# 95% Hausdorff distance 0

**URL:** <https://discourse.slicer.org/t/95-hausdorff-distance-0/33928>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [January 23, 2024, 3:13pm UTC](https://discourse.slicer.org/t/95-hausdorff-distance-0/33928 "2024-01-23T15:13:03Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Young\_Wang](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/young_wang/32/13926_2.png) [@Young\_Wang](https://discourse.slicer.org/u/Young_Wang)\
**Post date:** [January 23, 2024, 3:13pm UTC](https://discourse.slicer.org/t/95-hausdorff-distance-0/33928/1 "2024-01-23T15:13:03Z")

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Hi there,

I’m working on an imaging fusion project that combines a small-FOV image with finer details and a large-FOV image with better description of surrounding anatomical structures.

To evaluate the performance ( reproducibility), I did the following:

1. Add two scalar volumes after a rigid transform of one volume while keeping one fixed to get a fused image(volume)
2. Intensity based segmentation A of the fused image(volume)
3. Repeat step 1-2 to get the second segmentation B.
4. Calculate the image metric with Hausdorff and DICE.

Here is the question. I noticed that both mean and maximum of Hausdorff distance values are reasonable but 95% is 0. I wonder if it’s something I am doing is not correct or that’s what I should expect? I came across a previous post mentioning the 95% could be 0.

Thank you for your time and help in advance.

 ![1000016459](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/7/b/7b217fea8de8bbdda6b999becf3d1727c52b13a8.png)  
 ![1000016458](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/a/5/a5bc76ba8f4d9e64211a7dc490d191dea73061c5.jpeg)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 23, 2024, 11:05pm UTC](https://discourse.slicer.org/t/95-hausdorff-distance-0/33928/2 "2024-01-23T23:05:07Z")

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If HD 95% is 0 then it means that 95% or more surface points have 0.0mm (or less than one voxel) error. This is possible if you use synthetic data and the alignment is nearly perfect.

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**Author:** ![Young\_Wang](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/young_wang/32/13926_2.png) [@Young\_Wang](https://discourse.slicer.org/u/Young_Wang)\
**Post date:** [January 25, 2024, 11:00am UTC](https://discourse.slicer.org/t/95-hausdorff-distance-0/33928/3 "2024-01-25T11:00:08Z")

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@lassoan Thank you for the reply!