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Software Review

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Earth Version 2.0
Reviewed by: Thomas R. Allen, Dept. of Political Science and Geography, Old Dominion University, Norfolk, Virginia 23529-0088 e-mail:Tallen@odu.edu
(reprinted from PE&RS October 2002)

Product Information 

Vendor
Pixoneer Corporation
7777 Leesburg Pike, Suite 7LS
Falls Church, VA 22043 USA
703-852-2162,
1-866-PIXONEER,
703-852-2170 (fax)
www.pixoneer.com
info@pixoneer.com

Hardware
Minimum Requirements:
Pentium II
64/128 Meg RAM
10/20GB Hard Drive
8 MB Graphics Card
Minimum Screen Resolution 800 x 600

Hardware Platforms Supported:
Intel Pentium or any 100% compatible computer (Pentium II with MMX, Pentium III, Pentium IV, Pentium Pro, AMD, and Cyrix)

Software
Software runs on Windows 98, Windows ME, Windows NT, and 2000
Program file size ~ 130 Meg

Tested Configuration

1.7Mhz Pentium IV with 1.0GB RAM
3Dlabs Wildcat II 5110 graphics card
Windows 2000 (sp2)

Summary
Earth 2.0 from Pixoneer, Corp. is an image processing software package for integrated image interpretation and analysis. The software offers an easy-to-learn, icon-based interface with a diverse suite of data management, analysis, and output functions. The software contains numerous modules for the integration of geospatial data from remote sensing, GIS, or GPS sources. Provided preprocessing tools are comprehensive, including georectification, orthorectification, atmospheric and radiometric normalization, topographic correction, and synthetic aperture radar (SAR) analysis. Mainstream image classification algorithms, including supervised and unsupervised classification and editing capabilities are also incorporated. Image enhancement tools include image sharpening, spectral and color transformation, image algebra and band math, and spatial and frequency filtering. Data import/export tools are provided for other popular products such as ESRI ArcGIS© and ArcView©, Erdas IMAGINE©, ER Mapper©, ENVI©, and PCI©. In addition, raw satellite image formats, GIS data, and generic binary and ASCII import/export are available. Image manipulation and management tools allow users to subset, mosaic, and composite scenes. A 3D viewer provides for integration of terrain modeling and remote sensing, including fly-thru visualization and orthographic perspectives with raster and vector overlays. Map production tools are packaged in a provided module, “iMapper.” Overall, the software provides the tools for comprehensive image analysis from input, preprocessing, enhancement, classification, visualization, and output.

The Earth 2.0 software is available for trial use from the vendor by download or CD-ROM upon request. This review tested a standard installation of the software using the provided sample data and tutorial. In addition to these items, Pixoneer supplies a comprehensive online help manual, user manual, and a forthcoming set of educational modules for training. They also provide technical support and publish a newsletter for users. To evaluate the robustness and versatility of the software, external data in the author’s possession was also imported and used to evaluate Earth 2.0.

Features
The focal point of the Earth 2.0 interface is an icon-based menu window with buttons for accessing modular submenus and analysis functions. Each module of the software is accessed from the main menu (Figure 1.) Each module has its own set of icons for using the relevant dialog boxes and tools. Most image display and interpretive functions of the software are accessed in the Visual Analyzer window (Figure 2.)

Figure 1. Earth main menu window

 

Figure 2. Visual Analyzer window with image file loaded (daejon.idm).

Other submenus reflect the diverse analytical tools of the overall package, including below:

  • Image Processing
    • Preprocessing Functions
      • Geometric Correction
      • Orthorectification
      • Radiometric Normalization
      • Topographic Correction
    • Classification
      • Supervised Classification
      • Unsupervised Classification
      • Feature Extraction by spectral and spatial reflectance
    • Classification Editing
    • Vectorization and GIS import/export
    • Image Enhancement
      • Image Sharpening
      • Spectral and Color Transformation
      • Image Algebra and Band Math
      • Spatial and Frequency Filtering
  • DEM Tools
    • Stereo DEM generation and updating
    • SAR image coregistration
    • SAR interferogram generation and filtering
    • SAR DEM generation
    • Vector DEM rasterization
    • DEM editor and interpolation
    • DEM topographic modeling
  • SAR Tools
    • Header viewer
    • SAR backscatter and db analysis
    • Slant range and ground range extraction
    • Antenna pattern correction
    • Spatial and frequency filtering
    • 3D Analyzer
    • Scale tools
    • Color palletes and histogram control
    • 3D views
    • Flying simulation
    • Path and Line-of-sight analysis
    • Background illumination
    • Annotation and vector overlay
    • BMP and AVI movie recording, export, and play
  • iMAPPER Map Tools
    • Interactive image map import or creation from Visual Analyzer
    • Graticule and scale bar tools
    • Legend editor
    • Color bars and north arrows
    • Annotation and text
    • WYSIWYG printing

