# Low resolution when importing an STL segmentation

**URL:** <https://discourse.slicer.org/t/low-resolution-when-importing-an-stl-segmentation/37715>\
**Category:** Support\
**Tags:** segmentation, resample, slicing, reslicing, stl, segmentations, segment-editor\
**Created:** [August 5, 2024, 8:35pm UTC](https://discourse.slicer.org/t/low-resolution-when-importing-an-stl-segmentation/37715 "2024-08-05T20:35:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ludoludo](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ludoludo/32/77521_2.png) [@ludoludo](https://discourse.slicer.org/u/ludoludo)\
**Post date:** [August 5, 2024, 8:35pm UTC](https://discourse.slicer.org/t/low-resolution-when-importing-an-stl-segmentation/37715/1 "2024-08-05T20:35:53Z")

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Hey!

I have a Nifti volume with the following dimensions: 588 x 734 x 1095, with an isometric resolution of 0.033 mm.

I’ve got an STL (or OBJ) file that represents a segmentation I’ve already made.

I’d like to convert this segmentation into a binary map that I can edit at high resolution: image spacing ~ 0.01.

The problem is that when I import this file and convert it directly, I end up with a very pixelated mask even at this resolution.

I’ve tried different approaches as indicated on the forum:  
[https://slicer.readthedocs.io/en/latest/user\_guide/modules/segmenteditor.html#segmentation-is-not-accurate-enough](https://slicer.readthedocs.io/en/latest/user_guide/modules/segmenteditor.html#segmentation-is-not-accurate-enough)

> [@Segmentation resolution](https://discourse.slicer.org/t/segmentation-resolution/1394/):
>
> Hello Can I select the pixel resolution of my segmentation? is it the same as native image resolution? thanks

> [@How to increase the segmentation resolution?](https://discourse.slicer.org/t/how-to-increase-the-segmentation-resolution/22981):
>
> Hi everybody, How can I increase the resolution of the segmentation as the default one uses large size of voxels (cubes)? Is this called oversampling? how to do it without changing the volume as I need to calculate the volume afterwards? Thanks,

> [@Increasing segmentation resolution](https://discourse.slicer.org/t/increasing-segmentation-resolution/15939):
>
> Hello all, How can I increase the resolution of a current segmentation? The master volume has its own quality and we cannot increase it but I want a segmentation with higher quality. I tried to crop the master volume with the spacing scale of 0.5 and with both linear and B-spline interpolators. However, it seems not to be working. Is this the correct way of doing what I am looking for or there other ways too? Thanks in advance.

I tested several versions by increasing the dimensions of the STL/OBJ file, but it doesn’t change anything 😕

Here are a few images:

 ![Before import](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/1/916eaf29ac8327928a0cb89345023e940dd3d170.png)  
 ![After conversion](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/4/1/41b4877b48174ff27a3bc99fc9b5c71f41d50695.jpeg)

The idea is to have a high-resolution 3D segmentation mask that I can register on my microCT so that it matches perfectly.

Thanks for your help!

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<div class="post-metadata">

**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:** [August 5, 2024, 8:45pm UTC](https://discourse.slicer.org/t/low-resolution-when-importing-an-stl-segmentation/37715/2 "2024-08-05T20:45:02Z")

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See step-by-step instructions [here](https://slicer.readthedocs.io/en/latest/user_guide/modules/segmentations.html#import-an-existing-segmentation-from-model-surface-mesh-file).

Note that an image of 588 x 734 x 1095 at 0.033mm/pixel resampled to 0.01mm/pixel would result in a 12GB image. For processing a segmentation of this size it would be recommended to have about 100GB physical RAM for optimal performance.