Dragon is a remote sensing image processing software package. This software provides capabilities for displaying, analyzing, and interpreting digital images from earth satellites and raster data files that represent spatially distributed data. All the Dragon packages are derived from the code created by Goldin-Rudahl.
The initial version of Dragon was released in 1987 and ran on the MS-DOSoperating system. Dragon was the first commercial remote sensing softwarepackage designed to use only the native capabilities of off-the-shelf personalcomputers. At the time Dragon was developed, other PC remote sensing productssuch as Erdas required expensive special purpose graphicsdevices. Dragon was intended to be used for education in geography, geology,forestry and other disciplines that use spatial information; thus it was veryimportant to minimize the costs of required hardware. The first versionof Dragon ran on a basic IBM-PC with two floppy disks and afour-color or gray-level graphics display. Alternatively, it could use any of several models of Japanese PC.
The MS-DOS phase of Dragon development focused on trying to squeezefunctionality into very limited disk and memory space, and to get full-colorimage display using rapidly changing graphicshardware with no standardized drivers. The VESA display standard was aturning point in making full-color display functionality available inMS-DOS. This VESA/SVGA/MS-DOS version of Dragon can still be adaptedfor embedded systems use.
The move to Microsoft Windows 95/98 was painful because theseoperating systems did not provide true multitasking. Unfortunately this phasecoincided with the publication of the well-known Gibson and Powers textbook(Gibson, 2000) which included a copy of the Windows 95 Dragon. With the adventof Windows NT and successors (Windows 2000, XP, Vista, etc.), it becamepossible to create a Windows version of Dragon that allowed simultaneousdisplay of and interaction with multiple images.
In 2004, funding became available from Thailand to create a free educationalversion of the software which became known as OpenDragon. This project lastedfor three years. The software is still available at no cost in Thailand,Laos, Cambodia and Vietnam (although it has only been translated into Thai).
After funding for OpenDragon was discontinued, Dragon Professional wasdeveloped to reach beyond the customary educational users. New personalcomputer capabilities, which by then extended to gigabytes of memory andhundreds of gigabytes of disk storage, all at low cost, made it possible tostore and process the very large data sets produced by twenty-first-centuryhigh-resolution satellites.
Dragon Professional required major changes in the user interaction model,which previously had assumed a 1-to-1 relationship between the image on thescreen and the sensor data. At the same time, image processing operations suchas selection of ground control points require access to individual dataelements (pixels) selected from the more than 30 million available in atypical full-scene image. Thus, the appearance and behavior of DragonProfessional are quite different from OpenDragon/Dragon Academic.
Asian dragons are considered symbolic of wisdom and knowledge, unlike theferocious western dragons. Thus, the name Dragon/ips(r) or Dragon ImageProcessing System is intended to imply wisdom in the knowledge of andintelligent use of the world in which we live.
Because the expected user is assumed to be relatively untrained, Dragon paysmore attention to the user experience than to having a large selection ofpossibly obscure processing operations. Within the user interface, which hasbeen translated into several languages, context-sensitive help explains everyuser choice, and reasonable defaults are provided where possible. The UserManual (English only) details all processing algorithms.
The software provides a fairly conventional set of remote sensing operations,which are intended to be those which a student of geography arguably ought toknow. These include:
In order to provide interoperability with other software packages, and to permit usersto add their own custom processing operations, all important file formats aredocumented and an API called the Programmer's Toolkit is available.