University of Arkansas Libraries - Data Viewing Tutorial

This webpage is designed to assist the new user wishing to locally view geospatial data (especially that from GeoStor) retrieved from across the web or otherwise. It consists of a tutorial on the usage of GeoStor, a web-based gateway to a wealth of geospatial data covering the State of Arkansas, and ArcExplorer, a freely available software that affords basic mapping and spatial querrying of geospatial data.

Before beginning it is important to have an understanding about geospatial data. There are many excellent descriptions, including the one used by the US Geological Survey:

Information that identifies the geographic location and characteristics of natural or constructed features and boundaries on the earth. This information may be derived from, among other things, remote sensing, mapping, and surveying technologies.

This webpage consists of two sections, the first being the tutoral on GeoStor, and the second being the tutorial on ArcExplorer.

An on-line data delivery system that allows the user seamless access to digital map data (GeoData) of any area in Arkansas with no subscription fee.

Browser requirement - There isn't one. For purposes of illustration this tutorial uses Mozilla Firefox.

The Java requirement - You've got Java installed on your machine right? Okay, likely you're not sure. No problem. GeoStor requires that you have a specific version of Java loaded on your machine. If you don't already have the proper version on your machine don't worry, the GeoStor application will recognize this and send you to the Sun Java site to download the required version. It's free. You will only need to do this ONCE! If you require instructions on how to install Java the GeoStor webpage has an easy to follow replication of instructions reproduced from the Sun Java Site otherwise simply follow the on-screen prompts when you download.

The compression software requirement - Data presented for extraction on GeoStor resides on a single server. When the download request has been processed an emailed link will be provided to a ZIP-compressed archive file on a server. You'll need an archiving software capable of reading the ZIP format and unbundling (uncompressing) the archive file (.zip). If you're computer is running Windows XP you don't need to concern yourself with installing "zip" software. There's a compression software built into Windows Explorer. If you're not running Windows XP and you don't have an archiving software installed then you might wish to consider PKWare, UltimateZIP, PowerARCHIVER, or WinZip utilities. If you'd like a some help using zip files you might do a search on Google or some other search engine otherwise try this page if you're a Windows XP user. Once you receive the email and click on the link download time may take from 5-30 seconds depending on the volume of data requested and server loads.

Alright then. You've got the required version of Java loaded, you've got an archiving software capable of unbundling a "ZIP" file, and you're ready to start snooping around GeoStor for some data. The first thing you want to do is click on the Begin GeoSurf button. GeoSurf is a database query application that you'll use to browse and select data layers stored in GeoStor.

First things first. You'll need to login. If you've not registered in the past you'll need to do that before logging in. To register you may do so by clicking the Register button on the Login dialog box represented below. Once you've registered you'll use an email address that you've specified as your Login.

After you've logged in the data layer selection tool pops up. This is the interface you use to search the GeoStor database for data layers you are interested in. You are provided with a list of ALL the data layers present in the entire database - some of them are statewide in extent while others are much more limited in area. If would prefer to use the Spanish language version of GeoSurf simple go to Edit, select Preferences, select the Language tab, and then click the Spanish radio button. In any event, to begin Click on the Create Metadata Filter button to begin searching the database or simply peruse the Map Data Layers window by using the scrolling down through the list of layers.

The Metadata Filter tool pops up upon clicking on the Create Metadata Filter button illlustrated above. You have a variety of ways to narrow your search of the data layers. For the purposes of this tutorial a simple keyword search will suffice. Click on the Apply button.

After searching the database GeoSurf displays layers it has found that are immediately associated with the keyword. Clicking on any layer displayed in the list allows you to view the metadata in 'short form' or 'long form' in the righthand side of GeoSurf.

If you wish to obtain an entire layer of coverage (data for which may or may not extend across the entire), immediately after starting GeoSurf, or after applying only a metadata filter, you can simply click on the desired data layer and then on the Download Data Layer...button on the lower right. If you have not applied any geographic filter, that is you want an entire layer of coverage, you will receive the following information message:

If your intent is to acquire the entire layer of coverage just click No and proceed. Normally you will want to apply a geographic filter. Using a geographic filter to request only an area that you need speeds up processing time and minimizes your wait. So click Yes and go back to create the geographic filter, the introduction to which picks up immediately below.

At this point it's worth noting that applying a metadata filter before applying a geographic filter will reduce your wait time. It is best if you you can identify a certain layer or layers of interest using a metadata filter before using a geographic filter. Using a geographic filter without having used a metadata filter first results in the geographic filter being applied to ALL layers which would cause much uncessary processing time and you to have to wait.

