ArcView Spatial Analyst Frequently Asked Questions

This FAQ covers most of the questions that come up with the installation and use of ArcView. If you cannot find the answer you are looking for here, visit the online discussion forum.

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General Questions

What is the difference between ArcView Spatial Analyst extension and the ArcInfo GRID module?

From within the ArcView environment, ArcView Spatial Analyst provides an intuitive, graphical user interface to most of the functionality implemented in ArcInfo GRID. The extension offers an ease-of-use advantage in the display and interactive exploration of GRID data. The commands are accessible from menu choices and interactive dialog boxes to expedite and facilitate the processing and analysis of raster data. The extension tightly integrates raster and vector data for spatial analysis in ArcView. The extension is customizable with the familiar Avenue scripting language and includes a C API for reading and writing GRID data sets. ArcView Spatial Analyst does not provide groundwater modeling tools, nor does the extension support grid stacks. ArcView Spatial Analyst does not allow the user to directly edit grid data; although, through the use of the Map Calculator, the Reclassify command, or Avenue scripting, one can create new raster data sets based on the values of one or more existing grids. ArcView Spatial Analyst does not support raster data projection; however, the extension includes a Warp tool for georeferencing grid data sets.

How does ArcView Spatial Analyst extension relate to ArcView 3D Analyst?

ArcView Spatial Analyst and 3D Analyst are two ArcView extensions with functionality that overlaps in the area of GRID data support and surface analysis. ArcView 3D Analyst provides exclusive tools for ESRI triangulated irregular network (TIN) creation, display, and editing; 3D shapefile generation; and 3D visualization and animation. ArcView Spatial Analyst provides exclusive tools for hydrological analysis, map algebra, and raster data processing such as grid statistics, geometric transformation, morphological functions, distance analysis, proximity mapping, grid reclassification, and density mapping.

Can I use ArcView Spatial Analyst with other ArcView extensions?

Yes. ArcView Spatial Analyst integrates seamlessly with other ArcView extensions. Complex spatial analysis and visualization can be performed with a combination of ArcView Image Analysis, 3D Analyst, Tracking Analyst, Network Analyst, Business Analyst, and other extensions.

What is a digital elevation model (DEM)?

A digital elevation model is a representation of the earth's surface for a geographic area stored in a digital file containing regularly spaced point locations with an elevation attribute. The United States Geological Survey (USGS) DEM is a specific data product that adheres to standards defined by the National Spatial Data Infrastructure. USGS DEMs can be downloaded for use in the ArcView Spatial Analyst.

Can I use the Spatial Data Transfer Standard (SDTS) formatted DEMs in ArcView?

Currently, ArcView Spatial Analyst does not directly support the SDTS formatted DEMs. There are utilities available to convert the SDTS formatted DEM to the standard USGS DEM, a generic ASCII raster file, or an x,y,z point file. After converting the SDTS DEM, you can import either the standard USGS DEM or generic ASCII file into ArcView Spatial Analyst to create a GRID data source.

 

Are there any sample scripts or extensions available for ArcView Spatial Analyst?

Yes. ArcView Spatial Analyst includes several scripts and extensions that are installed in the Samples subdirectory under the ArcView installation directory. The extensions include Cell Tools (grid cell properties), Hydrologic Modeling (hydrological analysis), Visibility Tools (visibility analysis), and Warp Environment (grid georeferencing). You can find more information about the use of these tools by opening the ArcView online help and clicking Extensions from the Contents tab. Then open the Spatial Analyst book and click Sample scripts and extensions. In addition to the scripts and extensions included with the software, there are a number of sample scripts and extensions on the ArcScripts Web page that have been developed by ESRI and members of the ArcView user community for use with ArcView. You can search for scripts and extensions specific to ArcView Spatial Analyst by clicking the ArcView Spatial Analyst category or entering "Spatial" as a keyword for the search engine. There are three extensions developed by ESRI to provide a graphical interface to ArcView Spatial Analyst functionality not found in the standard interface—Cost Distance Grid Tools (weighted distance analysis), Grid Generalization Tools (morphological functions), and Grid Transformation Tools (tools for geometrically transforming grid data). Each of these extensions includes the source project and scripts so that you can study the development of the extension.

