Package: gradeit
GradeITRoad Grade Inference Tool (GradeIT) - a python package, developed by the National Renewable Energy Laboratory,
to append elevation and road grade to a sequence of GPS points.OverviewGradeIT looks up and filters elevation and derives road grade from theUSGS Digital Elevation Modelto append to GPS points, typically
for vehicles traveling on paved roads. The python package offers options to use either the the freely accessible USGSElevation Point Query Serviceor a locally available raster database of the elevation
model, which provides much faster results.SetupClone or download the git repository.git clone https://github.com/NREL/gradeit.gitgradeit depends on python 3.8 and up. One way to satisfy this is to use conda:condacreate-ngradeitpython=3.8
condaactivategradeitThis will create a new conda environment that uses python 3.8.Then, you can install the gradeit librarypip install gradeitor if you're already in the gradeit root directory then:pip install .Getting StartedIn this repository,docs/demo.pywill demonstrate the most basic application of the gradeit package. Additionally, thegradeit-notebooksrepo contains various Jupyter notebooks that demonstrate gradeit applications and explore potential improvements.USGS Elevation DataThe United States Geological Survey offers a variety of products as a part of theNational Mapproject, including bare-earth elevation datasets. The 1/3 arc-second elevation dataset is continuous for the coterminous United States and is therefore used in GradeIT. As shown indocs/demo.ipynbappending elevation and grade to 1000+ points benefits significantly from having a local or network copy of the required USGS elevation data.NREL has the 1/3 arc-second raster data downloaded to on-site compute resources for large scale needs. Individual users can access the same raster datahere.Download ScriptThis repository comes with a script you can use to download all of the tiles. You can use the script like this:exportOUTPUT_DIR=path/to/output/
pythonscripts/get_usgs_tiles.pyThe script will then proceed to download all tiles intopath/to/output/which can be used when running gradeit:results=gradeit(df=df,source="usgs-local",usgs_db_path="path/to/output/",)FiltersGiven the spatial noise that can be present in GPS data and the 1/3 arc-second resolution of the digital elevation
model being employed, outliers and unrealistic topographical features can be present in the raw elevation profiles.
Therefore, a series of filtering procedures can be applied to the elevation data, if desired by the user. The primary
filter procedure is summarized in the figure below from Wood et al in 2014.Wood, Eric, E. Burton, A. Duran, and J. Gonder. Appending High-Resolution Elevation Data to GPS Speed Traces for
Vehicle Energy Modeling and Simulation. No. NREL/TP-5400-61109. National Renewable Energy Lab.(NREL), Golden, CO
(United States), 2014.Additionally, since the USGS Digital Elevation Model is a "bare earth" model, road infrastructure features (i.e.
bridges and overpasses) are often not represented in the data. Rather, the "bare earth" model represents the valley or
body of water that is being spanned. GradeIT has optional filtering routines to explicitly handle this by
"building" a bridge to span the river, valley, etc where necessary.