This FAQ is Copyright 1999 by the GeoPlan Center at the University of Florida. This document may be reproduced, so long as it is kept in its entirety and in its original format.

Credits:
This FAQ was written by Andrea Goethals in 1999. It was updated in 2003 by Crystal Goodison, Sam Palmer, and Ilir Bejleri. Many thanks to the FGDL users for contributing questions.

Section 1: What is the FGDL?

1.1 - What is the FGDL?

The Florida Geographic Data Library (FGDL) is a mechanism for distributing satellite imagery, aerial photographs and spatial (GIS) data throughout the state of Florida. The data is organized by county, or other regulatory boundaries, and is distributed on CD-ROMs. The FGDL is warehoused and maintained at the University of Florida's GeoPlan Center, a GIS Research and Teaching Facility. There are currently over 350 layers of GIS data in the FGDL, including FDOR Tax Data and several types of Remotely Sensed images, such as LandSat TM and Aerial Photography. New data layers will be continuously added to the FGDL as they become available.

1.2 - Why have the FGDL?

The main benefits of the FGDL are its contributions to the availability, clarity and uniformity of Florida's databases.

*AVAILABILITY: Data can be distributed at less cost and more efficiently between state agencies and to the public and private sectors. Data is available for download free of charge on our website.

*CLARITY: Data are organized for use by non-GIS persons so that individual users will no longer be required to understand the more technical aspects of GIS to be able to accomplish geographic information analyses.

*UNIFORMITY: Data are organized with a standard format, projection and documentation; many users will not have to do any additional data processing in order to begin analyses.

1.3 - How was the FGDL developed?

Various GeoPlan Center projects have included the development of databases that were subsequently added to the FGDL. These projects include the Cross Florida Greenway Project, The Statewide Greenways Planning Effort, The National Pollutant Discharge Elimination System (NPDES), the FDOT Environmental GIS Database Development Project, and the FDOT Efficient Transportation Decision Making Project..

The FGDL has been compiled from data and images collected from numerous state and federal governmental agencies, as well as some nonprofit organizations and private companies. The Florida Department of Transportation (FDOT) is the lead agency contributing to the development of FGDL. In the past, the Florida Department of Environmental Protection (FDEP) has also contributed a great deal to the FGDL.

We use the Albers projection because two of our main data contributors are FDEP and FDOT who both work in Albers, and because we distribute the data in one statewide projection. UTM and Stateplane projections have zones that make it impossible to "connect" the different pieces of the state. We consider the ArcView on-the-fly projection an ESRI software problem/limitation and have been in contact with them regarding something a little more robust. Also many of our clients need more precise measurements (usually area) which Albers offers. Geographic Latitude Longitude is not a projection but a coordinate system and does not adjust for correct area, shape, distance or other factors.

The Albers Conic Equal Area projection uses two standard parallels to reduce some of the distortion of a one standard parallel projection. Although neither shape nor linear scale are truly correct, the distortion of these properties is minimized in the region between the standard parallels. This projection is best suited for land masses extending in an east-to-west orientation rather than those lying north to south.

Most of this projection info can be gathered from the web. Look at the sites from USGS and NEMA (the defense mapping agency). The most commonly referenced author of projections and their formulae is John Snyder, who used to be with USGS.

See these sites:
Map Projection Overview, Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Texas at Austin
Coordinate Systems Overview, Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Texas at Austin
Geodetic Datum Overview, Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Texas at Austin

There is a coordinate calculator on the market from Blue Marble called the Geographic Calculator. There may also be some other ones out there. Albers is a common projection so most calculators should have it, and the ability to enter the user defined parmaters (parallels, false-eastings, etc). Most of these calculators are for Unix and NT alike. The NT ones usually come in a Visual Basic (VB) type of interface that one could probably call from another VB app. The Unix or Linux ones are either command line or a TCL or Java interface that can also be called from other apps.

3.3 - How can I get more information about a particular FGDL dataset?

Please contact the source of the dataset, which is identified in that dataset's metadata. Metadata is included with every FGDL Data layer.

3.4 - Is there a standard for GIS data?

There is no real standard in the GIS industry at the moment. Just like the rest of the computer and tech industry most of the formats for data transfer and storage are proprietary. There is a group called the OpenGIS Consortium (http://www.opengis.org/) that is looking at ways to standardize GIS data.

3.5 - Does the FDOR Tax data have a graphical element?

FDOR Tax data are tables only, there are no parcel lines, polygons, or points associated with this data. The files are dBase (.dbf) tables. However, TAXS are the tax records summarized by section, and it is possible to link this table to the sections of the Public Land Survey System. For more information, please see the metadata for PLSS.SHP.

Section 4: FGDL Custom Software

4.1 - What is FGDL Extenstion for ArcMap 9.x?

The FGDL Extension for ArcMap 9.x is a toolbar designed to help users integrate FGDL Version 3 or later data into ArcMap 9.x documents. This extension works with FGDL Version 3, Version 2003, Version 2004, and later. This extension does not work with FGDL Version 1, 2, or 3.