If you are interested in finding out if there is data in a select area of the state, or if you wish to download a select area, you will need to click the Create Geographic Filter button. Upon clicking the button the Geographic Filter tool pops up. You can use the Geographic Filter tool to search/select and extract data for areas defined by:

When you perform a geographic filter in GeoStor the Oracle software uses what is called a fast, general "primary" filter. Any layers with data in the primary filter are returned. If you move to extract data, however, a second, more precise, extraction filter is used. In some cases, frequently in small areas, NO DATA may be found in the extraction. A small, special file will be prepared and delivered to the desktop informing the user of this situation.

Clicking on the Show Map button with either the Point Location tab or Bounding Box tab selected will bring up the Interactive Map Viewer - a tool that facilitates definition of the search/select area. You will be able to view the point or box you defined and (or) you can interactively define a point or box.

You can type in four Latitude/Longitude values using decimal degrees. The values should be NAD83 (North American Datum of 1983) based. If you don't know the values clicking on the Show Map button will allow you to interactively draw the bounding box on a map automatically defining the area.

The various data sets that were originally based on preexisting boundaries, such as the DLG data from USGS based on 7.5 minute quadrangle maps, have been merged into statewide, seamless data sets in GeoStor. However, if you already have data organized by these areas you can use (for example) the predefined USGS Quadrangle polygons to obtain data that will be compatible with your existing data. The data is interactively clipped from the seamless coverage.

IMPORTANT NOTES: Searching using a predefined polygon MUST be performed if you wish to extract data in that polygon. Predefined polygon based searching is slower than box or point searcher. Be sure to apply any applicable metadata filters FIRST to speed up the response.
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There are two sets of "controls" in the interactive map viewer. The Map Control and Filter. Map Control buttons allow you to zoom in and out, pan etc. but they do NOT change the location of the selected point or box. The filter buttons are the only tools that allow you to change the location of a point or the extent of a box.

These buttons are used to zoom in (plus) and out (minus). Remember that zooming the map does NOT change the point or box coordinates. The measurement shown in the map width box at the lower left of the map is NOT the search/extract (and extract) bounding box value. It is simply the extent of the current map window view. You can only change the search/select (and extract) extent with the slider bar on the text side of the window.

The button with the hand on it pans the map. Again, remember that panning does NOT alter the point or box values. It is also possible to pan (or zoom) and NOT have either the point or box within the current window!

Clicking on the button with the little outline of Arkansas on it to the right of Map Control: returns the map to the complete state.

Clicking button with the cross-hair on it at the top of the tool moves the selection to "point" mode - the Point Location tab will automatically move to the front of the text area when you select this button. A new point will be located on the map where ever you click the mouse. Note that the area to be searched/selected (and/or extracted) around the point is set using the slider bar on the Point Location tab.

Clicking the button with the little black box on it will shift the area selection to Bounding Box search/select (and extract) mode and the Bounding Box dialogue will shift to the top of the text area automatically. As you draw various boxes on the screen note that the coordinates in the bounding box dialogue are automatically updated.

IMPORTANT NOTE: Any actions in either the text boxes or on the map are not in effect until you click on the Apply button to the lower left of the window.

As you zoom in and out various reference map layers are displayed. Note that the map window layers are ONLY for geographic location reference - the data layers are NOT displayed in the map window.

One final note on the filters. You may wish to return to a same location in a future GeoStor access and to extract data from the same area or (if you have more than five (5) simultaneous jobs in the queue) you will be REQUIRED to either wait or return. You do not need to laboriously recreate a search criteria but can save them for future use as a stored filter. To save search and selection criteria – both the metadata AND the geographic component - you can use the Stored Filter tab accessible from the Edit drop-down Preferences button on the main GeoSurf menu.

To use the stored filter option you MUST first create a filter using the standard GeoStor metadata and geographic tools. Once you have the search and selection criteria set you need only click on the Save Filter button. Clicking on the Save Filter button and giving it a name will store the filter for future use. User named filters are accessible through the GeoSurf main menu Edit drop-down Preference tab. Once you have the preference tabs in view select the Stored Filter tab. You can now exit GeoStor and, when you return, you can quickly apply the same criteria.

When returning to GeoStor, if you want to use a stored filter you MUST select a named filter from the drop-down list in the Stored Filter tab.

Once you have determined the existence of a data layer of interest and decided upon a geographic filter you are ready to download the data. You might, however, wish to preview the data before you request a download. Users can preview actual vector data or the footprint outline of actual raster data before downloading data. Once you have created a geographic filter select the Preview Data Layer button on the GeoSurf main menu.

Users can set preview preferences such as: Display background layers, which allows the user to see the previewed layers on top of County Boundaries and Major Roads; Show feature information, which allows the user to click on a feature and expose the attributes of the feature (Identify Tool); and Reproject the preview data which will give the data a different shape in the preview window. Preview preferences are accessible through the Edit button on the GeoSurf main menu.

