Dynamic Queries cs5984: Information Visualization Chris North

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Limitations Scale: Scatterplot screen space: 10,000 – 1,000,000 Data structures & algorithms: < 50,000 –Poor screen drawing on Filter-out A Solution: Query Previews! “AND” queries only Arbitrary boolean queries? A solution: Filter Flow

DQ Algorithm Idea: incremental algorithm only deal with data items that changed state When slider moves: Calculate slider delta Search in data structure for data items in the delta region If slider moved inward (filter out): –Erase data items from visualization Else slider moved outward (filter in): –Draw data items on visualization Problem! Overlapped items, erases items underneath too

DQ Data Structures (1) Sorted array of the data for each slider Need counter for each data item = # sliders that filter it Attribute Explorer visualizes these counters too! O(delta) Year: Delta

DQ Data Structures (2) Multi-dimensional data structure E.g.: K-d tree, quad-tree, … Recursively split space, store in tree structure Enables fast range search, O()

DQ Data Structures (2) Multi-dimensional data structure E.g.: K-d tree, quad-tree, … Recursively split space, store in tree structure Enables fast range search, O(logn) Delta

Erasure Problem Each pixel has counter = number of items Can visualize this for density! Z-buffer? Redraw local area only

Filter-Flow Betty Catherine Edna Freda Grace Hilda Judy Marcus Tom

Influence/Attribute Explorer Tweedie, Spence, “Externalizing Abstract Mathematical Models” (Influence/Attribute Explorer) Z.Wang, Ali

Query Previews Doan, “Query Previews” Anuj, Vikrant

Thurs Book chapter 9 Thurs: Multi-D Functions Feiner, “Worlds within Worlds” » sandip, ben vanWijk “HyperSlice” » kumar, kunal

Next Week Tues: 1-D Plaisant, “Lifelines” » mahesh, jon Eick, “SeeSoft” » jeevak, alex Thurs: 1-D Mackinlay, “Perspective Wall” » ahmed, ganesh Hibino, “MMVIS” » atul, dananjan

Project Proposal Project list… Due thurs Team members Project idea Schedule

Presentations Use pictures, pictures, pictures, pictures, … Use text only to hammer home key points What’s the take-home message? ~2 main points Motivate! In class: Goal 1: understand visualization (mapping, simple examples) Goal 2: strengths, weaknesses, scale, HCI metrics, “insight” Time is short: 10 min = ~5 slides, practice out loud

Implementation detail crap The first step of processing requires the construction of several tree and graph structures to store the database. System then builds visualization of data by mapping data attributes of graph items to graphical attributes of nodes and links in the visualization windows on screen. More boring stuff nobody is ever going to read here or if they do they wont understand it anyway so why bother. If they do read it then they most certainly will not be listening to what you are saying so why bother give a talk? Why not just sit down and let everybody read your slides or just hand out the paper and then say ‘thank you’. This person needs to take Dr. North’s info vis class.

Discusser Ask questions: what do you think about this visualization? scale Good, bad? Comparisons to other vis Improvements Have some possible answers Spark controversy!