# VTKHDF unstructured grid with transient topology fails to read

**URL:** https://discourse.paraview.org/t/vtkhdf-unstructured-grid-with-transient-topology-fails-to-read/13852
**Category:** ParaView Support
**Tags:** vtk
**Created:** [February 2, 2024, 11:54pm UTC](https://discourse.paraview.org/t/vtkhdf-unstructured-grid-with-transient-topology-fails-to-read/13852 "2024-02-02T23:54:09Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Juan\_Jose\_Casafranca](https://discourse.paraview.org/user_avatar/discourse.paraview.org/juan_jose_casafranca/32/3499_2.png) [@Juan\_Jose\_Casafranca](https://discourse.paraview.org/u/Juan_Jose_Casafranca)
#### Post date: [February 2, 2024, 11:54pm UTC](https://discourse.paraview.org/t/vtkhdf-unstructured-grid-with-transient-topology-fails-to-read/13852/1 "2024-02-02T23:54:09Z")

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I am trying to read a VTKHDF file which contains an UnstructuredGrid with transient data. The transient data is for the points, but also for the topology, different steps have different number of cells.

This is the output of `h5dump -H` on the file

```auto
HDF5 "lines.vtkhdf" {
GROUP "/" {
   GROUP "VTKHDF" {
      ATTRIBUTE "Type" {
         DATATYPE H5T_STRING {
            STRSIZE 16;
            STRPAD H5T_STR_NULLPAD;
            CSET H5T_CSET_ASCII;
            CTYPE H5T_C_S1;
         }
         DATASPACE SCALAR
      }
      ATTRIBUTE "Version" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 2 ) / ( 2 ) }
      }
      DATASET "Connectivity" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 22 ) / ( H5S_UNLIMITED ) }
      }
      DATASET "NumberOfCells" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
      }
      DATASET "NumberOfConnectivityIds" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
      }
      DATASET "NumberOfPoints" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
      }
      DATASET "Offsets" {
         DATATYPE H5T_STD_I32LE
         DATASPACE SIMPLE { ( 14 ) / ( H5S_UNLIMITED ) }
      }
      DATASET "Points" {
         DATATYPE H5T_IEEE_F32LE
         DATASPACE SIMPLE { ( 22, 3 ) / ( H5S_UNLIMITED, 3 ) }
      }
      GROUP "Steps" {
         ATTRIBUTE "NSteps" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SCALAR
         }
         DATASET "CellOffsets" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SIMPLE { ( 3, 1 ) / ( H5S_UNLIMITED, 1 ) }
         }
         DATASET "ConnectivityIdOffsets" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SIMPLE { ( 3, 1 ) / ( H5S_UNLIMITED, 1 ) }
         }
         DATASET "NumberOfParts" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
         }
         DATASET "PartOffsets" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
         }
         DATASET "PointOffsets" {
            DATATYPE H5T_STD_I32LE
            DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
         }
         DATASET "Values" {
            DATATYPE H5T_IEEE_F32LE
            DATASPACE SIMPLE { ( 3 ) / ( H5S_UNLIMITED ) }
         }
      }
      DATASET "Types" {
         DATATYPE H5T_STD_U8LE
         DATASPACE SIMPLE { ( 11 ) / ( H5S_UNLIMITED ) }
      }
   }
}
}

```

AFAIK, everything is correct

However, when I load this file in ParaView, the first step, which contains 3 lines, looks correct but the second step, which contains 4 lines, only renders 3. Spreadsheet view show nothing changes for the Cells.

This is the file  
[lines.vtkhdf](https://discourse.paraview.org/uploads/short-url/3h20z1B6fePlR2u81Bs9hGRhjyh.vtkhdf) (92.8 KB)

![image](https://discourse.paraview.org/uploads/default/original/2X/f/f826f1ff2859545066deb5a82e8410d1fb0810ac.png)

 ![image](https://discourse.paraview.org/uploads/default/original/2X/b/ba36612cf1e48e46e3d3301f0c49bc08a4b66984.png)

---

<div class="post-metadata">

### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 5, 2024, 8:21am UTC](https://discourse.paraview.org/t/vtkhdf-unstructured-grid-with-transient-topology-fails-to-read/13852/2 "2024-02-05T08:21:41Z")

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@Lucas_Givord @Louis_Gombert