Common and Webcam

Hardware cameras

OpenHSI Hardware Camera Implementations

Common Code

Tip

This module can be imported using from openhsi.cameras import *

Wrapper class and example code for getting images from the OpenHSI.

Tip

To use the camera, you will need some calibration files. You can also generate these files following this guide which uses the calibrate module.

To add a custom camera, five methods need to be defined in a class to: 1. Initialise camera __init__, and 2. Open camera start_cam, and 3. Close camera stop_cam, and 4. Capture a picture as a numpy array get_img, and 5. Update the exposure settings set_exposure, and 6. [Optional] Poll the camera temperature get_temp.

By inheriting from the OpenHSI class, all the methods to load settings/calibration files, collect datacube, saving data to NetCDF, and viewing as RGB are integrated. Furthermore, the custom camera class can be passed to a SettingsBuilder class for calibration.

For example, we implement a webcamera camera below.

Webcams

This uses the OpenCV library to interface with a webcam including the one in your laptop. Mainly for testing but maybe this could be useful.

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source

WebCamera

 WebCamera (mode:str=None, n_lines:int=16, processing_lvl:int=-1,
            warn_mem_use:bool=True, json_path:str=None, cal_path:str=None,
            print_settings:bool=False)

Interface for webcam to test OpenHSI functionality

You can see a picture I held up to the webcam.

plt.subplots(figsize=(12,4))
plt.imshow(cam.dc.data[:,1,:],cmap="gray",aspect=0.3)

Function for collection/saving linked to button

This function is designed to be used using the Multiprocessing library to initiate camera recording when desired inside a script. When the switch is closed, this function then finishes releasing memory back to the system.

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source

switched_camera

 switched_camera (cam_class:str=None, n_lines:int=128,
                  processing_lvl:int=0, json_path:str='/media/pi/fastssd/c
                  als/flir_settings.json', cal_path:str='/media/pi/fastssd
                  /cals/flir_calibration.pkl', preconfig_meta:str='/media/
                  pi/fastssd/cals/preconfig_metadata.json',
                  ssd_dir:str='/media/pi/fastssd', toggle_interface=None)

If toggle_interface.status is True, collect with the camera until switched is False.

	Type	Default	Details
cam_class	str	None	Camera Class Name from openhsi.cameras
n_lines	int	128	how many along-track pixels
processing_lvl	int	0	desired processing done in real time
json_path	str	/media/pi/fastssd/cals/flir_settings.json	path to settings file
cal_path	str	/media/pi/fastssd/cals/flir_calibration.pkl	path to calibration file
preconfig_meta	str	/media/pi/fastssd/cals/preconfig_metadata.json	path to metadata file
ssd_dir	str	/media/pi/fastssd	path to SSD
toggle_interface	NoneType	None	toggle_interface that controls collection