Image Display
The Visual Analyzer provides a comprehensive set of tools for image display, including handy on-screen windows for layer organization and band-color assignment as well as display of ground control points (GCPs) and regions of interest (ROIs.) The Visual Analyzer works with IDM file format, a generic BSQ (band sequential) binary format that can contain up to 256 bands with no size limit. Each IDM file has a paired IDX file containing ancillary information (sensor, bands, coordinates of the image, and such header information.) A status bar in the viewer shows coordinate locations and pixel values as well as the stretched screen display value. Quick enhancements are accomplished easily from a pull-down menu on the viewer. These include on-the-fly linear min-max stretches, Gaussian, and histogram equalization. Viewer zoom tools are also positioned along the top of the icon bar. One handy feature in the viewer is a toggle button for a scale bar in the viewer. In the lower left of the Visual Analyzer, a magnifier window (scroll window) is positioned to allow the magnification of cursor areas or to set the zoom. A layers contents list appears at the upper left of the Visual Analyzer for quick manipulation of layer color gun assignments and display of GCPs and ROIs.

In addition to pure display manipulation, the Visual Analyzer window provides buttons along the icon bar for image statistics and file size and structure, scattergrams, measurement tools, and selection tools for GCPs and ROIs. Multiple viewers with co-registered images may also be linked spatially, especially useful in classification and interpretation, with simple execution of a Link View button. The structure of the visual analyzer is quite efficient, because it provides the most commonly used tools in conjunction with visual analysis without the need for navigating extensive pull-down menus or dialog boxes. The only caveat to the new user is that the interface provides icons without the redundant or optional use of a menu bar. Use of the analyzer window improves rather quickly with practice since the button icons use visually-keyed graphics. The overall result is an ergonomically efficient image analysis window that maximizes the available desktop space and makes viewing and interpretation easy for the learner and efficient in production and research applications.

Image File Management
Earth 2.0 provides a slate of image file management and manipulation tools. All file management tools mentioned are accessible from the main menu “Tools and Utilities” submenu. Vital image import and export functionality includes common image formats and some of special value to the scientific and engineering community. The file information tab in the Visual Analyzer and corresponding tool in the Tools and Utilities menu provide access to image statistics, scattergrams, and a header editing dialog. Image import supports five general categories of images with specific file formats in each group. Satellite image formats pre-programmed include AVHRR, ERS, IKONOS, IRS FAST, JERS-1, KOMPSAT, LANDSAT (CEOS, FAST, HDF, MRLC, and NDF formats), RADARSAT, and SPOT). HDF format is generic and allows import from various HDF-formatted sensor data (e.g., Landsat, MODIS, ASTER, MISR, CERES, and MOPITT.) Remote sensing imagery file formats include several common software formats (ArcView© raster, ENVI©, Erdas© .IMG and .LAN, and ERMAPPER© .ERS, and PCI© .PIX). Digital Elevation Model (DEM) format importers include USGS DEM and STDS (Spatial Data Transfer Standard), DMA DTED, and Lidar X,Y, Z. The latter format opens a convenient dialog for specifying output file resolution, size, and “no data” values. The list of export image formats includes Erdas 7.5 .LAN (but not .IMG), PCI (.PIX), ERMAPPER (.ERS), ENVI, and ArcView binary BIL. A set of generic binary and ASCII output formats are also supported, including BIP, BIL, and BSQ formatting. Finally, the export utility also provides for TIFF and GeoTIFF formats as well as on-the-fly image subset for export, including specifying a rectangular region of interest to subset or band selection.

