Dr. Dobb's Journal - October 2007 - (Page 44)

State of the Art SOFTWARE AND THE CORE DESCRIPTION PROCESS continued from page 42 Sample Project 0.00 0.58 0.58 1.12 Example 1: PSICAT records the data model as an XML file. development of a custom drawing environment, no small task, but preserved the diagrams and drawing process the scientists were familiar with. It also had the potential to simplify the description process because the environment could be customized specifically to drawing core-description diagrams. The software could provide specialized tools for drawing geological features (like lithostratigraphic intervals) instead of forcing the scientist to represent these features with simple graphical objects (like rectangles and circles). The software and scientist could work at the same semantic level. Before I could begin work on the software, which would ultimately be called “Paleontological Stratigraphic Interval Construction and Analysis Tool” (PSICAT), I spent several months working directly with scientists to learn the specialized vocabulary, concepts, and requirements of core description. I reverse-engineered dozens of actual core description diagrams to determine what data was encoded in them and how the data was visually represented. I also observed the scientists actually describing core. Once I had a handle on the types of data and tasks involved, I began work on modeling these in software. Data Model Core description diagrams like Figure 1 display a wealth of different data. Many of the data types share common properties. For example, lithostratigraphic intervals and stratigraphic units each have an associated top and a base depth. Each data type also has unique properties—stratigraphic units have identifiers associated with them, whereas intervals do not. To accommodate these various data types and those that have not yet been identified, PSICAT (portal.chronos.org/psicat-site) required a flexible model and representation scheme for the data. Each high-level data type in PSICAT, such as lithostratigraphic intervals, stratigraphic units, and sedimentary structures, is represented by Model objects, which are associative arrays of key-value pairs. The associative array data structure was chosen 44 Dr. Dobb’s Journal l www.ddj.com l October 2007 http://portal.chronos.org/psicat-site http://www.pegasusimaging.com http://www.ddj.com http://www.pegasusimaging.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - October 2007

Cover Contents Hmmmm Alia Vox Developer Diaries Developer’s Notebook AI: It’s OK Again! Conversations Visual Cryptography and Bit-Plane Complexity Segmentation Inside the Windows Vista Disk Encryption Algorithm Memory-Aware Components Software and the Core Description Process Logging In C++ Effective Concurrency The Agile Edge Swaine’s Flames

Dr. Dobb's Journal - October 2007

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