Plotter Extraction

This example demonstrates how to streamline geometry extraction within a plotter.

📋 まとめ

This example uses an unstructured DYNAMICO icosahedral unstructured mesh of Surface Air Pressure data located on hexagonal/pentagonal faces/cells.

A geodesic bounding-box manifold (BBox) is constructed for the cubed-sphere Arctic panel. Note that the boundary where this manifold intersects the surface of the earth is highlighted in gold.

Global geometries are added to the plotter first before the bounding-box manifold is then used by the plotter to automatically extract geometries added to the scene.

The behaviour of the extraction is controlled through the preference and outside propetries of the bounding-box manifold. These properties define the extraction membership criterion of a mesh cell and whether cells inside or outside the manifold are selected.

A threshold is applied to the Surface Air Pressure mesh prior to extraction, and Natural Earth coastlines and texture mapped Natural Earth base layers of different colours and types are rendered inside and outside the Arctic cubed-sphere panel to reinforce the region of interest.

ヒント

A GeoPlotter instance may be created using the manifold keyword argument e.g.,

import geovista
from geovista.geodesic import panel

p = geovista.GeoPlotter(manifold=panel("africa"))

🏷 Tags: component: coastlines component: graticule component: manifold component: texture filter: threshold plot: anti-aliasing plot: camera sample: unstructured version: 0.6.0 widget: north-arrow

---

Static Scene

Interactive Scene

from __future__ import annotations

import geovista as gv
from geovista.geodesic import panel
from geovista.pantry.meshes import dynamico


def main() -> None:
    """Demonstrate automated manifold extraction of plotter geometries.

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

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

    # Generate the geodesic bounding-box manifold for the arctic
    # cubed-sphere panel.
    bbox = panel("arctic")

    p = gv.GeoPlotter()

    # Render a global NASA Black Marble "night lights" texture
    # and highlight the bounding-box manifold boundary.
    p.add_base_layer(texture=gv.black_marble())
    p.add_mesh(bbox.boundary(), color="gold", line_width=2)

    # Add the bounding-box manifold to the plotter which will
    # automatically extract geometries added to the scene.
    p.manifold = bbox
    p.add_base_layer(texture=gv.natural_earth_1())

    # Change the bounding-box manifold extraction criterion
    # from cell "center" (default) to the entire mesh "cell".
    p.manifold.preference = "cell"

    # Extract and render the coastlines, meridians, parallels and the
    # DYNAMICO icosahedral mesh (thresholded) enclosed by the manifold.
    sargs = {"title": "Surface Air Pressure / Pa", "fmt": "%.0f"}
    p.add_mesh(mesh.threshold(1e5, invert=True), cmap="diff", scalar_bar_args=sargs)
    p.add_graticule(factor=2, mesh_args={"line_width": 2})
    p.add_coastlines()

    # Now extract geometries "outside" the manifold rather than "inside".
    p.manifold.outside = True
    p.add_coastlines(color="gold")

    # Render the scene with fast approximate anti-aliasing.
    p.enable_anti_aliasing(aa_type="fxaa")

    # Define a specific camera position.
    p.view_xy()
    p.camera.zoom(1.7)

    p.add_north_arrow_widget()
    p.show()


if __name__ == "__main__":
    main()