About MultiSliceImageMapper

I want to render a obj file in center of MultiSliceImageMapper, please tell me how to do? I have tried to set obj file’s actor position by using the data of the vti file’s data, but it is not satisfied

// The vti file's center
 const data = vtiReader.getOutputData()
 this.vtiFileCenter = data.getCenter()

// set obj actor position
const nbOutputs = objReader.getNumberOfOutputPorts()
for (let idx = 0; idx < nbOutputs; idx++) {
       const source = objReader.getOutputData(idx)
       const mapper = vtkMapper.newInstance()
       const actor = vtkActor.newInstance()
       item.actor = actor
       const color = vtkMath.hex2float(item.colorVal)

It looks like you are trying to align a vessel segmentation with a volume. Was the segmentation taken from the VTI, or an image format that contains position/orientation info (e.g. NRRD)? I ask because I am not sure how your segmentation relates to your image, transformation-wise.