What types of interpolation methods are available in ArcView Spatial Analyst?

ArcView Spatial Analyst includes the following methods for interpolating surfaces from point data: Inverse Distance Weighted, Spline (regularized and tension), Trend (polynomial regression), and Ordinary and Universal Kriging.

Where can I get more information about raster data and spatial analysis?

ESRI offers a classroom-based training course, Working with ArcView Spatial Analyst, that teaches basic raster concepts and introduces GIS modeling. ESRI also offers Web-based courses through the Virtual Campus. The Introduction to ArcView Spatial Analyst course is a collection of modules that present the basic concepts and functionality of ArcView Spatial Analyst. You can find appropriate books in the GIS Bookstore and others such as Raster Imagery in Geographic Information Systems [Amazon.com]. The ESRI GIS Jump Station is a great place to begin searching the Internet for a wealth of information about GIS, raster data, and spatial analysis.

Where can I get more information about the technical issues of ArcView Spatial Analyst?

ESRI offers technical support for ArcView Spatial Analyst by means of phone, fax, or e-mail. ESRI also provides self-help resources such as technical notes, discussion forums, and e-mail discussion lists. ESRI offers and monitors the ArcView-L discussion list, which focuses on issues specific to ArcView and frequently contains postings regarding ArcView Spatial Analyst and other extensions.

Data Questions

What data formats does ArcView Spatial Analyst support?

ArcView Spatial Analyst natively supports the ArcInfo GRID raster format and ArcView feature themes including ArcInfo coverages. This also includes data that can be loaded as a feature theme into ArcView such as CAD or Vector Product Format files as well as event themes created from tabular data. ArcView Spatial Analyst can convert USGS DEM, NIMA DTED, generic ASCII and binary raster formats, event themes, and all feature themes to the GRID format. Additionally, ArcView Spatial Analyst can convert supported image formats in ArcView to the GRID format for spatial analysis.

Where can I get data for use in ArcView Spatial Analyst?

There are several sample data sets that are included with ArcView Spatial Analyst software. Data sets for use with the Quick Start tutorial are installed to the AVTUTOR folder and include several grids, as well as shapefiles and a text file. In addition to the tutorial data, there are several large grids representing elevation and other data for Africa, Eurasia, and North America that are included on the CD—ROM. The Windows version allows you to access these grid files directly from the CD. You can also use the Source Manager to copy these grids from the CD to a workspace on your computer's hard disk. The UNIX version CD contains these same files; however, they are compressed and can be installed by an additional installation step (outlined in the Spatial.html document). Data can also be downloaded from the Internet, purchased from data vendors, or derived from field research. See the ESRI Data node for links to additional data sources.

Customization Questions

How do I manage ArcView Spatial Analyst data?

ArcView Spatial Analyst provides a data Source Manager for copying, renaming, and deleting GRID data sets. This dialog box, accessed by the Manage Data Sources choice on the File menu when view document is active, facilitates grid data management and properly accounts for the various files that constitute a GRID data source. The file manager of the operating system (Explorer in Windows) should not be used to manage GRID data. Using the operating system's file manager to manage GRID data sets can result in corrupted workspaces.

Can I customize ArcView Spatial Analyst?

Yes. You can develop custom applications, as well as access additional functionality not found in the standard interface, through the Avenue scripting language. ArcView Spatial Analyst also includes a C API for reading and writing GRID data sets.

Suport Questions

Why can't I see the sample extensions in the Extensions dialog box?

The list of available extensions in the Extensions dialog box (File | Extensions) includes all of the extension files (*.avx) in the directory (or directories) identified by two variables, $AVEXT (set and defined when installing core ArcView) and $USEREXT (defaults to $HOME if not defined by the user). The sample extensions are installed in the $AVHOME/Samples/Ext directory. You can copy the .avx file(s) from this location to one of the extension directories defined by $AVEXT or $USEREXT. For more information, see the document, "How to use the samples," in the ArcView online help.