VTK中顶点和点之间的差异 [英] Difference between vertex and point in vtk

问题描述

VTK 中的顶点和点之间的主要区别是什么？

What's the main difference between a vertex and a point in VTK?

好吧，我正在为 vtkPolyData 输出：

Well, I was assigning some computed points to an vtkPolyData output:

vtkPolyData* oput = vtkPolyData::SafeDownCast(out_info->Get(vtkDataObject::DATA_OBJECT()));

，我想知道是否使用方法 SetVerts（vtkCellArray * v）或方法 SetPoints（vtkPoints *）。

and I wondered whether to use the method SetVerts(vtkCellArray *v) or the method SetPoints(vtkPoints *).

推荐答案

在VTK数据集中（即继承vtkDataSet的类，vtkDataSet是提供点概念的最简单的数据类型），点只是空间中的位置。数据可以存储在代表点轨迹的空间中或单元（例如三角形或四面体）上的位置处。储存在储存格中的值在储存格位置的每个点都具有相同的值。

In VTK datasets (i.e., classes inheriting vtkDataSet which is the simplest type of data that provides a notion of points), points are simply locations in space. Data may be stored at locations in space or on cells (e.g., triangles or tetrahedra) that represent a locus of points. Values stored on cells take on the same value at every point in the cell's locus.

单元格由其角点定义。在vtkPolyData中，每个单元格都是由vtkPoints实例中点坐标中的整数偏移量列表定义的。

Cells are defined by their corner points. In vtkPolyData, every cell is defined by a list of integer offsets into the point coordinates in a vtkPoints instance.

VTK中的顶点是其点轨迹为单个的单元格点。

A vertex in VTK is a cell whose point locus is a single point.

有可能在VTK数据集中明确列出任何点都未引用的点（例如，您可以在vtkPoints对象中指定点坐标不用作任何四面体，三角形或顶点单元的角点）。这些点只能具有点数据（由数组存储在由vtkDataSet保留的vtkPointData实例中），而不能具有单元格数据（由数组存储在由vtkDataSet保留的vtkCellData实例中）。

It is possible to have points listed explicitly in a VTK dataset which are not reference by any cell (e.g., you can specify point coordinates in a vtkPoints object that are not used as corner points for any tetrahedron, triangle, or vertex cell). These points can only have point data (stored by arrays in a vtkPointData instance held by the vtkDataSet) and not cell data (stored by arrays in a vtkCellData instance held by the vtkDataSet).

因此，通过 SetPoints（），您可以提供vtkCellArray实例随后引用的点坐标，以定义各种形状的点位置。一类形状是顶点（因此 SetVerts（）），而其他类型包括线和折线（ SetLines（））和三角形/四边形（ SetPolys（））。

So, SetPoints() lets you provide point coordinates which vtkCellArray instances then reference to define point locii of various shapes. One category of shapes is vertices (hence SetVerts()) while others include lines and polylines (SetLines()) and triangles/quads (SetPolys()).

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