Wedge Extraction

This example demonstrates how to extract a region using a geodesic wedge manifold.

📋 Summary

This example uses an unstructured Met Office LFRic C48 cubed-sphere mesh of surface altitude data.

Three separate geodesic wedge manifolds are constructed to extract the cells of the mesh contained within the wedge. Each wedge uses a different enclosure preference to extract the cells.

The regions extracted by each wedge are rendered along with the boundary where the manifold intersects the surface of the mesh. A different colour is used for each manifold boundary.

The red boundary contains only those cells where all points defining the face of a cell are within the manifold.

The purple boundary contains only those cells where at least one point that defines the face of the cell is within the manifold.

The orange boundary contains only those cells where the center of the cell is within the manifold.

Each of the extracted mesh regions contain quad cells and are constructed from CF UGRID unstructured cell points and connectivity. A Natural Earth base layer is also rendered along with Natural Earth coastlines.

Tags: component: coastlines component: manifold component: texture domain: orography sample: unstructured

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Static Scene

Interactive Scene

from __future__ import annotations

import geovista as gv
from geovista.geodesic import wedge
from geovista.pantry.meshes import lfric_orog
import geovista.theme


def main() -> None:
    """Extract and plot 3 wedge regions, each using different enclosure methods.

    Notes
    -----
    .. versionadded:: 0.6.0

    """
    # Load the sample mesh.
    mesh = lfric_orog()

    # Calculate the sample data range.
    clim = mesh.get_data_range()

    # Create 3 different wedge geodesic bounding-box manifolds.
    bbox_1 = wedge(-25, 25)
    bbox_2 = wedge(65, 115)
    bbox_3 = wedge(155, 205)

    # Extract the underlying sample mesh within each manifold using a different
    # preference which defines the criterion of sample mesh cell enclosure.
    region_1 = bbox_1.enclosed(mesh, preference="cell")
    region_2 = bbox_2.enclosed(mesh, preference="point")
    region_3 = bbox_3.enclosed(mesh, preference="center")

    p = gv.GeoPlotter()

    # Add the 3 extracted regions.
    sargs = {"title": "Surface Altitude / m", "fmt": "%.0f"}
    p.add_mesh(region_1, clim=clim, scalar_bar_args=sargs)
    p.add_mesh(region_2, clim=clim, scalar_bar_args=sargs)
    p.add_mesh(region_3, clim=clim, scalar_bar_args=sargs)

    # Add the surface boundary of each wedge region.
    p.add_mesh(bbox_1.boundary(mesh), color="red", line_width=3)
    p.add_mesh(bbox_2.boundary(mesh), color="purple", line_width=3)
    p.add_mesh(bbox_3.boundary(mesh), color="orange", line_width=3)

    # Add coastlines and a texture mapped base layer.
    p.add_base_layer(texture=gv.natural_earth_hypsometric())
    p.add_coastlines(resolution="10m")

    # Define a specific camera position.
    p.view_vector(vector=(1, 1, 1))
    p.camera.zoom(1.2)

    p.show_axes()
    p.show()


if __name__ == "__main__":
    main()