If your data layer is Vector (Look for "Vector Data" or "Point Data" in top portion of Metadata short form) in nature (Vector data may be either point, line, or polygon or a combination) you'll need to specify the following parameters:

If your data layer is Raster (Look for "Raster Data" in top portion of Metadata short form) in nature (Raster data is sometimes called "image data." Image data is stored as raster data set of binary or integer values where each raster/grid-cell/pixel, has a value) you'll need to specify the following parameters:

This first parameter you must specify has to do with whether the vector data is to be clipped to the boundary of the area you specify or if touching is used. In a Boundary clip any line or polygon that has all or part within the search area is clipped at the edge of the bounding box or polygon. Using Touched all the line or polygon of any element (feature/object) that is wholly or partly within the search area are delivered even if only a part of the line or polygon touches the search area.

You can select different coordinate systems by simply using the drop-down list and clicking on the desired system. The list of systems from which to choose is presented below.

NAD83 Universal Transverse Mercator, Zone 15 North, Meter
NAD27 Universal Transverse Mercator, Zone 15 North Meter
NAD83 Latitude/Longitude, Degree
NAD27 Latitude/Longitude, Degree
NAD83, Arkansas State Planes, Southern Zone, US Foot
NAD83, Arkansas State Planes, Southern Zone, Meter
NAD83, Arkansas State Planes, Northern Zone, US Foot
NAD83, Arkansas State Planes, Northern Zone, Meter
NAD27, Arkansas State Planes, Southern Zone, US Foot
NAD27, Arkansas State Planes, Northern Zone, US Foot

The Format drop-down menu provides you with several different data/vendor formats from which to choose. The GeoStor 3.0 options are:

GIF Image (a simple image format to quickly view vector data)
ESRI Shape
ESRI Coverage
ESRI Arc/Info Export (e00)
MapInfo MIF/MID
MapInfo TAB
AutoCAD DWG/DXD
Intergraph/Microstation Design DGN
Intergraph GeoMedia Access Warehouse MDB

Raster data is delivered in a range of possible formats. The Format drop-down menu provides you with several different data/vendor formats from which to choose. Because of the different properties of various raster data not all output formats are supported for all data types. The GeoStor 3.0 raster format options are:

GeoTIFF (TIF)
ArcInfo Band Interleaved Grid (BIL)
ArcInfo ASCII GRID (ASC)
ENVI Raster
ERDAS (IMG)
ERDAS (LAN)
PCI Raster (PIX)

Once you click Submit GeoStor begins processing your data download request. Generally vector data is processed very quickly while raster may be quite time consuming - sometimes as long as a full day or two. After clicking on the Submit button the following message will appear on your screen:

As soon as the data processing is completed on the GeoStor server your e-mail is automatically mailed a message. The body of the message contains a URL. If you click on that URL in most mail systems the download of the data will begin. For older, text-based mail systems the user will need to note the URL and enter it later in a browser. Each job is provided with a unique job –id. If you have problems or questions please note the ID number (not pictured) at the bottom of the email.

Data will remain on the server for 72 hours after completion and then it will be automatically removed. The data will remain after a download so you may return and download again – if the 72 hours have not expired.

The data file(s) are compressed in a single archive file with a zip file extension! No problem! Simply click on your archival software's Extract button. You'll then be prompted for the location at which to save the extracted files. It is suggested that you find a "Temp" folder in which to put the file.

You will need to use one of the various unzipping software packages that are available and place the extracted files in the proper place on your local machine. Each of the zip files will have an FGDC compliant metadata file for the selected data in a html format. It will also contain a number of other files and the contents of the zip files will vary depending on the vendor format selected. For ESRI shape files, for example, the zip file will contain four files that have the extensions .csf, .dbf, .prj, .shp and .shx.

This concludes the Getting Started with GeoStor tutorial. The next section consists of a brief tutorial on the use of ArcExplorer as a data viewer.

Section 2

Getting Started with ArcExplorer

A Tutorial on Using ArcExplorer

as a Data Viewer

(http://www.esri.com/software/arcexplorer/index.html)

What is ArcExplorer?

ArcExplorer is a lightweight GIS data viewer developed by ESRI. This freely available software offers an easy way to perform basic GIS functions. ArcExplorer is used for a variety of display, query, and data retrieval applications and supports a wide variety of standard data sources.

ESRI offers both Windows and Java versions of ArcExplorer. ArcExplorer 2 is the Windows version of ArcExplorer. ArcExplorer 9 is the Java version, which offers cross-platform support for Windows, UNIX, and Linux. Both versions of ArcExplorer can be downloaded for free off the ESRI Web site. This tutorial concerns the Java version. ESRI offers on-line access to the ArcExplorer Users Guide should you wish to see it.

