# Resampling images - LinearInterpolateImageFunction

**URL:** https://discourse.itk.org/t/resampling-images-linearinterpolateimagefunction/4887
**Category:** Algorithms
**Tags:** interpolator, python
**Created:** [March 27, 2022, 7:55am UTC](https://discourse.itk.org/t/resampling-images-linearinterpolateimagefunction/4887 "2022-03-27T07:55:17Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![tabro](https://discourse.itk.org/letter_avatar_proxy/v4/letter/t/f0a364/32.png) [@tabro](https://discourse.itk.org/u/tabro)
#### Post date: [March 27, 2022, 7:55am UTC](https://discourse.itk.org/t/resampling-images-linearinterpolateimagefunction/4887/1 "2022-03-27T07:55:17Z")

</div>

Hi,  
I’m trying to resample a CT (nifti) of non-isotropic spacing to have isotropic spacing of (0.5, 0.5, 0.5), no rescaling. I’m using the code below. The output is an array of the desired size but consists of almost only zeros, except the first row of each slice.

```auto
def load_resampled_ct(input_file_name, spacing):

    input_image = itk.imread(input_file_name)
    inputspacing = itk.spacing(input_image)
    outputspacing = [spacing, spacing, spacing]
    output_origin = itk.origin(input_image)
    inputsize = itk.size(input_image)

    outsize = [int(inputsize[0] * inputspacing[0] / outputspacing[0]),
			    int(inputsize[1] * inputspacing[1] / outputspacing[1]),
			    int(inputsize[2] * inputspacing[2] / outputspacing[2])]

    interpolator = itk.LinearInterpolateImageFunction.New(input_image)
    Dimension = input_image.GetImageDimension()

    resample = itk.resample_image_filter(
        input_image,
        size=outsize,
        output_spacing=spacing,
        output_origin=output_origin
    )

    return itk.GetArrayFromImage(resample)

```

Can anyone see what is wrong here?

Best regards and thank you in advance!

---

<div class="post-metadata">

### Author: ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [March 28, 2022, 3:14pm UTC](https://discourse.itk.org/t/resampling-images-linearinterpolateimagefunction/4887/2 "2022-03-28T15:14:45Z")

</div>

You are forgetting to pass `direction`. It should be passed along analogously to spacing. If it is non-identity, that would explain problems.
