Distance operations

Computing distance between sets of geospatial data or manipulating their shape based on distance is often important for later analysis. To facilitate this type of operations, GeoUtils implements distance-specific functionalities for both vectors and rasters.

Tip

It is often important to compute distances in a metric CRS. For this, reproject (with reproject()) to a local metric CRS (that can be estimated with get_metric_crs()).

Proximity

Proximity corresponds to the distance to the closest target geospatial data, computed on each pixel of a raster’s grid. The target geospatial data can be either a vector or a raster.

geoutils.Raster.proximity() and geoutils.Vector.proximity()

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import matplotlib.pyplot as plt
import geoutils as gu
import numpy as np

rast = gu.Raster(gu.examples.get_path("everest_landsat_b4"))
rast.set_nodata(0)  # Annoying to have to do this here, should we update it in the example?
vect = gu.Vector(gu.examples.get_path("everest_rgi_outlines"))

# Compute proximity to vector outlines
proximity = vect.proximity(rast)

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f, ax = plt.subplots(1, 2)
ax[0].set_title("Raster and vector")
rast.plot(ax=ax[0], cmap="gray", add_cbar=False)
vect.plot(ref_crs=rast, ax=ax[0], ec="k", fc="none")
ax[1].set_title("Proximity")
proximity.plot(ax=ax[1], cmap="viridis", cbar_title="Distance to outlines (m)")
_ = ax[1].set_yticklabels([])
plt.tight_layout()

Buffering without overlap

Buffering consists in expanding or collapsing vector geometries equally in all directions. However, this can often lead to overlap between shapes, which is sometimes undesirable. Using Voronoi polygons, we provide a buffering method without overlap.

geoutils.Vector.buffer_without_overlap()

# Compute buffer without overlap from vector exterior
vect_buff_nolap = vect.buffer_without_overlap(buffer_size=500)

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# Plot with color to see that the attributes are retained for every feature
vect.plot(ax="new", ec="k", column="Area", alpha=0.5, add_cbar=False)
vect_buff_nolap.plot(column="Area", cbar_title="Buffer around initial features\ncolored by glacier area (km)")