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Weekly Report - 29/11/13




Further to my simple event marker implementation (showing "signpost" markers above the plot area of a graph, along with the vertical lines currently used to mark events), I set out to determine the best way to draw these markers and lines so that they would be clearly visible but not so much as to obscure or draw attention away from the plot. One particular challenge was to be able to guage the severity of the event at a glance, which is currently done by colour (yellow/orange/red) but to avoid conflicting with colours used by series on the plot. One solution for this I tried was to prevent graph styles using any colours in a particular hue range (so as to avoid yellow-red which would be used by the events) but due to both the events and plot being in colour it still made it confusing to tell which were which.

After much very scientific experimentation in the field of colour perception I found that plots drawn with the same saturation or lightness appeared to be related, and changing the hue divided this related group further; it was easiest to tell event markers apart from data when one of these groups was drawn with a different level of saturation, regardless of hue. The obvious conclusion therefore was to draw one group at 0% saturation and the other at 100%, for maximum differentation. As such, the data plot is drawn at 100% saturation with any hue, the event lines are drawn grey and the event markers are still drawn with colour where they will not detract from the plot.

For the rest of the week I have been looking at reproducing (to some extent) the AMP traceroute map in Cuz using Flotr2. I've been familiarising myself with old code and researching alternative representation methods, such as directed graphs, as the data we want to visualise is not necessarily a tree, although we want to view the data in a tree-like form and we may not want the nodes to be as interconnected as they would be in a graph. While I've been thinking about this I've created a graph type that can draw static plots while moving through time and I'm going to start drawing things in it next week.