README FILE FOR DIGITAL ORTHOPHOTO DATA SHARING DVD #3, version 1.1 This DVD was prepared by the Wisconsin Department of Natural Resources (DNR), Bureau of Technology Services. These notes were last updated on August 22, 2005. For information about the contents of this DVD, contact a DNR GIS Data Specialist by sending e-mail to geodata@dnr.state.wi.us. Comments or suggestions for improving the quality of DNR GIS data sharing products are appreciated. 1. LEGAL DISCLAIMER This DVD includes digital orthophoto (DOP) imagery from the Central GIS Data Repository of the Wisconsin Department of Natural Resources (DNR). The DNR makes no warranty as to the suitability of the information provided on this DVD for any particular application. Refer to the file 'dnrlegal.txt' located under the root directory on this DVD for a complete statement of Wisconsin DNR Legal Notices, Disclaimers and Terms of Use. The following is an excerpt: NEITHER THE STATE OF WISCONSIN, THE DEPARTMENT OF NATURAL RESOURCES NOR ANY OF ITS EMPLOYEES SHALL BE HELD LIABLE FOR ANY IMPROPER OR INCORRECT USE OF THE INFORMATION DESCRIBED AND/OR CONTAINED HEREIN AND ASSUMES NO RESPONSIBILITY FOR ANYONE'S USE OF THE INFORMATION. THE DEPARTMENT PROVIDES THIS INFORMATION ON AN 'AS IS' BASIS. ALL WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING...FITNESS FOR A PARTICULAR PURPOSE...ARE DISCLAIMED. Additional information about applicable legal issues can be accessed on the WiDNR Website Legal Information Page, at: www.dnr.state.wi.us/org/legal/WebSiteLegalInformation.htm 2. DATA FORMAT The DOP imagery on this DVD is provided in a series of county-level mosaics in compressed MrSID (Multi-Resolution Seamless Image Database) format. The data provided on this DVD are intended for use with GIS software that support MrSID format. 'MrSID' is a trademark of LizardTech (http://www.lizardtech.com/ ). The information provided on this DVD is in no way intended as an endorsement of LizardTech or its products. 3. GEOGRAPHIC REFERENCING SYSTEM The data on this DVD are referenced to the DNR's standard geo- referencing System, Wisconsin Transverse Mercator based on the 1991 adjustment to NAD83 (WTM83/91). The projection parameters for WTM83/91 are as follows: PROJECTION TRANSVERSE UNITS METERS 0.9996 (Scale factor at Central Meridian) -90 00 00 (Longitude of Central Meridian) 00 00 00 (Latitude of Origin) 520,000 (False Easting) -4,480,000 (False Northing) A WTM83/91 projection file ('wtm83-91.prj') intended for use with ArcGIS software is located under the root directory on this DVD. Additional information about WTM83/91 can be accessed on the DNR's internet website: http://dnr.wi.gov/maps/gis/wtm8391.html 4. DATA DOCUMENTATION (METADATA) Basic information about the characteristics of the digital orthophoto imagery on this DVD is provided in a 'metadata' file that accompanies each set of MrSID files. In most cases the content of these metadata files is based on information provided by the producer of the digital orthophotos. Information in these metadata files generally includes: Format, DOP Producer, DOP Custodian, Intended Display Scale, Ground Resolution, Projection, Horizontal Datum, Accuracy, File Size, Description of Source Imagery, Leaf On or Off, Spectra, Scale of Source Photography, Rectification Source, and Usage Restrictions. Each set of MrSID files is also accompanied by a text file that is produced by the MrSID compression process, stating the compression factor used in creating the MrSID files. 5. BLACK 'COLLARS' SURROUNDING DOP IMAGES When displaying the MrSID-format DOPs, you may notice a black collar surrounding all or part of the image. This black collar is an artifact of the MrSID image compression process. Future releases of MrSID compression software are expected to address this issue. Some varieties of GIS software enable users to render the DOP collars transparent by using map symbolization tools. For example, when using ArcView version 3, this can be done by adding the .sid file to the ArcView view, double-clicking on it to open the 'Image Legend Editor', selecting 'Colormap...', and making the values 0-5 transparent. Note that because the values of the image are being manipulated, the process of rendering MrSID DOP collars transparent may also result in other dark areas within your image (e.g. waterbodies) becoming transparent as well. 6. 'COMPOSITE' MrSID MOSAICS AND DOP SERIES SHAPEFILES For some Wisconsin counties, the most current DOP imagery available to the DNR is derived from aerial photography flown in two or more years. In such cases the DNR selects the most current available imagery for each portion of the county and mosaics the DOPs together into a county- wide MrSID-format image. We use the term 'composite' for MrSID images derived from DOPs with multiple source years. To help identify the source year of imagery for a portion of a county DOP composite image, a polygon 'DOP series' shapefile is created containing aerial photo source year information. The DOP series shapefile accompanies the corresponding MrSID file (under a '\shape' folder). The source year information is an attribute of the shapefile which can be queried using ArcView, ArcGIS, or other software that supports shapefile format. The attribute information in the DOP series shapefile is derived from documentation provided by the producer of the original imagery. 7. SUMMARY OF CONTENTS ON DVD #3, version 1.1 This DVD includes digital orthophoto coverage in MrSID format for the following Wisconsin counties: County Year(s) of File Size (MB) Source Imagery ====== =========== ============= Ashland 1992, 1998, 1999 269 Columbia 1992, 1997, 1998, 2000 98 Crawford 1992, 1993, 1994, 1995, 110 1998, 1999, 2000 Dane 2000 163 Douglas 1996, 1997, 1998 232 Grant 1995 181 Green 1995, 1998, 1999, 82 2000, 2001 Iowa 1995 106 Iron 1992, 1998, 1999, 2000 182 Juneau 1992, 1998, 1999 125 Kenosha 2000 414 Lafayette 1995 98 Lincoln 2001 134 Marathon 1992, 1998, 1999, 2000 224 Milwaukee 2000 364 Ozaukee 2000 369 Price 1986, 1992, 1998, 1999 184 Rusk 1992, 1998, 1999 176 Sawyer 1992, 1998, 1999, 2000, 181 2001 Shawano 1992, 1998, 1999 172 Vernon 1995 111 Washburn 1992, 1998 139 Waupaca 1992, 1998, 1999 128