使用vtkArrayCalculator生成向量场后渲染Glyph2D报错，求解决方案

问题 #

我正在尝试可视化螺旋桨的尾流场，场数据为Tecplot格式，包含u、v、w三个标量字段。通过vtkTecplotReader加载数据后，计划用vtkArrayCalculator生成由v、w组成的向量场，再通过Glyph2D完成可视化。代码如下：

vtkTecplotReader reader = new vtkTecplotReader();
reader.SetFileName("wake.dat");
reader.Update();

vtkMultiBlockDataSet multiBDS = new vtkMultiBlockDataSet();
multiBDS = reader.GetOutput();

// vector glyph
vtkArrayCalculator calculator = new vtkArrayCalculator();
for (uint i = 0; i < multiBDS.GetNumberOfBlocks(); i++)
{
    vtkPointSet block;
    if (multiBDS.GetBlock(i).IsA("vtkStructuredGrid") == 1)
    {
        block = multiBDS.GetBlock(i) as vtkStructuredGrid;
    }
    else
    {
        block = multiBDS.GetBlock(i) as vtkUnstructuredGrid;
    }
    calculator.AddInputData(block);
}

calculator.AddScalarArrayName("u", 0);
calculator.AddScalarArrayName("v", 0);
calculator.AddScalarArrayName("w", 0);
calculator.SetFunction("jHat*v + kHat*w");
calculator.SetResultArrayName("wake");
calculator.Update();

vtkGlyph2D glyph2D = new vtkGlyph2D();
glyph2D.SetSourceConnection(calculator.GetOutputPort());
glyph2D.Update();

vtkPolyDataMapper glyph2DMapper = new vtkGlyph2D();
glyph2DMapper.SetInputConnection(glyph2D.GetOutputPort());
glyph2DMapper.Update();

vtkActor glyph2DActor = new vtkActor();
glyph2DActor.SetMapper(glyph2DMapper);
glyph2DActor.GetProperty().SetColor(0, 0, 0);

运行时出现以下警告：

vtkDemandDrivenPipeline:677    ERR| vtkCompositeDataPipeline (0000024358F719B0): Input port 0 of algorithm vtkGlyph2D (0000024358F22C10) has 0 connections but is not optional

解决建议 #

• 合并多块数据集：
  vtkArrayCalculator不支持直接添加多个vtkPointSet输入，需先将多块数据合并为单一数据集。使用vtkAppendFilter完成合并：

  vtkAppendFilter append = new vtkAppendFilter();
  for (uint i = 0; i < multiBDS.GetNumberOfBlocks(); i++)
  {
      vtkPointSet block = multiBDS.GetBlock(i) as vtkPointSet;
      if (block != null)
      {
          append.AddInputData(block);
      }
  }
  append.Update();
  
  // 将合并后的数据集传给ArrayCalculator
  calculator.SetInputData(append.GetOutput());
  

• 补充vtkGlyph2D的源图形输入：
  vtkGlyph2D需要两个核心输入：带向量场的点数据集，以及用于可视化的2D图形源（如箭头）。当前代码缺少源图形，导致端口连接异常。添加源图形的示例代码：

  // 创建2D箭头作为glyph的可视化源
  vtkArrowSource arrow = new vtkArrowSource();
  arrow.Update();
  
  vtkGlyph2D glyph2D = new vtkGlyph2D();
  glyph2D.SetInputConnection(calculator.GetOutputPort()); // 设置点数据集输入
  glyph2D.SetSourceConnection(arrow.GetOutputPort()); // 设置glyph图形源
  glyph2D.SetVectorModeToUseVector(); // 指定使用生成的"wake"向量场
  glyph2D.SetScaleFactor(0.1); // 根据数据范围调整缩放比例
  glyph2D.Update();
  

• 修正Mapper类型错误：
  代码中vtkPolyDataMapper glyph2DMapper = new vtkGlyph2D();是类型错误，需改为正确的vtkPolyDataMapper实例：

  vtkPolyDataMapper glyph2DMapper = new vtkPolyDataMapper();
  

• 校验数组名称一致性：
  确保AddScalarArrayName中的字段名与Tecplot文件中的标量名完全匹配（大小写敏感），避免因名称不匹配导致向量场生成失败。

内容的提问来源于stack exchange，提问作者Seong