THEME: Elevation (1:250,000 scale)

1. Data set name: elev_grd

2. Originator: Interrain Pacific

3. Date: 2/96

4. Edition: n/a

5. Description: This dataset is a representation of elevation based on 1:250,000 scale digital elevation model (DEM) data obtained from the USGS EROS Alaska Field Office. The data originally organized by 1:250,000 scale USGS quadrangles were merged to cover the entire Glacier Bay ecosystem.

6. Data Set Status:

7. Geographic Coverage Description: This full resolution elevation data layer covers the northern panhandle from Yakutat to South Baranof Island and Skagway to Hobart Bay.

Please check appropriate USGS 1:250,000 maps:

12. Theme keywords:

13. Access Restrictions: Data transfer costs will be based on staff time and media costs.

14. Use Restrictions: Data may not be sold.

15. Processing Information:

16. Raster File Form

17. Raster File Sensor:

18. Sensor Resolution______meters

19. Imagery Information

20. Vector File Format:

21. Spatial Data Media Type (for data with a spatial component not stored in a graphic, mapping or GIS software): n/a

II. DATA QUALITY INFORMATION

1. Attribute Accuracy Explanation: Interrain Pacific has not conducted any formal accuracy assessments on this data layer or the source datasets.

2. Attribute Accuracy: __________% __X__Unknown

3. Description of Data Completeness: The primary constraints with 1:250,000 scale DEM datasets are those associated with the original data sources. That is, elevation information on 200 foot contours at 1:250,000 scale can never be better than the original source data. For example, coastal areas appear to have more problems in matching the coastline to the zero elevation contour. If used at scales where this mismatching is evident, the elevation data should be reprocessed using water bodies to mask these discrepancies.

Additionally, because the DEMs were created on a quad-by-quad basis, there are some edge matching problems (e.g. contour discontinuities, data gaps). As the quad-based datasets are merged, some of these discrepancies become obvious. Some problems can be removed by filtering or drawing information from neighboring cells. Care should be taken to maintain the overall integrity of the data during processing to correct problems at the quad margins.

4. Minimum Mapping Unit: ______ Unknown___ n/a___

5. Positional Accuracy Comments: The data presently meet USGS map standards.

6. Source Information:

USGS EROS Alaska Field Office; 4230 University Drive, Anchorage, Alaska 99508;
907-786-7020 (Contact person: Mark Shasby)

"Digital Elevation Models: Data User's Guide." 1990. USGS National Mapping Program Technical Instructions, Data Users Guide 5. Published by USGS, Reston, VA.

7. Date of Source Data:

8. Scale of Source Data: Originally developed at a resolution of 3 arc seconds (which translates to approximately 90m)

9. Data Processing Description: The USGS EROS Alaska Field Office processed Standard Defense Mapping Agency (DMA) DEMs into LAS images. Interrain Pacific then converted these files to an ARC/INFO GRID format and projected to UTM zone 8. Areas with zero elevation that were identified as water based on the Tongass National Forest Coastline (noaa_cst for areas within Glacier Bay National Park) were converted to NO DATA. Subsequently, Interrain Pacific used the elevation layer to develop slope, aspect, and shaded relief representations, as well as contours clipped to the Juneau, Sitka, Hoonah and Yakutat Ranger Districts, Admiralty Island National Monument, and Glacier Bay National Park.

III. SPATIAL DATA ORGANIZATION INFORMATION

1. Data Structure:

2. Raster File Row:

3. Raster File Column:

4. Raster File Vertical:

5. Raster File Number of Bytes per Pixel:

6. Raster file origin_________

IV. SPATIAL REFERENCE INFORMATION

1. Map Projection Name

V. ENTITY AND ATTRIBUTE INFORMATION

1. Attribute Labels:

Description: VALUE : Elevation in meters

VI. DISTRIBUTION INFORMATION

1. Distributor: Interrain Pacific

2. Distribution Liability: Interrain Pacific makes no express or implied warranties with respect to the character, fitness, function, accuracy, or capabilities of the information presented or the appropriateness for any users purposes. In no event will Interrain Pacific be liable for any incidental, indirect, special, consequential or other damages suffered by the user of this information or other person.

3. Standard Order Process: Data will be provided on tape or CD-ROM based on written requests.

4. Hardware media type: 8mm tape, CD-ROM.

5. File Decompression Technique: None.

6. Decompressed Data Transfer Size:

VII. METADATA REFERENCE INFORMATION

1. Metadata Date: Feb. 17, 1996

2. Metadata Contact: Interrain Pacific

VIII. CONTACT INFORMATION