Prime image management utilities in Earth 2.0 include subset/resize images, mosaic, layer manipulation, and map projection conversion. Subsetting images is accomplished using a single dialog box from the submenu button bar. This function supports three kinds of georeferencing, nearest neighbor, bilinear interpolation, and cubic convolution. The subsetting functionality here only supports rectangular regions of interest. Mosaic processsing is subdivided into spatial and spectral manipulation. Spatial mosaic refers to the common task of integrating adjacent and/or overlapping imagery or raster GIS data into a combined file. Two kinds of spatial mosaic are included — georeferenced automatic positioning or manual pixel-based selection (for non-georeferenced images.) A special histogram adjustment tool can be enabled within the software to adjust contrast for matching adjacent images in areas of overlap. Map projection conversion is accomplished in a single window interface from the “Tools and Utilities” submenu. A powerful and straightforward tool, the projection conversion works with most projections, coordinate systems, and datums in contemporary use. Projection conversion allows either image warping or point-by-point conversion. Over 250 projections and datums are supported in this version, including a conversion utility for point re-projection. In addition to re-sampling by nearest neighbor, bilinear interpolation, and cubic convolution, the coordinate conversion dialog allows on-the-fly subset and band selection. For correction of badlines, line dropouts, “pits” in DEMs, or other errors in raster data, the “Tools and Utilities” menu contains a Pixel Editor. This tool provides easy access to the actual pixel data to correct individual pixels, bad lines, or portions of lines, and assists their correction with pre-programmed averaging and user-specified substitution options.

Two rather unique aspects of the Tools and Utilities in Earth 2.0 may interest select users. One button on the menu provides an algorithm for estimation of sun angle from user-specified inputs (date, time, latitude, longitude) for calculation of solar elevation and azimuth angles. This utility can be handy, for example, in change detection and topographic normalization or classification work. Another interesting utility is a button for hyperlinks to Earth Observation imagery, the “EO Imagery Search” button. This activates a window with hyperlinks and a browser activation tool to connect and search several digital satellite image providers. The tool has functions to update and customize these links and lists common sensor resolutions and spectral-orbital characteristics. With the advent of numerous and ever-growing sensors, this utility could be very useful to new users and those involved with diverse multisensor projects.

Image Processing and Classification
Image processing and classification functions are integrated in the “Image Processing” submenu of Earth 2.0. These functions include fundamental preprocessing and classification functions, such as geometric correction (with GCP selection and editing), radiometric and topographic correction, orthorectification, supervised and unsupervised classification, feature extraction, and band math. Spectral and spatial filtering algorithms, a classified image editor, and vectorization button are also packaged in this menu interface. The GCP (ground control point) Geometric Correction tool allows selection or input of GCPs from keyboard entry, selection from other rectified imagery, or from digital vector maps. The user can save and modify GCP sets in both the input image and a reference file in the case of master/slave rectification. Image transformation tools, including multispectral enhancement and color transforms, are grouped into a single interface.

Unsupervised classification provides sequential, k-means, and ISODATA algorithms. The parameters for each algorithm follow published literature, such as specification of the number of clusters, merger and splitting of clusters by size thresholds, and maximum number of iterations. Cluster centroid distances and means are reported iteratively as well as in the final output stage. The functionality allows the user to run algorithms in spatial subsets or to specify a select set of input bands.

Supervised classification incorporates six algorithms: minimum distance to means, parallelpiped, Mahalanobis, maximum likelihood, spectral angle mapper, and neural network classification. For all methods, interactive training set creation and editing is incorporated. Scattergrams are visible within the same window as principal editing and signature evaluation tools. The included artificial neural network classifier is based on a backward-propagation algorithm and includes three layers (input, hidden, and output) with user-specified options including number of input nodes and layers, and output classes.

Other functionality in the image processing menu includes band math/algebra calculations, radiometric and topographic correction, multispectral image transformation, and spatial sharpening. Band math tool uses a calculator-like interface to allow the user to derive multispectral pixel variables. The interface has a built-in conditional rule with a if-then-else rule structure. The tool allows algebraic calculation with multiple input images. Radiometric correction tools included in Earth 2.0 are based on relative or normalization of multitemporal images. The method uses the same toolset for GCP collection to allow the user to select radiometric control points (e.g., “stable reflectors”) or other selection technique. A first-order polynomial regression, visible in a separate window, is derived and applied to correct the subject image to a reference scene. Topographic normalization tools include cosine correction, statistical-empirical normalization, C correction, and Minnaert constant correction. With the built-in sun angle ephemeris calculator, the technique is quite easily applied. Image sharpening is a tool for spatial resolution enhancement for combining a high-resolution panchromatic sensor with a multispectral RGB image. Intensity-hue-saturation (IHS) and Brovey transform algorithms are included. Overall, the image processing analytical tools are quite a diverse and powerful set of tools not widely available in commercial software.