ArcExplorer title window.

ArcExplorer 9 supports the following data formats:

Other images are supported if they are in a MapService started by ArcIMS Administrator but for the purposes of this tutorial we'll be using Shapefiles and TIF images. At this point it should be mentioned that for those image formats that use "world files," the world files must accompany the image when used in ArcExplorer 9.

A Little About Data

This tutorial will feature the use of Shapefiles (an ESRI developed format), a format of the vector data type, and TIF, an image format of the raster data type.

Shapefiles are a data structure (format) for storing the location and descriptive attribute information of features on the Earth's surface. Features are mapped as points, lines and polygons but topological associations are not provided. A single Shapefile only stores one type of feature, either points, lines, or polygons.

All Shapefiles include a data table with fields that describe the individual features. For example, if the Shapefile stores information about manhole covers, each point in the Shapefile represents the geographic location of a manhole cover, and each record in the Shapefile's data table describes each of these manholes with fields like cover number, manhole depth, last inspection date, etc. A shapefile is denoted by its .shp extension.

Image data is a graphic representation or description of an object that is typically produced by an optical or electronic device. Some common examples of image data include remotely sensed data, such as satellite data, scanned data, and photographs. Image data is stored as raster data set of binary or integer values where each raster/grid-cell/pixel, has a value.

In the case of a remotely sensed satellite image, each pixel will have a value representing electromagnetic energy, perhaps that reflected back to the sensor from a portion of the Earth's surface. In the event the image is that of a scanned document, the value assigned to each pixel is a function of the brightness associated with a particular point on the document.

ArcExplorer 9 - Java Edition

Notes:

ArcExplorer 9 requires JRE (Java Release) 1.4.2. To find the version of JAVA installed on your machine, go to the Control Panel and then to Add/Remove programs. Your Java version is probably listed there. If you have used GeoStor on your machine previously you are likely to have JRE 1.4.0. If you have a recent version of Netscape installed, say v7.1, then you will have at least Java v1.3x installed.

As for University of Arkansas Mullins Library computers, almost all of them have Netscape v7.1 installed, and so they also have Java v1.3x installed as well. Millenium, the library's mangement software also uses Java v1.3x and that is installed on a majority of the staff computers, but it is not on any public access machines.

Regardless of whether or not you have, download this file. It has both the required JRE and the ArcExplorer setup program (note that you must run the JRE prior to launching ArcExplorer 9):

Installing ArcExplorer 9 for Windows
To begin installation, navigate to AE9Java.exe in the directory where you downloaded it from the Web.

After installation, click Start | Programs | ArcGIS | ArcExplorer 9 to open ArcExplorer 9.

For instructions on downloading versions of ArcExplorer for platforms other than Windows or UNIX please visit the ESRI website.

In order to follow along with this tutorial you will need to have the Chicken House layer downloaded from GeoSTOR as part of the preceding GeoSTOR tutorial.

Viewing data in ArcExplorer is EASY! After firing up ArcExplorer load up data for viewing by simply navigating to the data file using the red "+" on the main menu bar.

The Catalog dialog box will open. On the right-hand side use the File Type drop-down menu to select either Shapefiles or Image Files, then browse to the folder containing the file you wish to view.

Once you've reached the data file select it then click on the Add Layers icon in the upper left-hand corner.

After closing the dialog box the layer(s) you selected will appear in the margin on the left side. Click on the little empty box next to the layer title and ArcExplorer will display the data in an automatically randomly assigned set of display properties including style, color, and size.

Changing the display properties is a snap. Select the layer you wish to change and then do a right mouse click. On the menu that subsequently appears click on Layer Properties and change the settings as you please.

Once you've edited the display properties your preferences are displayed. It's that easy!

Now that you've learned how to display shapefiles you may wish go on to image files. For this next step let's assume you have download an image file covering approximately the same area as the two shapefiles displayed above. For purposes of this tutorial using GeoStor we have selected and downloaded 1999 Arkansas Land-use/Land-cover: Spring using the Washington County existing polygon geographic filter, and have specified NAD83 Universal Transverse Mercator, Zone 15 N, Meter as the Coordinate Sytem, and GeoTiff as the image format.

After unzipping the downloaded archive file containing the image file change the File Type to Image Files and browse to file then click on the Add Layers icon in the upper left-hand corner as you learned to do earlier.

If you already have layers loaded at the time you display the image file you may have covered them with the image file. Layers are displayed in the order in which they are loaded. Simply drag and drop the layers to change the order of display and therefore visibility. You may wish to change the Layer Properties (as you earlier learned to do) of the image file to make it translucent as was done to the file shown below.

This concludes the Getting Started with ArcExplorer and Data Viewing Tutorial.