At the 2018 DM-SE mini-JTM, there was a session "DM/SE visualization discussion for commissioning". As it turned out, an hour of the session ranged rather widely across visualization use cases across the whole of development, commissioning, and early operations.
Below is a list of the use cases, transcribed from the whiteboards in the meeting room. In the coming days the intent is to expand on these use cases by adding information that clarifies the use cases, describes whether they are pure visualization requirements or involve LSST-specific analytics, and how these might be - or already are - addressed by the Science Platform SUIT components or by other libraries or systems (e.g., matplotlib, Bokeh).
| Use case key topic (from original whiteboard) | Initial clarification |
|---|---|
| Visualization of all-sky "stuff" (a/k/a statistics, e.g., MAF metrics) | This is the display of quantities that are evaluated across the entire (LSST-observed) sky and are desirable to be able to explore at a range of scales from all-sky down to the finest-grained level at which they are defined. |
| Collections of thumbnails | Meant to be around a designated set of objects or sources (if sources, this could be a time-dependent selection of apparitions of the same object). |
| Brushing and linking between scatter plots and thumbnails | Could mean: use brushing and linking to select the sources around which to request thumbnails, or: use brushing and linking to narrow the displayed set of thumbnails from an already-requested set. |
| Extensible displays | Because the set of interesting specific visualizations far exceeds what could be provided centrally, make it possible for users to define visualizations, constructed from the lower-level visualization capabilities in the system (or an external library), in a way that makes them straightforward to apply on demand. |
| Turn on and off sources based on flags (i.e. with checkboxes) | These flag selections are meant to participate in whatever more general brushing and linking environments are provided - e.g., to permit sources/objects with designated flags to be shown or hidden in, say, a color-color plot or in an overlay over an image. |
| Quick access to schema descriptions | (Gregory Dubois-Felsmann doesn't remember exactly what was meant when this was raised in the meeting; the following is a guess.) |
| "Standard" image interactions in a responsive way: scale, stretch, zoom, pan, colormap | There was a general desire for stretch/scale changes to be "fast". In the meeting we discussed at least three different interpretations of color mapping: rendering of single-channel image data with a color that depends on the flux value (or whatever other variable is represented by the pixel values); rendering of single-channel image data with a hue or a partially transparent color overlay based on an additional channel; generation of color from 3 independent channels. For future purposes we'll treat this use case as referring only to the first of the three; the other two have their own use cases below. |
| On-demand pixel-level colorized images | Generation RGB color images based on the combination of three single-channel images (at a minimum: single-channel images with precise registration with each other, but it need not be limited to this). Both the "traditional" and the "hue-preserving" algorithms should be supported. |
| Colorized overlays on greyscale images (with tunable alpha) | This refers to the rendering of single-channel image data with a hue or a partially transparent color overlay based on an additional channel (e.g., colorizing a single-channel flux image by the per-pixel variance). Note that mask-overlay display could be treated as an instance of such a capability, but for tracking purposes we'll treat it separately. |
| Crossfading between images | Using a slider, allow the continuous variation of what is displayed based on two over-plotted images of the same region (whether in sky or x-y coordinates), moving from displaying one or the other image through displaying a superposition of the two. Alternatively, using a slider or a movable "curtain" UI element to wipe one image across the other. |