ElevationBandsWithGlyphs.py

#!/usr/bin/env python

from __future__ import print_function

import math

import vtk

# Available surfaces are:
SURFACE_TYPE = {"PLANE", "SPHERE", "PARAMETRIC_SURFACE"}


def WritePNG(ren, fn, magnification=1):
    """
    Save the image as a PNG
    :param: ren - the renderer.
    :param: fn - the file name.
    :param: magnification - the magnification, usually 1.
    """
    renLgeIm = vtk.vtkRenderLargeImage()
    imgWriter = vtk.vtkPNGWriter()
    renLgeIm.SetInput(ren)
    renLgeIm.SetMagnification(magnification)
    imgWriter.SetInputConnection(renLgeIm.GetOutputPort())
    imgWriter.SetFileName(fn)
    imgWriter.Write()


def MakeBands(dR, numberOfBands, nearestInteger):
    """
    Divide a range into bands
    :param: dR - [min, max] the range that is to be covered by the bands.
    :param: numberOfBands - the number of bands, a positive integer.
    :param: nearestInteger - if True then [floor(min), ceil(max)] is used.
    :return: A List consisting of [min, midpoint, max] for each band.
    """
    bands = list()
    if (dR[1] < dR[0]) or (numberOfBands <= 0):
        return bands
    x = list(dR)
    if nearestInteger:
        x[0] = math.floor(x[0])
        x[1] = math.ceil(x[1])
    dx = (x[1] - x[0]) / float(numberOfBands)
    b = [x[0], x[0] + dx / 2.0, x[0] + dx]
    i = 0
    while i < numberOfBands:
        bands.append(b)
        b = [b[0] + dx, b[1] + dx, b[2] + dx]
        i += 1
    return bands


def MakeIntegralBands(dR):
    """
    Divide a range into integral bands
    :param: dR - [min, max] the range that is to be covered by the bands.
    :return: A List consisting of [min, midpoint, max] for each band.
    """
    bands = list()
    if dR[1] < dR[0]:
        return bands
    x = list(dR)
    x[0] = math.floor(x[0])
    x[1] = math.ceil(x[1])
    numberOfBands = int(abs(x[1]) + abs(x[0]))
    return MakeBands(x, numberOfBands, False)


def MakeElevations(src):
    """
    Generate elevations over the surface.
    :param: src - the vtkPolyData source.
    :return: - vtkPolyData source with elevations.
    """
    bounds = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
    src.GetBounds(bounds)
    elevFilter = vtk.vtkElevationFilter()
    elevFilter.SetInputData(src)
    elevFilter.SetLowPoint(0, bounds[2], 0)
    elevFilter.SetHighPoint(0, bounds[3], 0)
    elevFilter.SetScalarRange(bounds[2], bounds[3])
    elevFilter.Update()
    return elevFilter.GetPolyDataOutput()


def MakePlane():
    """
    Make a plane as the source.
    :return: vtkPolyData with normal and scalar data.
    """
    source = vtk.vtkPlaneSource()
    source.SetOrigin(-10.0, -10.0, 0.0)
    source.SetPoint2(-10.0, 10.0, 0.0)
    source.SetPoint1(10.0, -10.0, 0.0)
    source.SetXResolution(20)
    source.SetYResolution(20)
    source.Update()
    return MakeElevations(source.GetOutput())


def MakeSphere():
    """
    Make a sphere as the source.
    :return: vtkPolyData with normal and scalar data.
    """
    source = vtk.vtkSphereSource()
    source.SetCenter(0.0, 0.0, 0.0)
    source.SetRadius(10.0)
    source.SetThetaResolution(32)
    source.SetPhiResolution(32)
    source.Update()
    return MakeElevations(source.GetOutput())


def MakeParametricSource():
    """
    Make a parametric surface as the source.
    :return: vtkPolyData with normal and scalar data.
    """
    fn = vtk.vtkParametricRandomHills()
    fn.AllowRandomGenerationOn()
    fn.SetRandomSeed(1)
    fn.SetNumberOfHills(30)
    # Make the normals face out of the surface.
    # Not needed with VTK 8.0 or later.
    # if fn.GetClassName() == 'vtkParametricRandomHills':
    #    fn.ClockwiseOrderingOff()
    source = vtk.vtkParametricFunctionSource()
    source.SetParametricFunction(fn)
    source.SetUResolution(50)
    source.SetVResolution(50)
    source.SetScalarModeToZ()
    source.Update()
    # Name the arrays (not needed in VTK 6.2+ for vtkParametricFunctionSource)
    source.GetOutput().GetPointData().GetNormals().SetName('Normals')
    source.GetOutput().GetPointData().GetScalars().SetName('Scalars')
    return source.GetOutput()