3-Dimensional Analysis
Three-dimensional perspective and orthographic displays can be visualized and manipulated in the iTier 3D Analyzer of Earth 2.0. The single window interface provides all the tools needed to display 3D topography, drape imagery and vector data, 3D objects. Advanced functionality in this analyzer includes flowpath analysis, line-of-sight (LOS) analysis, and 3D fly-thru and movie loop generation. Sky and background colors and illumination can be customized by the user. Default movie generation is .AVI files, and MPEG and Microsoft video codec compressors are also supported. Flight paths can be digitized and preset before recording the animation. Flight controls include interactive and path-based flights, terrain contour-following, visible radius, look angle, and altitude controls, and scaling factors for image and topographic resolution detail. Figure 3 shows a snapshot view in the 3D Analyzer window.

Figure 3. 3D topographic visualization with image drop on a DEM.

Map Generation
The iMapper module of Earth 2.0 is the tool for map composition and output. The iMapper tool is accessible directly from the Visual Analyzer window or from the Earth Main menu. The object-based WYSIWYG (what-you-see-is-what-you-get) interface is intuitive and efficient for rapid image map production and customization. The iMapper allows easy placement of the image map and a single properties interface for specification of scale, display resolution, draw order of pixel and vector data (if present), and coordinate range of output. In the iMapper icon bar, tools for the map grid (graticule), scale bar, legend, north arrow, color bar, and other images (e.g., inset or multiple image maps in a composition.) The grid/graticule tool is exceptionally easy to use and includes tabs for displaying grid, latitude/longitude, and pixel row/column coordinate locations. Annotation tools include text and text boxes and vector drawing tools. Six north arrow styles are included in the interface. Legend fills include solid and patterned textures and customizable descriptions. The color bar tool is a convenience for depicting the ranges and adding text descriptions for continuous image variables (e.g., reflectance, elevation, bathymetry, or NDVI.) Figure 4 shows a sample image map composed in iMapper for Norfolk, Virginia, USA using a Landsat-7 ETM+ image (bands 5,4,3 RGB.) The iMapper module includes several different alignment options, a print preview, and tile processor for large maps. Maps can be exported to JPG, TIFF, and BMP at resolutions from 72dpi to 1200dpi.
Figure 4. Sample image map of a Landsat ETM+ subset of Norfolk, Virginia, composed in Earth 2.0 iMapper map generation module.

Performance and Operability The software was installed on two platforms running Windows 2000 sp2, a Dell Performance 300 desktop PC with 1700 Mhz Pentium IV and 1GB RAM and a Gateway 9500 laptop with 1400Mhz Pentium IV and 256MB RAM. In both cases, the software performed at a high level. Pixoneer Corp. provided the software and associated help files, tutorial, and sample data on cd-rom. In addition, the software was downloaded and installed for evaluation on the laptop PC from Pixoneer’s website for the 30-day free trial (http://www.pixoneer.com/). The speed of image display, zooming, and panning were excellent. The Visual Analyzer window is ergonomically efficient, since all the tools have buttons on the provided icon bar. In addition, the option of showing the layers schematic and a magnification/roaming window in the left sides of this viewer were helpful to have in the same window, reducing the amount of desktop windows open and the necessity of switching between open windows. Image header documentation was provided in virtually every dialog box at the file input section under an “info” button. Among other features, many functions support runtime reservation, a form of batch mode operation, in which the user can specify the time to run CPU- or memory-intensive operations. In addition, a progress bar is programmed in most dialog boxes to report progress when running a task. The bar is embedded in the window of operation, making it a useful gauge of progress since the parameters of operation are visible while running.

With its comprehensive assemblage of image processing tools, Earth 2.0 has few drawbacks to note. Among the few kinds of functionality to note as lacking are the limited raster GIS analytical functions and lack of a log file capability. Rescaling image data is not an obvious utility on the menu system, but this task can be accomplished by saving changes to color table transformations. Raster spatial analysis limitations can be overcome by installation of a comprehensive grid-based GIS package or module (Earth 2.0 readily imports and exports ArcView format grids). Image rescale functionality, such as changing ranges of data values by statistical or min/max parameters would be a useful addition to future versions for scientific and highly technical applications. Version 2.0 does include a tool for changing the data type (e.g., # bits per pixel, signed/un-signed), but not the range of data within these type constraints. Complex image analysis projects involving major data conversion and management operations could also be better managed with an additional tool to record operations, metadata, or tracking lineage. The metadata and lineage information can manually be added to derived data, but a log record would be useful for large production tasks. A convenient coordinate conversion tool (or calculator) is provided as a “Tools and Utilities” function. While this tool converts between many projections, coordinate systems, and datums, it only works with points, text, and DXF vector files.

