Thursday, October 06, 2005

GTViewer's Highlight By Phase Application

The next several posting will cover various applications that use GTViewer as an application development platform. The last application discussed was the Upstream/Downstream Trace and it showed how a sophisticated GIS application can be implemented. This posting will cover another application that is much simpler in its design, but is still very useful. The Highlight By Phase app really does not do anything different from what you can already do with GTViewer and its built-in Thematic Queries; however, this app streamlines the use of several Thematic queries at once and minimizes the user’s input to get a standardized set of results.

The Highlight By Phase app allows the users to highlight electrical features that have a particular phase attribute. The standard app allows the user to select A, B, C, or Multiple. If A is selected, all features with the phase attribute set to A will be highlighted in Red. If B is selected, all features with the phase attribute set to B will be highlighted in Blue; and if C is selected, they will be highlighted in Green. A forth option allows features with more than one phase to be highlighted in Orange. By pressing the Highlight button, the Emphasize Session Graphics mode is engaged (to gray out all of the features), and the selected Phases are highlighted in the appropriate colors. The Highlight By Phase app only applies to features that are in the current view; however, there is no limit as to how many features you can include in the view, other than the more features, the longer it will take to process. Fortunately, GTViewer can process highlighting very fast and a very large number of features can be processed in this manner.

Sample Output using Emphasize Session Graphics Mode:

Sample Output with a Raster Backdrop:

To fully appreciate how valuable this simple little app can be, let us compare it to what would be done with Thematic Queries. A Thematic Query in GTViewer highlights a set of features with common attribute values, such as all wooden poles, all conductors with a particular circuit id, or all electrical features with a specific phase attribute. The Thematic Query is generic; the users fill in the prompts like a standard query to select the features to highlight, then the user selects how the highlighted items will appear (color, weight, etc.). The Highlight By Phase app is really just performing 4 Thematic Queries at once (A, B, C, Multiple) with a preset color scheme.

Just like with the Upstream/Downstream Trace, once results are obtained, the user can do various things with them. The results can be Printed as shown below:

The results can be converted to Redlines with the Tools/Highlighted Elements to Session command. Once converted to Redlines, the results can be shared with other users, manipulated, or exported as a DGN file or XML.

The Highlight By Phase app’s logic can be applied to many tasks other than phase highlighting. It can contain a list of predefined Thematic queries for any discipline, it can contain more preset Thematic Queries to choose from, and it can base its feature select on much more complicated criteria than a single attribute.

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