# ExtractVOI unable to slice in sagittal or coronal views

**URL:** https://discourse.vtk.org/t/extractvoi-unable-to-slice-in-sagittal-or-coronal-views/4896
**Category:** Support
**Created:** [December 26, 2020, 7:40pm UTC](https://discourse.vtk.org/t/extractvoi-unable-to-slice-in-sagittal-or-coronal-views/4896 "2020-12-26T19:40:47Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![charlessillett](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/c/b2d939/32.png) [@charlessillett](https://discourse.vtk.org/u/charlessillett)
#### Post date: [December 26, 2020, 7:40pm UTC](https://discourse.vtk.org/t/extractvoi-unable-to-slice-in-sagittal-or-coronal-views/4896/1 "2020-12-26T19:40:48Z")

</div>

Hi,

I am trying to use the vtkExtractVOI object with its method SetVOI to slice my 3D Nifti image in the axial, coronal and sagittal planes. Axial slicing works however sagittal and coronal slicings do not render any part of the image. I’m not too sure why… Any help would be much appreciated!

Here is an example of the code I’m using to extract a sagittal slice which fails to slice the image:

// Load NIFTI  
vtkSmartPointer reader = vtkSmartPointer::New();  
reader-\>SetFileName(filename1);  
reader-\>Update();

int extent[6];  
reader-\>GetDataExtent( extent );

int xSliceMin = extent[0];  
int xSliceMax = extent[1];  
int ySliceMin = extent[2];  
int ySliceMax = extent[3];  
int zSliceMin = extent[4];  
int zSliceMax = extent[5];

double xPlane = xSliceMax\*0.5;

vtkSmartPointer extractSlice = vtkSmartPointer::New();  
extractSlice-\>SetInputData(reader-\>GetOutput());  
extractSlice-\>SetVOI(xPlane, xPlane, ySliceMin, ySliceMax, zSliceMin, zSliceMax);  
extractSlice-\>ReleaseDataFlagOn();  
extractSlice-\>Update();  
vtkSmartPointer slice = extractSlice-\>GetOutput();  
vtkSmartPointer imgActor = vtkSmartPointer::New();  
imgActor-\>GetMapper()-\>SetInputData(slice);

vtkSmartPointer renderer = vtkSmartPointer::New();  
renderer-\>AddActor(imgActor);  
renderer-\>ResetCamera();