def MakeLUT():
    """
    Make a lookup table using vtkColorSeries.
    :return: An indexed lookup table.
    """
    # Make the lookup table.
    colorSeries = vtk.vtkColorSeries()
    # Select a color scheme.
    # colorSeriesEnum = colorSeries.BREWER_DIVERGING_BROWN_BLUE_GREEN_9
    # colorSeriesEnum = colorSeries.BREWER_DIVERGING_SPECTRAL_10
    # colorSeriesEnum = colorSeries.BREWER_DIVERGING_SPECTRAL_3
    # colorSeriesEnum = colorSeries.BREWER_DIVERGING_PURPLE_ORANGE_9
    # colorSeriesEnum = colorSeries.BREWER_SEQUENTIAL_BLUE_PURPLE_9
    # colorSeriesEnum = colorSeries.BREWER_SEQUENTIAL_BLUE_GREEN_9
    colorSeriesEnum = colorSeries.BREWER_QUALITATIVE_SET3
    # colorSeriesEnum = colorSeries.CITRUS
    colorSeries.SetColorScheme(colorSeriesEnum)
    lut = vtk.vtkLookupTable()
    colorSeries.BuildLookupTable(lut)
    lut.SetNanColor(1, 0, 0, 1)
    return lut


def ReverseLUT(lut):
    """
    Create a lookup table with the colors reversed.
    :param: lut - An indexed lookup table.
    :return: The reversed indexed lookup table.
    """
    lutr = vtk.vtkLookupTable()
    lutr.DeepCopy(lut)
    t = lut.GetNumberOfTableValues() - 1
    revList = reversed(list(range(t + 1)))
    for i in revList:
        rgba = [0, 0, 0]
        v = float(i)
        lut.GetColor(v, rgba)
        rgba.append(lut.GetOpacity(v))
        lutr.SetTableValue(t - i, rgba)
    t = lut.GetNumberOfAnnotatedValues() - 1
    revList = reversed(list(range(t + 1)))
    for i in revList:
        lutr.SetAnnotation(t - i, lut.GetAnnotation(i))
    return lutr


def Frequencies(bands, src):
    """
    Count the number of scalars in each band.
    :param: bands - the bands.
    :param: src - the vtkPolyData source.
    :return: The frequencies of the scalars in each band.
    """
    freq = dict()
    for i in range(len(bands)):
        freq[i] = 0
    tuples = src.GetPointData().GetScalars().GetNumberOfTuples()
    for i in range(tuples):
        x = src.GetPointData().GetScalars().GetTuple1(i)
        for j in range(len(bands)):
            if x <= bands[j][2]:
                freq[j] = freq[j] + 1
                break
    return freq


def MakeGlyphs(src, reverseNormals):
    """
    Glyph the normals on the surface.

    You may need to adjust the parameters for maskPts, arrow and glyph for a
    nice appearance.

    :param: src - the surface to glyph.
    :param: reverseNormals - if True the normals on the surface are reversed.
    :return: The glyph object.

    """
    # Sometimes the contouring algorithm can create a volume whose gradient
    # vector and ordering of polygon (using the right hand rule) are
    # inconsistent. vtkReverseSense cures this problem.
    reverse = vtk.vtkReverseSense()

    # Choose a random subset of points.
    maskPts = vtk.vtkMaskPoints()
    maskPts.SetOnRatio(5)
    maskPts.RandomModeOn()
    if reverseNormals:
        reverse.SetInputData(src)
        reverse.ReverseCellsOn()
        reverse.ReverseNormalsOn()
        maskPts.SetInputConnection(reverse.GetOutputPort())
    else:
        maskPts.SetInputData(src)

    # Source for the glyph filter
    arrow = vtk.vtkArrowSource()
    arrow.SetTipResolution(16)
    arrow.SetTipLength(0.3)
    arrow.SetTipRadius(0.1)

    glyph = vtk.vtkGlyph3D()
    glyph.SetSourceConnection(arrow.GetOutputPort())
    glyph.SetInputConnection(maskPts.GetOutputPort())
    glyph.SetVectorModeToUseNormal()
    glyph.SetScaleFactor(1)
    glyph.SetColorModeToColorByVector()
    glyph.SetScaleModeToScaleByVector()
    glyph.OrientOn()
    glyph.Update()
    return glyph


def DisplaySurface(st):
    """
    Make and display the surface.
    :param: st - the surface to display.
    :return The vtkRenderWindowInteractor.
    """
    surface = st.upper()
    if not (surface in SURFACE_TYPE):
        print(st, "is not a surface.")
        iren = vtk.vtkRenderWindowInteractor()
        return iren
    # ------------------------------------------------------------
    # Create the surface, lookup tables, contour filter etc.
    # ------------------------------------------------------------
    src = vtk.vtkPolyData()
    if surface == "PLANE":
        src = MakePlane()
    elif surface == "SPHERE":
        src = MakeSphere()
    elif surface == "PARAMETRIC_SURFACE":
        src = MakeParametricSource()
        # The scalars are named "Scalars"by default
        # in the parametric surfaces, so change the name.
        src.GetPointData().GetScalars().SetName("Elevation")
    scalarRange = src.GetScalarRange()

    lut = MakeLUT()
    lut.SetTableRange(scalarRange)
    numberOfBands = lut.GetNumberOfTableValues()
    # bands = MakeIntegralBands(scalarRange)
    bands = MakeBands(scalarRange, numberOfBands, False)

