DEMGenerator

These input features may be 2D or 3D.Other than points, lines and area geometries, they may also be raster, point cloud, and aggregate geometries.

2D features will be forced to 3D by adding a z value of 0.In most cases, all points extracted from this port will be found in the vertex pool of the underlying surface model.A minimum of 3 unique points are required to construct a surface model.Points with duplicate x and y values will be dropped.

These input features may be 2D or 3D, and may reside inside an aggregate structure.

2D features will be forced to 3D by adding a z value of 0.Breakline edges will be found in the edge pool of the underlying surface model.Sometimes, a breakline edge will be split up to allow an optimal triangulation of the surface model.Points with duplicate x and y values will be dropped.

This output port samples the underlying surface model according to the sampling rates specified inOutput DEM X Cell Spacing, andOutput DEM Y Cell Spacing, and produces a set of evenly spaced 3D points.

This parameter allows groups to be formed by attribute values.Zero or more attributes may be specified.

可使ut features with the same attribute values are placed into the same group.The transformer then operates independently on each group of input features.

If this parameter is left blank, the transformer will treat the entire set of input features as one group.

过程在结束（封闭）: This is the default behavior.Processing will only occur in this transformer once all input is present.

过程当组更改（高级）: This transformer will process input groups in order.Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group.This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.

注意事项使用通过...分组

有使用两个典型原因过程当组更改（高级）。第一个是有意识地在组要被处理（并且已经如此命令）传入的数据。在这种情况下，结构使然集团通过使用 - 而不是性能方面的考虑。

第二个原因可能是潜在的性能提升。

性能提升是最有可能当数据已经排序（或使用阅读SQL ORDER BY声明），因为更少的工作需要FME的。如果数据需要排序，它可以在工作区中进行排序（虽然增加的处理开销可能会抵消任何收益）。

排序根据数据流的数目变得更困难。多个数据流可以几乎是不可能的排序到正确的顺序，因为所有的功能匹配通过...分组值需要到达之前的任何特征属于下一组（任何特征类型或数据集的）。在这种情况下，使用通过...分组同过程在结束（封闭）可能是等效的和简单的方法。

注意：多种要素类型和特点从多个数据集通常不会自然出现在正确的顺序。

如同许多情况下，在您的工作与你的数据测试不同的方法是确定性能提升的唯一准确的方法。

This parameter is used to determine which input points to add to the surface model as vertices.Specifying a value of 0 turns off vertex filtering.

Tip:A larger value will speed up surface model construction.The larger the value, the more input points will be filtered out.For input files with millions – or even billions – of points, it becomes essential to increase this value.

When a positive value for surface tolerance is specified, it works as follows.For each vertex that is being added to the model:

• If the x,y location is outside the 2D convex hull of the existing surface model, it is added to the model.
• If the x,y location is inside the 2D convex hull of the existing surface model:
  • 从现有的表面模型的Z值和顶点的z值之间的差值被计算。
  • 这种差异是相对于表面模型公差。
  • 顶点仅添加到如果该差值大于容差表面更大的表面模型;否则，该顶点被丢弃。

This parameter is used for the output portsDEMPointsandDEMRasterwhen these output ports exist on the transformer.It is also used ifDrapeFeaturesare input to the model.

• 汽车: The transformer will calculate each output point automatically.The平面method is used if the output point is within a surface triangle in xy and the不变method is used otherwise.
• 平面: Barycentric interpolation is used to determine the z value for each output point.If an output point is outside the 2D convex hull of the surface model, the output z value will be set to NaN (Not a Number).
• 不变：每个输出点的z值被设置为在底层模型最接近顶点的z值。

This parameter specifies the name of an elevation attribute for the output ports等高线andDEMPoints, when these output ports exist on the transformer.

These parameters specify the x and y sampling intervals for the outputDEMPoints。