Click here for more information.

4.2 - How is the new FGDL ArcMap 9.x extension different from the FGDL Version 2003 extension?

The new extension does not provide Geoprocessing tools.

Section 5: Other GIS Software

5.1 - How can I get ESRI's free GIS Viewer, ArcExplorer?

ArcExplorer comes on the FGDL CD-ROMs. Additionally, you can download it for free from ESRI's site. Please go to:
http://www.esri.com/software/arcexplorer/index.html

5.2 - What other GIS software is out there?

We are keeping a list of GIS Software at http://www.geoplan.ufl.edu/software.html.

5.3 - Will FGDL Data work with MapInfo software?

Yes. MapInfo Professional v.5.5 comes with a Universal Translator that reads ESRI shapefiles.

Section 6: Using FGDL Data and Imagery

6.1 - Can I make maps with the FGDL data in varying sizes? If I want to save an image as 640x480 or 1024x768 can it be done?

Since the data are digital you can create a map of almost any size. The limiting factor is the original source scale (for vector data) or resolution (for raster data). You would not want to create a 1:2,000 scale map with 1:100,000 data. All of our datasets come with documentation that contain information (metadata) about the scale, attributes, contact information, etc.

6.2 - I would like to display the satellite images of more than one county in the same view in ArcView. Each image has a black background for areas outside the county boundary. Is there a way to eliminate this black area so that one continuous image is formed once the images are overlapped?

Yes there is, at least for the Tmtrue and Tmfals images. (To be able to do this with multiband images such as the MSS images, you would need the Image Analyst extension.) Follow these steps in ArcView:

1. Make sure the IMAGINE extension is turned on. (With the Project Window active, go to FILE - EXTENSIONS to bring up the Extensions dialog box. Scroll down the list of Available Extensions, and make sure there's a check next to IMAGINE Image Support. Click on OK)
2. With a View active, add the image(s) to the view. (In the lower left corner of the Add Theme dialog box, put the Data Source Type as an Image Data Source for the Tm images to show up in the Add Theme dialog box.)
3. Double-click on the name of the Tm image in the View's Table of Contents to bring up the Image Legend Editor.
4. When the Image Legend Editor dialog box appears, click on the button that says Colormap.
5. Double-click on the colored rectangle to the right of the 0 value to bring up the Color Palette.
6. Select the transparent color (it is the top-left box with an x through it)
7. Press the Apply button in the Image Colormap dialog box.
8. Repeat these steps for all the images that you want to do this to.

6.3 - What is the minimum software requirement to open, use, and overlay FGDL datasets?

FGDL Data is meant for use with GIS software. There is a free GIS viewer made by ESRI called ArcExplorer. For more information about GIS software, see our page listing GIS Software: http://www.geoplan.ufl.edu/software.html. Note that software is usually not the problem when it comes to using the large datasets that are a part of GIS. The real problem is hardware. A good rule of thumb is that you can never have too much RAM when dealing with large GIS datasets. Also a good graphics card, 8MB or better, and a good size monitor 19" or larger.

6.4 - How do I view the FDOR TAX data?

All of the tax data is in .dbf format which can be read by ArcView, Quatro Pro, Excel, Access, etc. If you are in Arcview you can add a dbf file in the tables section of the project window. These data are stand-alone datasets. This is due to their size and lack of spatial reference. We are now working to accumulate parcel data so as to tie-in the tax tables to a spatially referenced parcel dataset.

6.5 - Using ArcView 3.1 for Unix, I have found that MrSID images don't read associated world files when read from CD. How can I fix this problem?

This problem can be fixed by copying images and world files to hard drive (local or networked) and then loaded into ArcView 3.1 for Unix. Another alternative is to upgrade to Arcview 3.2 and you will not experience this problem.

6.6 - Why do I get a projection error message in ArcMap when I am trying to view both FGDL Version 2003 data and FGDL Version 3 data?

This will happen because the prj file for FGDL Verion 3 makes ArcMap think that the data's projection is using the North American Datum of 1983 when it is actually using the HARN datum. FGDL Version 3 and Version 2003 data are in the same projection, but their projection files are different because the Version 3 prj file had to be edited and updated to be read correctly in ArcGIS 8.x. The best thing to do is delete the FGDL Version 3 prj file and replace it with the new prj file for Version 2003.

6.7 - What happened to the SHPO datasets ARCHIS & ARCSIT that were present in FGDL Version 3 but not in FGDL Version 2003 or Version 2004?

Many SHPO datasets were added for the FGDL Version 2003. ARCHIS was updated with new data and renamed to SHPO_STRUCTURES. ARCSIT was deleted from FGDL. This was done May 2003, so this will only pertain to CDs ordered after this date.

Section 7: Contacting the FGDL Team

7.1 - How do I contact someone concerning FGDL Data/Applications/Imagery etc.?

Please see our FGDL Feedback page: FGDL Feedback