sample.py 文件源码

def getProjectedShapes(shapes, xmin, xmax, ymin, ymax):
    """
    Take a sequence of geographic shapes and project them to a bounds-centered
    orthographic projection.

    Args:
        shapes: Sequence of shapes, as read in by fiona.collection().
        xmin: Eastern boundary of all shapes.
        xmax: Western boundary of all shapes.
        ymin: Southern boundary of all shapes.
        ymax: Northern boundary of all shapes.

    Returns:
       Tuple of
           - Input sequence of shapes, projected to orthographic
           - PyProj projection object used to transform input shapes
    """
    latmiddle = ymin + (ymax - ymin) / 2.0
    lonmiddle = xmin + (xmax - xmin) / 2.0
    projstr = ('+proj=ortho +datum=WGS84 +lat_0=%.4f +lon_0=%.4f '
               '+x_0=0.0 +y_0=0.0' % (latmiddle, lonmiddle))
    proj = pyproj.Proj(projparams=projstr)
    project = partial(
        pyproj.transform,
        pyproj.Proj(proj='latlong', datum='WGS84'),
        proj)

    pshapes = []
    for tshape in shapes:
        if tshape['geometry']['type'] == 'Polygon':
            pshapegeo = shape(tshape['geometry'])
        else:
            pshapegeo = shape(tshape['geometry'])
        pshape = transform(project, pshapegeo)
        pshapes.append(pshape)  # assuming here that these are simple polygons

    return (pshapes, proj)