paraview加载＜cell＞错误： the “offsets/types“ array is not long enough-卡核

错误说明

offsets array is not long enough

types array is not long enough

一个例子说明UnstructuredData的元素填充规则

vtk文件

保存vtk为vtu文件

简化vtu文件

错误说明

报错原因：<cell>元素填写不对

offsets array is not long enough

ERROR: In C:\\glr\\builds\\paraview\\paraview-ci\\build\\superbuild\\paraview\\src\\VTK\\IO\\XML\\vtkXMLUnstructuredDataReader.cxx, line 647
vtkXMLUnstructuredGridReader (000001FAC8C7BA40): Cannot read cell offsets from Cells in piece 0 because the "offsets" array is not long enough.

报错代码位于： int vtkXMLUnstructuredDataReader::ReadCellArray(vtkIdType numberOfCells,
vtkIdType vtkNotUsed(totalNumberOfCells), vtkXMLDataElement* eCells, vtkCellArray* outCells)中：

int vtkXMLUnstructuredDataReader::ReadCellArray(vtkIdType numberOfCells,
  vtkIdType vtkNotUsed(totalNumberOfCells), vtkXMLDataElement* eCells, vtkCellArray* outCells)

types array is not long enough

ERROR: In D:\\pv\\ParaView\\VTK\\IO\\XML\\vtkXMLUnstructuredGridReader.cxx, line 293
vtkXMLUnstructuredGridReader (000001EBA1A74270): Cannot read cell types from Cells in piece 0 because the "types" array is not long enough.

一个例子说明UnstructuredData的<cell>元素填充规则

《paraview数据文件格式PVD 和VTK数据文件格式》中对cell元素的说明如下：

文档中并没有说明<cell>中三个<DataArray>如何填充，尤其是offsets如何填充。

但是我们在ParaView – KitwarePublic发现paraview包含Generating data功能，可以把现有的vtk文件保存为vtu文件，从而得到规则。

vtk文件根据《paraview数据文件格式PVD 和VTK数据文件格式》中的例子三，自己设计。

vtk文件

下面以一个demo尝试去理解paraview中<CELL>三个<DataArray>填充规则：

test.vtk文件如下：

# vtk DataFile Version 2.0
Unstructured Grid Example
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 12 float
0 0 0  1 0 0  0 1 0  1 1 0  0 0 1  1 0 1
0 1 1  1 1 1  2 0 0  2 1 0  2 0 1  2 1 1

 
CELLS 2 18
8 0 1 2 3 4 5 6 7
8 1 8 3 9 5 10 7 11

 
CELL_TYPES 2
11
11

 
POINT_DATA 12
SCALARS scalars float 1
LOOKUP_TABLE default
0.0 1.0 2.0 3.0 4.0 5.0
6.0 7.0 8.0 9.0 10.0 11.0

paraview中显示test.vtk:

保存vtk为vtu文件

paraview 保存test.vtk为test.vtu文件：

【file】–》【save data]–》修改file of types为vtu,并且输入文件名称–》点击【ok】按钮后弹出，configure writer对话框，修改【Data Mode】为Ascii：

得到的test.vtu文件如下：

<VTKFile type="UnstructuredGrid" version="1.0" byte_order="LittleEndian" header_type="UInt64">
  <UnstructuredGrid>
    <Piece NumberOfPoints="12" NumberOfCells="2">
      <PointData Scalars="scalars">
        <DataArray type="Float32" Name="scalars" format="ascii" RangeMin="0" RangeMax="11">
          0 1 2 3 4 5
          6 7 8 9 10 11
        </DataArray>
      </PointData>
      <CellData>
      </CellData>
      <Points>
        <DataArray type="Float32" Name="Points" NumberOfComponents="3" format="ascii" RangeMin="0" RangeMax="2.449489742783178">
          0 0 0 1 0 0
          0 1 0 1 1 0
          0 0 1 1 0 1
          0 1 1 1 1 1
          2 0 0 2 1 0
          2 0 1 2 1 1
          <InformationKey name="L2_NORM_RANGE" location="vtkDataArray" length="2">
            <Value index="0">
              0
            </Value>
            <Value index="1">
              2.4494897428
            </Value>
          </InformationKey>
          <InformationKey name="L2_NORM_FINITE_RANGE" location="vtkDataArray" length="2">
            <Value index="0">
              0
            </Value>
            <Value index="1">
              2.4494897428
            </Value>
          </InformationKey>
        </DataArray>
      </Points>
      <Cells>
        <DataArray type="Int64" Name="connectivity" format="ascii" RangeMin="0" RangeMax="11">
          0 1 2 3 4 5
          6 7 1 8 3 9
          5 10 7 11
        </DataArray>
        <DataArray type="Int64" Name="offsets" format="ascii" RangeMin="8" RangeMax="16">
          8 16
        </DataArray>
        <DataArray type="UInt8" Name="types" format="ascii" RangeMin="11" RangeMax="11">
          11 11
        </DataArray>
      </Cells>
    </Piece>
  </UnstructuredGrid>
</VTKFile>

