Details
- Data are received in various formats, datums, and projections and are processed to a common format, datum, and projection for data storage and provisioning purposes. Errors are reviewed and, when possible, removed. Some data are further processed to generate bare-earth products, but the level of processing varies with each data set.
- Distribution system generates a variety of elevation products from the mass point data including contours, points (of varying return number and classification), intensity images, and full DEMs. These products can be requested for unique, user-defined areas, projections, datums, units, and formats.
- Data can be selected by a user-defined area of interest
- Data are available in multiple projections and datums, and the following output formats:
- ASCII X, Y, Z Pts.
- Floating Pt. Grid
- 8-bit Tiff
- 32-bit Float Tiff
- Shapefile Contour
- DXF Contour
- LAS 1.x
- LAZ
- ASCII Grid
Notes and Limitations:Coverage varies from location to location—some areas feature multiple years of data and other coastal areas feature no coverage. Users should not use this data for critical applications without a full awareness of the limitations. The data is provided nearly as received. The Center does review the data but makes no guarantees on reported vertical or horizontal accuracies.
Early data were flown at lower resolutions (0.25 pts/meter) and are typically not available with bare earth classification. More recent data can exceed 8 pts/meter and have bare earth surface classifications. Accuracies (95 percent confidence) range from 10 to 40 cm in open terrain; the specifics of each data set are provided via metadata and fact sheets.