U.S. Department of the Interior U.S. Geological Survey 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 ☀ 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.

All-Return Lidar (Points)

Bare-Earth DEM (Surface)

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

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

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

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

USGS-NGP Lidar Guidelines and 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

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

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 …

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