Researchers will discuss development, assessment, and applications of the 3DEP and 3DHP programs.
2:00 – 2:15 PM – Preparing for the 3DEP baseline completion and transitions toward next-gen 3DEP and 3DNTM
With 3DEP nearing 100% baseline completion, the next generation of 3DEP is beginning to take shape. Based on the 3D Nation Study results and input from a broad range of stakeholders, the USGS has finalized a new design for 3DEP that provides increased lidar quality levels and refresh rates. The new program is designed with more flexibility to meet changing user needs and take advantage of improvements in mapping technologies. Â The program will include expanding the level of interagency coordination for topobathymetric lidar acquisition for inland rivers. The next generation of 3DEP will also emphasize research, including advancing program design, products, and services and engaging and leveraging the evolving 3D industry. The 3D National Topography Model is a new initiative to integrate elevation and hydrography data that includes the next generation of hydrography data from the 3D Hydrography Program (3DHP), and the next generation of elevation data from the 3D Elevation Program (3DEP). Research goals also include becoming more flexible in meeting user needs, and to move from a product production focus to a concept of a 3D Nation Ecosystem with a variety of inputs, products, and services. This presentation will cover the latest updates in the development of next generation 3DEP, 3DHP and the 3D National Topography Model.
Jason Stoker, USGS
2:15 – 2:30 PM – Research and Results of Creating a National Seamless 1-m DEM for Elevation-Derived Hydrography Geo Week 2025
The National Geospatial Technical Operations Center and the Earth Resources Observation and Science Center of the U.S. Geological Survey have researched and created a new National Seamless 1-m Digital Elevation Model (DEM) to support the 3D Hydrography Program. This is the first joint project by these two centers as part of the new National Geospatial Directorate. A seamless 1-m DEM requires merging multiple lidar projects with unique lineages to include the lidar sensor, bare-earth DEM generation methodology, source resolution, datums/projection, unit of measure, and geoid (mean sea level model). Our goal is to create a seamless 1-m DEM for the conterminous United States. Due to the size of watersheds, and the fact they do not respect political or UTM boundaries, we chose the North American Datum of 1983 USA Contiguous Albers Equal Area Conic projection for this dataset. We also converted the vertical datum, North American Vertical Datum of 1988, to the current GEOID18 model. We will review our workflow on data selection and staging, transformation, processing, spatial metadata creation, and publication. We will also discuss our methodologies for void detection, small and large void backfilling, and blending methods. Specifically, we will cover blending between lidar-to-lidar projects, and lidar-to-coarser datasets such as the 1/9 and 1/3 arc-second DEMs in areas where we did not have 3D Elevation Program lidar or had restricted areas such as military bases or tribal lands. Finally, we are going to discuss our novel approach of using difference rasters between projects to detect geometric offsets and temporal changes so that seamlines can be placed optimally. This presentation will show the results of our work generating three Hydrologic Unit 8 watersheds for the Upper Androscoggin River, Lower Androscoggin River, and Presumpscot areas.
Barry Miller, U.S. Geological Survey
2:30 – 2:45 PM – Large-Scale 3DEP Lidar Validation Using Open-Source Tools, Cloud Infrastructure, and Multi-Source Geospatial Data: A Case Study in Eastern Iowa and Puerto Rico
This study presents a comprehensive methodology for assessing the geometric accuracy of high-resolution topographic lidar data acquired as part of the U.S. Geological Survey’s 3D Elevation Program (3DEP). The methodology, implemented using open-source tools and cloud infrastructure with 3DEP data in Entwine Point Tile (EPT) format, encompasses various quality parameters, including interswath accuracy, same surface precision, point density, absolute accuracy (both three-dimensional and vertical), and consistency with adjacent 3DEP datasets. The assessment involves field surveys using Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS), total station, and ground-based lidar, followed by rigorous data processing and analysis techniques using multiple data types such as the National Land Cover Database (NLCD). The methodology is applied to a case study evaluating large-scale lidar data collected in Iowa in 2019, with interswath, inter-project, and same surface precision measurement locations chosen based on the NLCD’s impervious layer categories. Point density is calculated based on the latest recommendations from the American Society for Photogrammetry and Remote Sensing (ASPRS) Lidar Division. The study also includes comparison of 3DEP lidar data collected over the Puerto Rico at two different epochs. The results of the Iowa case study reveal that the lidar data meet or exceed the quality level 2 specifications, highlighting the robustness of the methodology and the value of the data for scientific, engineering, and policy-related purposes. This study serves as a showcase for conducting similar analyses at a regional scale, demonstrating the effectiveness of the methodology in ensuring the quality and reliability of lidar data for diverse applications.
