Dragon (remote sensing)
Encyclopedia
Dragon refers to any of several remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...

 image processing
Image processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...


software packages. 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
derive from code created by Goldin-Rudahl
Systems, Incorporated, and focus on geography education:
  • OpenDragon is free to educational users. It was intended to be free worldwide, as well as open source
    Open source
    The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

     (hence the name) but due to funding problems, is currently available only in Southeast Asia.

  • Dragon Academic is functionally identical to OpenDragon.

  • Dragon Professional is expanded to handle full-scene data sets from sensors such as Landsat TM
    Thematic Mapper
    One of the Earth observing sensors introduced in the Landsat program. A Thematic Mapper was first placed aboard Landsat 4 , and one is still operational aboard Landsat 5. TM sensors feature seven bands of image data most of which have 30 metre spatial resolution...

    , SPOT
    SPOT (satellites)
    SPOT is a high-resolution, optical imaging Earth observation satellite system operating from space. It is run by Spot Image based in Toulouse, France...

    , and Aster
    Advanced Spaceborne Thermal Emission and Reflection Radiometer
    ASTER is a Japanese sensor which is one of five remote sensory devices on board the Terra satellite launched into Earth orbit by NASA in 1999...

    .

History

The initial version of Dragon was released in 1987 and ran on the MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...


operating system. Dragon was the first commercial remote sensing software
package designed to use only the native capabilities of off-the-shelf personal
computers. At the time Dragon was developed, other PC remote sensing products
such as Erdas
ERDAS IMAGINE
ERDAS IMAGINE is a remote sensing application with raster graphics editor capabilities designed by ERDAS for geospatial applications. The latest version is 2010, version 10.1. ERDAS IMAGINE is aimed primarily at geospatial raster data processing and allows the user to prepare, display and enhance...

 required expensive special purpose graphics
devices. Dragon was intended to be used for education in geography, geology,
forestry and other disciplines that use spatial information; thus it was very
important to minimize the costs of required hardware. The first version
of Dragon ran on a basic IBM-PC with two floppy disks and a
four-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 squeeze
functionality into very limited disk and memory space, and to get full-color
image display using rapidly changing graphics
hardware
Computer display standard
Computer display standards are often a combination of aspect ratio, display resolution, color depth, and refresh rate.This article describes the different display standards for computer displays.-History:...

 with no standardized drivers. The VESA
VESA
VESA is an international standards body for computer graphics founded in 1989 by NEC Home Electronics and eight other video display adapter manufacturers.VESA's initial goal was to produce a standard for 800×600 SVGA resolution video displays...

 display standard was a
turning point in making full-color display functionality available in
MS-DOS. This VESA/SVGA/MS-DOS version of Dragon can still be adapted
for embedded systems use.

The move to Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 95/98 was painful because these
operating systems did not provide true multitasking. Unfortunately this phase
coincided with the publication of the well-known Gibson and Powers textbook
(Gibson,2000) which included a copy of the Windows 95 Dragon. With the advent
of Windows NT and successors (Windows 2000, XP, Vista, etc), it became
possible to create a Windows version of Dragon that allowed simultaneous
display of and interaction with multiple images.

In 2004, funding became available from Thailand to create a free educational
version of the software which became known as OpenDragon. This project lasted
for 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 was
developed to reach beyond the customary educational users. New personal
computer capabilities, which by then extended to gigabytes of memory and
hundreds of gigabytes of disk storage, all at low cost, made it possible to
store and process the very large data sets produced by twenty first century
high 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 the
screen and the sensor data. At the same time, image processing operations such
as selection of ground control points require access to individual data
elements (pixels) selected from the more than 30 million available in a
typical full-scene image. Thus, the appearance and behavior of Dragon
Professional are quite different from OpenDragon/Dragon Academic.

The name

Asian dragons are considered symbolic of wisdom and knowledge, unlike the
ferocious western dragons. Thus, the name Dragon/ips(r) or Dragon Image
Processing System is intended to imply wisdom in the knowledge of and
intelligent use of the world in which we live.

The Software

Because the expected user is assumed to be relatively untrained, Dragon pays
more attention to the user experience than to having a large selection of
possibly obscure processing operations. Within the user interface, which has
been translated into several languages, context-sensitive help explains every
user choice, and reasonable defaults are provided where possible. The User
Manual (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 to
know. These include:
  1. Single and multiband image display;
  2. Filtering for image enhancement;
  3. Band combinations such as sum and ratio;
  4. Principal components analysis;
  5. Image statistics and measurement;
  6. A variety of supervised and unsupervised classification algorithms;
  7. Registration and geometric correction;
  8. Heads-up digitizing to capture vector data;
  9. Some raster geographic information systems GIS
    Geographic Information System
    A geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data...

     operations such as slope, aspect, and buffer calculations;
  10. Import from and export to various standard image file formats such as GeoTIFF
    GeoTIFF
    GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for...

    .


In order to provide interoperability with other software packages, and to permit users
to add their own custom processing operations, all important file formats are
documented and an API called the Programmer's Toolkit is available.

Problems

  1. Dragon Academic and Dragon Professional use a USB dongle for copy protection. While this allows the license to permit unlimited copying, it is also sometimes inconvenient. Other protection methods are being considered.
  2. Supervised and unsupervised classification operations in all versions of the software currently can process only four image bands at a time.
  3. Dragon can measure length and area on any georeference
    Georeference
    To georeference something means to define its existence in physical space. That is, establishing its location in terms of map projections or coordinate systems. The term is used both when establishing the relation between raster or vector images and coordinates, and when determining the spatial...

    d image. However this assumes the image uses a distance-preserving projection. If the image uses latitude-longtitude
    Geographic coordinate system
    A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers. The coordinates are often chosen such that one of the numbers represent vertical position, and two or three of the numbers represent horizontal position...

    , the measurements will be incorrect in high latitudes.
  4. The software runs only on Microsoft Windows, although three of its four components also build and run on Linux
    Linux
    Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

    .

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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