Questions About PASDA, Using PASDA, and GIS Data
Maurie Caitlin Kelly
117 Land & Water Research Building
Penn State Institutes for the Environment
Penn State University
University Park, PA
The data on PASDA are available in several formats.
All data downloaded from PASDA--whether you use the Data Wizard customization interface or go directly to the ftp site--will be downloaded as a zip compressed file.
The original format of data available through PASDA varies. Much of the data is in ESRI shapefile (.shp extension) format. Older data--pre 2000--is in e00 exchange file format.
Imagery or raster data comes in several formats as well.You will either find tagged image file format (.tif extension), Mr. Sid (.sid extension) files, or Jpeg 2000 for ortho photos or digital raster graphics (digital topo maps from USGS). Digital Elevation Models (DEMs) are in DEM format.
PASDA does not provide offline data reproduction services, either on digital media or paper. All data available on the PASDA website can be obtained on digital media on a cost recovery basis.There are several organizations providing this service:
Delaware Valley Regional Planning Commission for aerial photography of Bucks, Chester, Delaware, Montgomery and Philadelphia counties in Pennsylvania and Burlington, Camden, Gloucester and Mercer counties in New Jersey. DVRPC also provides hardcopy prints in two sizes (Wall or Report) at various scales. Historical photos from 1995 or earlier are available at approximately 1"=400' scale (Wall size only).
Some local governments and counties provide reproduction services for their data. Please contact the individual counties for more information on pricing and availability.
Yes. There are some free viewers.These include:
ArcGIS Explorer is a free downloadable application that offers an easy way to access online GIS content and capabilities.
ArcExplorer is a lightweight GIS data viewer written in Java that is used to perform basic GIS functions (e.g., view, navigate, and query). It is a downloadable application that operates in a stand-alone environment and does not need to connect to a server.
ArcVoyager Special Edition allows you to add data, print maps, and query themes.
ArcExplorer Web. This program assists users in accessing Internet Map Services.
Mr. Sid files can be viewed using this free viewer.
DEM Reader is a Macintosh program for imaging USGS digital elevation models. The current version will create an elevation or relief map in grayscale or color from a DEM file. It comes in both PPC and 68K versions. "DEMster" is a Mac program that will create a grayscale Tiff file from a SDTS DEM file. This is an early beta version. "DEM30toTiff" will convert GOTOPO30 DEMs to grayscale tiff files. This is a no frills utility.
Map services are preconfigured GIS data served over the Internet. PASDA has numerous map services. These can be viewed or can be imported into your desktop GIS for use with your local data. For more information, check out our How to Connect to a Map Service tutorial.
It is easy to customize your data through PASDA.You can select the extent of your data (county, watershed, municipality), the projection, and you can even select several data sets at a time and place them in your data cart for customizing. Use the PASDA Data Wizard for all your customizations.
Most likely, if you have downloaded the data from the PASDA ftp site and you are having overlay problems, the issue is that your data is in a different projection or datum. There are several options. You may wish to try the PASDA Data Wizard which will allow you to select the projection of the data you download.
There are several things you may be encountering. First, be sure that you know from which DRG collection you downloaded the data. There are several different collections of DRGs, they have different projections and in some cases different datums. In addition, we have cropped one collection of DRGs (removed the collar information) so they are easier to use and mosaic with other data. You may see black sections on your DRGs where the collar information was removed. You will need to select the black area in your software and convert the color to transparent.
All of the data and services provided by PASDA are free and open to the public; nothing requires a password. If your computer is on a network that includes a Proxy Server, you may be prompted for a password due to your network settings. You should check with your network administrator to confirm whether you have a proxy or not. If you do have a Proxy Server the easiest way to resolve this issue is to add your Proxy Server information to ArcCatalog. In ArcCatalog select Tools - Options - Proxy Server and enter the information supplied by your network administrator. Once that is done you should not be prompted for a password when connecting to PASDA services. If you are using ArcGIS 9.2, you can provide the Proxy Server information in ArcCatalog by selecting Tools - Options - Connections. You may also need to make changes to your Internet Settings in the Windows Control Panel. Consult with your network administrator to help with your particular configuration.