Aparajithan Sampath, KBR, Contractor to US Geological Survey
2:45 – 3:00 PM – Validating Geometric Quality of 3DEP Lidar Data in Complex Terrain
This study evaluates the horizontal and vertical accuracy of aerial lidar data in diverse landscapes, focusing on developing innovative checkpoint targets and assessing geometric consistency with existing lidar datasets. A key objective is to evaluate lidar’s capability to map ground features beneath dense vegetation canopies. High-resolution terrestrial lidar scan data, collected in both open areas and under canopy, were utilized as a primary reference for validating the accuracy of the aerial lidar data in both case studies. Additionally, ground checkpoints were established using total stations in GNSS-denied areas, such as under dense canopy cover. Two case studies were conducted: Colorado (Urban and Complex Terrain): This case study encompassed an urban landscape alongside a region characterized by unique rock outcroppings, sandstone hogbacks, open meadows, shrubby hillsides, and ponderosa pine forests. Validation methods included comparison with high resolution ground based lidar scans, high-accuracy ground control points (GCPs) established using GNSS surveys. Uncrewed systems based lidar scans, etc. Novel check point targets (such as manhole covers, which represent dark objects in highly reflective vegetated fields) etc. were studied.Washington (Coastal and Diverse Forest): The second case study covered dense forest canopies of north western Washington, which encompass a range of coastal and forested environments and temperate rainforests. In this case, the validation methods involved high resolution ground-based laser scan data, data from total stations, surveying natural targets such as tree trunks, etc.Overall, the goal of the study was to understand lidar’s effectiveness in generating high-quality elevation models across various landscapes. Novel checkpoint targets were developed to improve the accuracy assessment in complex terrains. The integration of terrestrial lidar scanning and total station surveys, low flying uncrewed aerial systems based lidar data as validation tools offers a promising approach to improving the accuracy and reliability of aerial lidar data, particularly in challenging environments.
Jeffrey Irwin, US Geological Survey, EROS Data Center
3:00 – 3:15 PM – USGS’s 3D Hydrography Program: Going Beyond the Line
USGS is undertaking a program to update the nation’s hydrography from the current National Hydrography Dataset (NHD) to the 3D Hydrography Program (3DHP). The 3DHP is derived from USGS’s 3D Elevation Program (3DEP) lidar in CONUS and IfSAR in Alaska. The program developed detailed specifications for the dataset in order to ensure a high quality and consistent data-set. Although the underlying principles of water flow over landscapes are simple, the variation of landscapes across the US require significant understanding in order to produce a hydrography dataset that both represents reality and fits the specifications of the USGS specifications. Although USGS requires the creation of linework that comprises the river network, many users require more information for their programs than is required by the standard 3DHP schema. This presentation uses examples from Michigan, Missouri, Alaska, Texas, Washington, Pennsylvania and California to show what additional information can be extracted from the source lidar data and other datasets that can help agencies manage their water resources and meet their operational requirements.
Andrew Brenner, NV5 Geospatial Inc.
3:15 – 3:30 PM – Enhancing 3DEP with Topobathymetric Lidar: A Comparative Analysis of Leica Chiroptera-5 and Riegl VQ-880-G+ for Riverine Applications
In August 2023, NV5 Geospatial (NV5) was contracted by United States Geological Survey (USGS) to collect topobathymetric lidar data and digital imagery in the late summer of 2023 during low flow conditions for a stretch of the Chehalis River in Washington. The project supports the assessment of topobathy lidar data collection of rivers for the 3DEP program. Project goals focus on mapping the channel morphology which will support efforts like salmon and steelhead habitat restoration and inundation modeling. The project utilized a Leica Chiroptera-5 lidar sensor to collect bathymetric data, achieving Quality Level 2b (QL2b) elevation data. Additionally, a Riegl VQ-880-G+ sensor was deployed over part of the project area. Both sensors were installed on the same aircraft, allowing for simultaneous data collection during a single flight. This dual-sensor approach facilitates a direct comparison of the Riegl VQ-880-G+ sensor’s performance against the Chiroptera-5 sensor used for primary data collection. This presentation will highlight the comparative analysis of these sensors’ performance in capturing topobathymetric data.
Lara Heitmeyer, NV5 Geospatial Inc.
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