The visualization infrastructure of CASA will be built out by completing pathfinder applications. These applications will build team knowledge and expand our codebase as we encounter new opportunities and challenges. Interactive clean is the first pathfinder application for the terminal usage setting. This is an important use case because it pushes the boundraries of what is possible in this usage setting.
For this use case, we had certain requirements that stretched the capabilities of Bokeh browser plotting:
two directional communication was necessary between Python and the interactive clean display in the web browser
state needed to be returned to the Python session where
Bokeh’s solution for the first issue is to serve the browser code from a
bokeh server process. Unfortunately, this python process is separate from the
tclean process, and interactive clean requires an ongoing dialog between
the imageing code in Python and the display the user interacts with in a browser.
To solve these problems, we introduced a WebSocket based infrastructure
to handle the update of browser display as
While we are only in the prototyping phase of the interactive clean application, we have prototyped a GUI that will go beyond what is currently possible with current implementations of interactive clean, as show in this figure:
The interactive clean application has three main panel groups: control group, configuration group, and visualization group. The control group provides interactive control of tclean allowing the user to step through the tclean process at the desired step resolution. Using the control panel, the user has options such play, pause, step, or stop as well as the ability to set properties such as the number of cycles , the interations, and the threshold value to use. A slider is also include that allows the user to cycle through the visualization for each channel in a smooth, responsive manner.
The configuration panel allows the user to set the minimal input parameters to tclean as well as displaying information about the image cube being used. In the future there are plans to add an advanced option to allow the user to access all of the tclean paramenters.
The visualization panels display the the current .image file as well as any masks that may be applied. For each tclean cycle information on the residual and total flux are displayed as well as histogram representing the spectral information at the current position when mousing over the image. All three displays are updated for each finished cycle. As mentioned previously the display for each channel can be accessed using the controls panel slider. There will be an option to scan and display different as well polarization in a future prototype.