure the top assembly in position. Don’t excessively tighten the grub screw.

Once the sample is in focus, click the Stop button to stop streaming from the camera and toggle the light off by clicking the Light button.

Step 6 - Choose Light Source

Light 1 or Light 2 will correspond to the top and bottom lights of the cavicam. To determine which is which, choose a light option, click the Update button and then toggle the light On using the Light button at the top right of the screen. As a general rule, leaves requires light shining through them (bottom light), while stems and other organs that don’t allow (much or any) light transmission require the top light.

Step 7 - Set Sequence Name and Storage Option

Set an appropriate sequence name. This will be the name of the folder that stores the images and data for the sequence.

Tip

Incorporating the date into the sequence name can be useful for differentiating between sequences and can help with storage management e.g. Eucalyptus_29072021

Choose an option for the Output Directory. To store images and data on the Pi (on the MicroSD card) use the /home/pi/captures option.

Choose the USB Stick option to store images and data on an external USB stick. Ensure that a USB stick is inserted into one of the USB ports.

Important note on USB sticks

USB sticks must be formatted in an appropriate format for the Raspbery Pi. See USB Stick Formatting for instructions.

Choose the resolution for images. In most cases, leave the resolution at the highest setting. Choose lower resolutions for smaller file sizes (at the cost of detail) and faster image processing offline.

Step 8 - Configure Shutterspeed

The shutterspeed setting determines the amount of light recorded by the camera.

Click the Preview button to generate an image using the current settings. Wait for the image to appear.

If the image looks too dark, increase the shutterspeed (by increments of 500-1000 is a good place to start).

If the image looks too bright and overexposed, decrease the shutterspeed.

After each adjustment, generate a new preview (by clicking the Preview button) and keep adjusting the shutterspeed in this fashion until reaching an optimum setting.

Step 9 - Set Duration and Interval

Set the capture Duration (total time to capture images) and capture Interval (time between captures) as required.

Note on the Interval setting

The interval duration is only applied once an image capture has completed. This means the interval does not take into account the time it takes to capture and save the image i.e. the time between image captures is the interval time +/- a few seconds and will never be precisely the interval time (the time it takes to capture an image is slightly variable).

Step 10 - Enable Cropping (as desired)

Enable the Crop function to capture just a section (i.e. ROI, Region of Interest) of the image.

Cropping the image saves memory for storage and makes post-processing (in ImageJ, for example) faster and less memory intensive.

Step 11 - Set the Pi Time

The Pi doesn’t keep time when turned off so the current time must be updated every time the Pi is turned on and before capture.

From the Util or Capture tabs click the Sync button to set the Pi time using the time on your computer.

Step 12 - Start Capturing!

Click the Start button on the Capture tab to initiate image capture.

Use the View Log button to check for issues and errors.

Next Steps

• Check out the user guide for accessing the images and data.

• OpenSourceOV.org for image processing guides.

• Check out the user guide for restarting after error.