Contents
Here is the imagehub.yaml file where all the options have been specified:
# Settings file imagehub.yaml -- example with all settings --- hub: queuemax: 500 # maximum size of the memory queue of images to write patience: 68 # how many minutes before logging a "no messages" event print_settings: False data_directory: imagehub_data max_images_write: 9000 # a cap on images to write in one day
The imagehub.yaml settings file is expected to be in the users home
directory by default. You can specify the path to a different directory
containing imagehub.yaml by using the optional argument --path:
workon py3cv3 # use your own virtual environment name
python3 imagenode.py --path directory_name # directory holding imagehub.yamlThere is an example imagehub.yaml file in the main repository folder. It is
the same as the file shown above. To use the file, copy it to the home
directory and edit it there. That way you can keep the example file unchanged
for future reference.
The imagehub list of options is much smaller than the imagenode list.
Settings follow YAML conventions. The settings are dictionary key value pairs. For example:
queuemax: 500
The example imagehub.yaml file shows how the settings are arranged. There is no error
checking of the settings; if a setting is not set to an expected value, then
a Python traceback error will result. This is adequate for debugging issues
with settings (misspelling a setting name, etc.) and saves writing a lot of
deeply nested if statements. You can also specify an option in the settings
to print the settings; this can be helpful in spotting option misspellings, etc.
There are 5 optional settings available:
queuemax: 500 # maximum size of the memory queue of images to write patience: 5 # how many minutes before logging a "no messages" event data_directory: imagehub_data max_images_write: 9000 # a cap on images to write in one day print_settings: False
The queuemax option sets a size on the image writing queue in memory. If
not specified, the default is 500. You will only need to specify a smaller
number if you are running out of memory.
The patience setting sets the maximum number of minutes for imagehub
to wait for an event reported by a sending imagenode. If there has been no
event or image received in in that number of minutes, a "no messages received"
event will be placed in the log. This is helpful for debugging communications
issues, which are usually caused by an incorrect hub address specified by
an imagenode. Exceeding the patience time will not end the program, it
will just put an event into the log after the specified amount of time.
The data_directory setting sets the name of the directory where the images and
event logs will be stored. The default is imagehub_data in the home directory.
The max_images_write option is a "safety" option to prevent filling a disk
with unintended images. For example, if an imagenode is (unintentionally) set
to send images option continuous, then the number of images received and
saved could rapidly fill a disk drive on the hub. I know this from a my own
bad experience when I forgot to change the continuous option to detected
event on one of my RPi nodes.
The max_images_write option is the most important option and the most difficult
to explain. imagehub starts a new image directory each time the date changes.
So, the max_images_write parameter is set to 0 each time a new directory is
created. And the image_count in incremented each time an image is written. When
image_count exceeds max_images_write, there is no more writing in that directory.
Writing resumes when a new directory is created (normally when the date changes).
The default is 9000 if you don't specify an option.
The print_settings option allows you to print the options that were read
by the imagehub program to check spelling etc. The default is False.