lightningtrace
Quickly contour a digital elevation model (DEM) using rasterio and matplotlib.
Install
Just use pip.
pip install lightningtrace
Example
The following example generates contours from the DEM at specified elevations. The extract_contours() function is a generator that yields GeoJSON features.
import rasterio
import geopandas as gp
import lightningtrace
with rasterio.open('data/dem.img', 'r') as rast:
# Generate the contours
contours_to_create = [1080, 1070, 1060, 1050, 1040, 1030, 1020, 1010]
contours = lightningtrace.contour.extract_contours(rast.read(1), rast.affine, contours_to_create)
# Create a Geopandas DataFrame from our contours
df = gp.GeoDataFrame.from_features(contours, rast.crs)
print df.head()
df.to_file('contours.shp')The library also has a few utility functions that make subsetting the raster easier and provide easy transformations between world and pixel coordinates. The result is a numpy array of (column, row) for each of the input coordinates.
import rasterio
from lightningtrace.transformations import world_to_pixel_coords
with rasterio.open('data/dem.img', 'r') as rast:
print world_to_pixel_coords(rast.affine, [(299721.936102, 129035.644049),])
# returns [(545.4898088852788, 516.4572418773387),]See the examples folder for more information.
License
MIT
Author
Michael Ewald, https://GeomaticsResearch.com