    # Let's do a frequency table.
    # The number of scalars in each band.
    # print Frequencies(bands, src)

    # We will use the midpoint of the band as the label.
    labels = []
    for i in range(len(bands)):
        labels.append('{:4.2f}'.format(bands[i][1]))

    # Annotate
    values = vtk.vtkVariantArray()
    for i in range(len(labels)):
        values.InsertNextValue(vtk.vtkVariant(labels[i]))
    for i in range(values.GetNumberOfTuples()):
        lut.SetAnnotation(i, values.GetValue(i).ToString())

    # Create a lookup table with the colors reversed.
    lutr = ReverseLUT(lut)

    # Create the contour bands.
    bcf = vtk.vtkBandedPolyDataContourFilter()
    bcf.SetInputData(src)
    # Use either the minimum or maximum value for each band.
    for i in range(0, numberOfBands):
        bcf.SetValue(i, bands[i][2])
    # We will use an indexed lookup table.
    bcf.SetScalarModeToIndex()
    bcf.GenerateContourEdgesOn()

    # Generate the glyphs on the original surface.
    glyph = MakeGlyphs(src, False)

    # ------------------------------------------------------------
    # Create the mappers and actors
    # ------------------------------------------------------------
    srcMapper = vtk.vtkPolyDataMapper()
    srcMapper.SetInputConnection(bcf.GetOutputPort())
    srcMapper.SetScalarRange(scalarRange)
    srcMapper.SetLookupTable(lut)
    srcMapper.SetScalarModeToUseCellData()

    srcActor = vtk.vtkActor()
    srcActor.SetMapper(srcMapper)
    srcActor.RotateX(-45)
    srcActor.RotateZ(45)

    # Create contour edges
    edgeMapper = vtk.vtkPolyDataMapper()
    edgeMapper.SetInputData(bcf.GetContourEdgesOutput())
    edgeMapper.SetResolveCoincidentTopologyToPolygonOffset()

    edgeActor = vtk.vtkActor()
    edgeActor.SetMapper(edgeMapper)
    edgeActor.GetProperty().SetColor(0, 0, 0)
    edgeActor.RotateX(-45)
    edgeActor.RotateZ(45)

    glyphMapper = vtk.vtkPolyDataMapper()
    glyphMapper.SetInputConnection(glyph.GetOutputPort())
    glyphMapper.SetScalarModeToUsePointFieldData()
    glyphMapper.SetColorModeToMapScalars()
    glyphMapper.ScalarVisibilityOn()
    glyphMapper.SelectColorArray('Elevation')
    # Colour by scalars.
    glyphMapper.SetScalarRange(scalarRange)

    glyphActor = vtk.vtkActor()
    glyphActor.SetMapper(glyphMapper)
    glyphActor.RotateX(-45)
    glyphActor.RotateZ(45)

    # Add a scalar bar.
    scalarBar = vtk.vtkScalarBarActor()
    # scalarBar.SetLookupTable(lut)
    # Use this LUT if you want the highest value at the top.
    scalarBar.SetLookupTable(lutr)
    scalarBar.SetTitle('Elevation (m)')

    # ------------------------------------------------------------
    # Create the RenderWindow, Renderer and Interactor
    # ------------------------------------------------------------
    ren = vtk.vtkRenderer()
    renWin = vtk.vtkRenderWindow()
    iren = vtk.vtkRenderWindowInteractor()

    renWin.AddRenderer(ren)
    iren.SetRenderWindow(renWin)

    # add actors
    ren.AddViewProp(srcActor)
    ren.AddViewProp(edgeActor)
    ren.AddViewProp(glyphActor)
    ren.AddActor2D(scalarBar)

    ren.SetBackground(0.7, 0.8, 1.0)
    renWin.SetSize(800, 800)
    renWin.Render()

    ren.GetActiveCamera().Zoom(1.5)

    return iren


if __name__ == '__main__':
    # iren = DisplaySurface("PLANE")
    # iren = DisplaySurface("SPHERE")
    iren = DisplaySurface("PARAMETRIC_SURFACE")
    iren.Render()
    iren.Start()
    # WritePNG(iren.GetRenderWindow().GetRenderers().GetFirstRenderer(),
    #               "ElevationBandsWithGlyphs.png")