# Empty position in Rectlinear \_grid dataset

**URL:** https://discourse.vtk.org/t/empty-position-in-rectlinear-grid-dataset/1512
**Category:** Support
**Created:** [August 7, 2019, 8:28pm UTC](https://discourse.vtk.org/t/empty-position-in-rectlinear-grid-dataset/1512 "2019-08-07T20:28:20Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Jiaxiang\_Wang](https://discourse.vtk.org/user_avatar/discourse.vtk.org/jiaxiang_wang/32/732_2.png) [@Jiaxiang\_Wang](https://discourse.vtk.org/u/Jiaxiang_Wang)
#### Post date: [August 7, 2019, 8:28pm UTC](https://discourse.vtk.org/t/empty-position-in-rectlinear-grid-dataset/1512/1 "2019-08-07T20:28:20Z")

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Hi,

For a rectlinear grid data set vtk file, it give the range of x,y,z coordinate. Then for each position, it will give a voxel (a number).

 ![image](https://discourse.vtk.org/uploads/default/original/1X/5af6094d0bb67997dc87ebd924b4cef0a86020a7.png) Is there a way to declare that position doesn’t contain any voxel. For example, i want to represent this geometry ![a](https://discourse.vtk.org/uploads/default/original/1X/71bc2dee86a8a25411680f5e85dd385e2b3b16af.png) . For the coordinate system, i have to specify x from zero to end. But the (0,0,0) doesn’t contain anything. Is there a featureID represent this point doesn’t contain any voxel.

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<div class="post-metadata">

### Author: ![lassoan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/lassoan/32/50_2.png) [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [August 11, 2019, 4:16am UTC](https://discourse.vtk.org/t/empty-position-in-rectlinear-grid-dataset/1512/2 "2019-08-11T04:16:38Z")

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If spacing is uniform along each axis then probably it makes more sense to store data in an image. You can make voxels transparent at positions where you don’t want to show anything.