paraview打开test.vtu文件，显示效果跟test.vtk完全一样。

简化vtu文件

删除《paraview数据文件格式PVD 和VTK数据文件格式》没有介绍的一些字段和属性。

下面做一些实验：

删掉其中的<InformationKey>元素和删除<DataArray>中的RangeMin和RangeMax属性。得到1.vtu文件如下：

<VTKFile type="UnstructuredGrid" version="1.0" byte_order="LittleEndian" header_type="UInt64">
  <UnstructuredGrid>
    <Piece NumberOfPoints="12" NumberOfCells="2">
      <PointData Scalars="scalars">
        <DataArray type="Float32" Name="scalars" format="ascii" >
          0 1 2 3 4 5
          6 7 8 9 10 11
        </DataArray>
      </PointData>
      <CellData>
      </CellData>
      <Points>
        <DataArray type="Float32" Name="Points" NumberOfComponents="3" format="ascii" >
          0 0 0 1 0 0
          0 1 0 1 1 0
          0 0 1 1 0 1
          0 1 1 1 1 1
          2 0 0 2 1 0
          2 0 1 2 1 1          
        </DataArray>
      </Points>
      <Cells>
        <DataArray type="Int64" Name="connectivity" format="ascii" >
          0 1 2 3 4 5
          6 7 1 8 3 9
          5 10 7 11
        </DataArray>
        <DataArray type="Int64" Name="offsets" format="ascii">
          8 16
        </DataArray>
        <DataArray type="UInt8" Name="types" format="ascii" >
          11 11
        </DataArray>
      </Cells>
    </Piece>
  </UnstructuredGrid>
</VTKFile>

paraview显示效果同test.vtu和test.vtk.

下面再看看报错的vtk文件：

<?xml version="1.0"?>
<VTKFile version="0.1" type="UnstructuredGrid" byte_order="BigEndian">
	<UnstructuredGrid>
		<Piece NumberOfPoints="12" NumberOfCells="2">
			<PointData Scalars="Temperature">
				<DataArray Name="Temperature" type="Float32" format="ascii">0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0</DataArray>
			</PointData>
			<Points>
				<DataArray NumberOfComponents="3" format="ascii" type="Float32">0 0 0  1 0 0  0 1 0  1 1 0  0 0 1  1 0 1 0 1 1  1 1 1  2 0 0  2 1 0  2 0 1  2 1 1</DataArray>
			</Points>
			<Cells>
				<DataArray Name="connectivity" type="Int32" format="ascii">0 1 2 3 4 5 6 7</DataArray>
				<DataArray Name="offsets" type="Int32" format="ascii">0 0 </DataArray>
				<DataArray Name="types" type="UInt8" format="ascii">11</DataArray>
			</Cells>
			<Cells>
				<DataArray Name="connectivity" type="Int32" format="ascii">1 8 3 9 5 10 7 11</DataArray>
				<DataArray Name="offsets" type="Int32" format="ascii">0 0</DataArray>
				<DataArray Name="types" type="UInt8" format="ascii">11</DataArray>
			</Cells>			
		</Piece>
	</UnstructuredGrid>
</VTKFile>

理解正确的vtu文件就可以了，不要被误导

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