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Lidar Interoperability: The Need for Common Guidelines and Practices

Lidar Interoperability: The Need for Common Guidelines and Practices. ASPRS Annual Conference Thursday April 29, 2010 San Diego, CA. Karl Heidemann, GISP Physical Scientist U.S. Geological Survey, EROS. Lidar Vocabulary.

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Lidar Interoperability: The Need for Common Guidelines and Practices

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  1. Lidar Interoperability:The Need for Common Guidelines and Practices ASPRS Annual Conference Thursday April 29, 2010 San Diego, CA Karl Heidemann, GISP Physical Scientist U.S. Geological Survey, EROS

  2. Lidar Vocabulary • Lidar: Point data representing the X-Y-Z location, with other attributes, of any terrestrial target reflecting the laser pulse. • Not limited to bare-earth points • Not a surface such as raster DEM or TIN • DEM: Digital Elevation Model of the bare-earth surface, almost always raster. • DEMs derived from Lidar are still just DEMs.

  3. All-Return Lidar (Points)

  4. Bare-Earth DEM (Surface)

  5. A Little Background • Lidar became commercially viable in the mid-late 1990s • Initially regarded solely as a means to develop bare-earth DEMs - little interest in the point cloud data • Lidar technology was developed by a number of mapping firms working in a competitive, commercial environment • Data producers developed their own methods, practices, software, and deliverables – largely driven solely towards a DEM deliverable • The competitive environment allowed for much innovation and rapid development of the technology, however… • … it also contributed to the significant variations in how point data is handled and delivered today

  6. Lidar Specifications • Appropriately dictated by topography, landcover, and primary use of the data • Post Spacing/Point Density • Spatial Accuracy (Vertical & Horizontal) • Classifications • Others… • Cannot realistically be uniform across the nation • Mohave Desert • Great Smokey Mountains • Gulf Coast • Accepted that specifications will vary within a national collection effort

  7. Practices • Currently unique to project, data producer, software, and instrument • Some variations are inevitable, acceptable, and healthy for continued innovation in the industry • Others pose significant impediments to a “seamless” National Lidar effort: • Point delivery - completeness • Classification – completeness • Accuracy – assessment and reporting • Metadata – consistency and completeness • Calibration & Boresighting – consistency • Adjacent Project Registration

  8. A Possible National Lidar System Delivery Cache Common Data/Product Cache User Interface Software XML Metadata & Reduced Resolution Views User Request for Data, Analysis, & Derived Products Data Delivery Management Software Systems Check for Existing Data/Product Data Analysis and Processing Software Systems Finished Products Data Access and Control Software Systems Points Needed to Fulfill User Request LAS Data Stores (petabytes) Metadata and Index Stores

  9. USGS-NGP Lidar Guidelinesand Base Specification • Prompted by ARRA funding for lidar to support the NED • Clarify USGS-NGP minimum requirements for NED usage • Identify common buy-up options • Initially viewed as a one-pager • Wide variety of lidar issues caused expansion of scope • Improve consistency across lidar point deliveries • Allow waivers for flexibility (previous collections; science) • Addresses both point cloud data and derived products • Assures delivery of bare-earth DEMs suitable for use in the NED • Assures delivery of more consistent point cloud data for use in other scientific and mapping applications • Specs to remain durable beyond ARRA projects

  10. Status of the Base Specification • Still a draft, the Spec has already been tentatively embraced by numerous other organizations: • FEMA, NRCS, NGA • Dewberry, Merrick, URS • ASPRS, MAPPS • Although planned to be finalized and published this year, periodic updates are presumed • Expectation that a broader Federal Lidar Spec will be developed • Common body dealing with point clouds and practices • Appendices specific to individual agencies/projects • Collection specifics • Derived product requirements

  11. ASPRS Lidar Best Practices • Growing movement for national lidar is adding urgency to the need for industry “standards” and Best Practices • Significant topic of discussion at ASPRS Lidar Subcommittee Meeting of this conference • Important issue to other ASPRS Divisions • Upcoming ASPRS Airborne Lidar Manual includes sections on Best Practices • Endorsed Best Practices expected to be drawn from multiple sources: • ASPRS Airborne Lidar Manual • USGS-NGP Lidar Guidelines and Base Specification • Other inputs …

  12. Lidar Interoperability:The Need for Common Guidelines and Practices Discussion Karl Heidemann, GISP Physical Scientist U.S. Geological Survey, EROS

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