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Using Lidar

 

Lidar technology provides very precise, accurate, and high-resolution images of the surface of the earth, vegetation, and the built environment. Lidar is an essential tool in helping Oregon better understand natural hazards and resources, and also manage and plan enhancements to water systems, roads, open space, and ecosystems.

Lidar flood landslide PDX

landslide revealed by lidarLidar in Action: Geologic Hazard and Resource Mapping. DOGAMI uses lidar data in new-generation geologic hazard and resource mapping for an accurate, complete understanding of floods, landslides, tsunami, coastal erosion, geology, and water resource potential. For example, more landslides have been identified and mapped in the past five years with lidar than had been mapped in the previous 60 years. Land that has moved in the past is more likely to slide in the future – so accurate understanding of where landslides have occurred saves lives and protects property.

landslide revealed by lidarLidar in Action: Protecting and Planning for Roads. The Oregon Department of Transportation has identified multiple practical uses for using lidar to keep roads open and maintained, including managing landslide risks along the state highway system, prioritizing repair and preventive maintenance, and highway corridor planning and management.

landslide revealed by lidarLidar in Action: Identifying Agricultural Resources. Natural Resources Conservation Service mapped soils in Willamette, Wallowa, Grande Ronde, Baker, Yamhill, and Deschutes Valleys to help understand where prime farmland soils are located, and to provide farmers with useful information for optimizing drainage and irrigation.

More Uses of Lidar Data

Lidar offers an accurate, efficient, and cost-effective way to:  

  • Find landslides, old cuts and grades
  • Measure and estimate fills and cuts
  • Find stream channels, measure gradients
  • Measure the size and height of buildings, bridges
  • Locate and measure every tree in the forest
  • Characterize land cover
  • Model floods, fire behavior
  • Locate power lines and power poles
  • Support archeological investigations
  • Map wetlands and impervious surfaces
  • Define watersheds and viewsheds
  • Model insolation and shading
  • Map road center and sidelines
  • Find law enforcement targets
  • Map landforms and soils
  • Assess property remotely
  • Inventory carbon
  • Monitor quarries, find abandoned mines
  • Enhance any project that requires a detailed and accurate 2-D or 3-D map

How to Use Lidar: Resources for Technical Users

  • Where can I download lidar data?
    Use the DOGAMI Lidar Data Viewer or Lidar Data Quadrangles publications page. DOGAMI Lidar Data Quadrangle Series publications generally contain a standard set of data files: a bare earth digital elevation model (DEM), a highest hit DEM, and intensity tiff images, all in Esri grid format.  Metadata, readme, shapefiles, extents, and 7.5 and 1/100th quad index files are also included. All grid data have been tiled to USGS 7.5-minute quadrangles and referenced to Ohio Code (e.g., 45122D5 = Gladstone quadrangle). Intensity TIFFs have been tiled to 1/100th 7.5-minute quads and referenced to Ohio Code (e.g., 45122D5418). Typical DVD file size for an entire quadrangle is 2-4 GB. Learn more about Ohio Codes and LDQ series publications.

    Please note: Due to extremely large file sizes, point cloud data is not available via the Lidar Data Viewer. Point cloud data may be obtained by submitting a public records request to DOGAMI, or downloaded from:
      • Oregon State University: DOGAMI provides copies of raster and point cloud data to OSU for distribution on their public FTP site.
      • National Oceanic and Atmospheric Administration: DOGAMI provides copies of lidar point cloud data to NOAA for distribution on their Digital Coast website.

  • What software do I need to use lidar data?
    For rasters, users need GIS software that can read georeferenced rasters in .adf format (Esri grid) such as ArcGIS, IMAGINE, GeoMedia, etc. QGIS is an open source GIS software option that will support rasters. If the data are downloaded from a third party such as OpenTopography the data come in a variety of formats such as TIF, JPEG, IMAGINE, or Esri grid. 

  • What ways are there to view lidar data? 
    Lidar can be viewed as either mass points or a raster. The best method to view mass points (i.e., LAS files) is through a 3D point viewer, for example, the free U.S. Forest Service visualization system Fusion. Raster formatted data can be viewed as a digital elevation model (DEM) using a color ramp to expose variations in elevation. Many users create hillshades or slope rasters from the DEMs using GIS software. These derivative products allow for better visualization of surface features. 

  • Can I view lidar data in CAD software?
    Yes, both AutoCAD Civil 3D and Bentley Microstation support import of raster and LAS point data. It should be noted that LAS point datasets are typically very large and might operate slowly. Additionally, raster imports typically require changing settings. For instance, AutoCAD Civil 3D requires the user to specify ".adf" file format before the file can be viewed, and Bentley Microstation requires conversion of Esri grid format to TIFF or another image format to add rasters. 
  • Can contours be created from lidar data?
    Yes. Contours can be derived from lidar rasters using GIS software. 

  • What is the finest contour I can create?
    The appropriate contour interval for lidar is dependent on the size of the lidar ground footprint (diameter of the laser beam on the ground) and the accuracy of the lidar dataset being used. All OLC data support a 2-ft contour using American Society for Photogrammetry and Remote Sensing (ASPRS) standards for accuracy.

  • How can I overlay multiple DOGAMI layers?
    The easiest way to do this is to download layer data or use web services via the DOGAMI Geospatial Data and Web Services page.

(last updated 10/24/2018)

 

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