LiDAR-based elevation and hydrology comparison
The data include layers that have been saved as a Quantum GIS (free software) map project so all you need to do is open the project in Quantum. Quantum can be downloaded from the Quantum (user-friendly) page in the GIS software folder; instructions to open Quantum GIS projects are in the About downloading page in theAgriculture Custom Downloads folder. It is not necessary to use Quantum GIS (layers will open in other software such as ArcGIS).
To download, left-click, then click OK to save file to your computer. The file will be in a compressed format; there are steps describing how to extract the data within the compressed (zipped) files in the About Downloading page.
Data download:
IMPORTANT: MAJOR INTERNET BROWSERS HAVE RECENTLY UPGRADED SECURITY FOR DOWNLOADING DATA FROM WEBSITES. If your browser has a security risk message when attempting to download a file below (or any file on this website), you can complete a download security risk check by: 1) copying the download URL by right-clicking on the download then clicking Copy Link, 2) accessing virustotal.com (parent company is Google; opens in new tab) then clicking the URL tab, 3) pasting the download URL into the search box then clicking the magnifying glass to start the download security risk search. Of course, use the download security check website or tool of your choice.
Data Description and Map Image
LiDAR-based elevation and derived hydrology comparison: Includes a comparison between LiDAR-based elevation rasters and derived layers (for the same extent) from Ohio Geographically Reference Information Program (OGRIP) with 2.5 foot resolution, a further smoothed OGRIP grid with 2.5 foot resolution, and another layer from The USGS National Map Seamless Data Viewer (USGS) that has been projected to an 11.2 foot resolution. The USGS acquires LiDAR-based elevation from different sources, works with it to improve it, then projects it to approximately a 3-meter average resolution. National Map data spatial reference upon download is in NAD83 geographical coordinate system, as a result pixels have different length north-south and east-west sides until projected into a UTM or state plane system; the average dimension of the pixels is about 3 x 3 meters though. For comparison purposes of elevation at different resolutions here, the data was projected to an 11.2 foot resolution with bilinear interpolation;; each National Map-based pixel is 20 times larger in area than the OGRIP pixels. For comparison purposes of elevation at different resolutions here, the data was projected to 11.2 foot resolution; each National Map-based pixel is 20 times larger in area than the OGRIP pixels. The map projects includes the following layers with area and other attributes: basin boundaries, flow accumulation, and sinks (includes cubic yards of volume).
Screen capture when opening map in free Quantum GIS