Scientific and high-end image processing users have but a few tradeoffs to consider with the Earth 2.0 software. The package does not have a visual modeling capability for complex image and raster GIS analysis functions. Interestingly, the company also produces and sells Data Flow Modeling (DFM) technology, a software package with flight simulation, war game, diffusion modeling, and virtual reality applications. This Visual IDL Programming system, trademarked by Pixoneer’s parent company (Intersys Inc.) and marketed by Research Systems, Inc., would be a very valuable enhancement to the Earth 2.0 software, if a convergence or integration is not available soon. On the other hand, the inclusion of advanced orthorectification, a neural network classifier, and SAR/DEM tools bring the software into the high-end and scientific realm of analysis in this version of Earth. These modules are included in the Earth 2.0 software at no additional cost.

Product pricing for Earth 2.0 ranges from $4200 (floating server) to $3500 (locked single use) per license for commercial users. Military/government licenses range from $2500 to $3,000 (locked and floating, respectively.) Educational licenses are also offered with discounts. Multi-seat and site license prices are available with further discounts based on number of seats. In addition, the purchase of software comes with technical support.

Documentation and Tutorials
Earth 2.0 comes with online user help, tutorial, and access to a forthcoming series of educational modules. The tutorials walk the user through the general analytical tools of the software. The text is instructive in the protocols to accomplish the tasks, providing software-specific information progressively without jargon. There is little redundant information from chapter to chapter, so the completion of the tutorials is quite a progressive, comprehensive introduction to the software. Key dialog boxes and sidebar explanations are provided throughout. The sample data included with Earth 2.0 for this review included aerial orthoimagery, KOMPSAT, LANDSAT, and SPOT satellite data imagery and DEMs. The online help is a very straightforward reference to the software, including a well-organized contents that mirrors the menu and submenu system of the software. Knowledge of the underlying algorithms is highly advised since the help contents are very pragmatic outlines with little theoretical or underlying data assumptions provided. References to such detail and assumptions might be provided but are not included in the documentation. A few cautionary notes about implicit assumptions and data are noted in the tutorial and could be added to future versions of the online help. This information is also a prime candidate for the company’s ongoing education module development. Presumably, these forthcoming educational modules will greatly bridge this gap for the novice user. Pixoneer informed this reviewer of work in progress on an additional Reference Manual with technical descriptions and underlying theory/algorithms to be provided online with the available tutorial and help files.

Technical Support
Technical support is offered free for one year with purchase of a software license. This includes free upgrades of software, on-line and toll-free telephone support (9:00-5:00 EST), online FAQs, the PDF tutorials, and net-training via the Pixoneer website. Pixoneer offers separate, fee-based workshops for intensive training in Earth 2.0, including a Basic and Advanced course in Earth software as well as general introductory workshops on Geomatics, and Basics of Remote Sensing to suit user needs. During this review, technical support was promptly provided for general questions during the installation and review, both by telephone and e-mail.

Installation
An installation manual comes with the software, which is available on cd-rom or via Internet download. The software easily installs in any user-specified program filespace and requires moderate storage (~700MB installed complete with software, data, and tutorials.) License registration is handled by a single file or installable license manager for floating licenses. The single seat installed for this review was easily updated with a new license file after the 30-day demo period had expired. The software does not include an uninstall function, presumably relying upon the operating system to remove the program from the registry.

Recommendations
Pixoneer is offering a free 30-day demo of Earth 2.0 to users. Based on the functionality, short learning curve, and overall ease of use, Earth 2.0 will merit the attention of many remote sensing users, particularly those seeking a powerful, easy-to-use, and relatively affordable image processing and classification system to augment GIS applications. Ease of use and ergonomic design are commendable with this software. The icons have intuitive pictographs for their respective operations, but more important, the arrangement of buttons on the individual viewers and submenus makes it easy to navigate the software from step-to-step through image analysis. The help is accessible from the main menu but also is available in most analysis menus and dialog boxes in context-sensitive format.

Earth 2.0 can be downloaded from Pixoneer’s website for trial use. In addition, the company is developing educational modules that will be an attractive accompanying item for educators and professionals seeking to expand their use of remote sensing. Some of the high-end functionality of Earth 2.0 (orthorectification, SAR analysis, DEM generation, and neural network classification) will be welcome to users previously unable to afford or access these levels of processing typically requiring optional modules or other specialized software.



Reviewed by:
Thomas R. Allen
Dept. of Political Science and Geography
Old Dominion University
Norfolk, Virginia 23529-0088
Tallen@odu.edu


Contact information
Pixoneer Corporation
7777 Leesburg Pike, Suite 7LS
Falls Church, VA 22043 USA
703-852-2162
1-866-PIXONEER
703-852-2170 (fax)
www.pixoneer.com
info@pixoneer.com