# How to crop 3D image from a 2D free-hand ROI?
**URL:** https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468
**Category:** Support
**Created:** [January 21, 2020, 1:45pm UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468 "2020-01-21T13:45:02Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)
#### Post date: [January 21, 2020, 1:45pm UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/1 "2020-01-21T13:45:02Z")
When analysis 3D image data by rendering, some tissue is unconcerned and it would distrub the analysis. Thus, I want to crop the image by a free-hand ROI just like RadiAnt:
In the above picture, the green polygon is the ROI, and I want to crop the outside image. The result would be:
And we can focus on the intrested arteries.
If I have the vtkImageData and the 2D coordiante of ROI, how can I crop the image? Does anybody implement the similar function?
---
### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [January 21, 2020, 3:57pm UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/2 "2020-01-21T15:57:33Z")
This feature is implemented in 3D Slicer (Segment Editor / Scissors effect). You can use it as is, or use the [source code](https://github.com/Slicer/Slicer/blob/master/Modules/Loadable/Segmentations/EditorEffects/qSlicerSegmentEditorScissorsEffect.cxx) in your application, or customize Slicer to do exactly what you need.
---
### Author:  [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)
#### Post date: [January 27, 2020, 10:23am UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/3 "2020-01-27T10:23:21Z")
It is a little hard for me to retrive the correct pipeline to crop the image by 2D ROI. Could you please tell me briefly about the pipelien so that I can find the details from the source code.
---
### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [January 27, 2020, 7:26pm UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/4 "2020-01-27T19:26:49Z")
You may add a few breakpoints and step through the code using the debugger to see how it works exactly.
If you find this too complicated and you are implementing a medical imaging application then probably it would make more sense to create your application by customizing/extending Slicer. It has been developed exactly for this purpose for decades, and for tens of millions of dollars.
---
### Author:  [@Linfeng\_Song](https://discourse.vtk.org/u/Linfeng_Song)
#### Post date: [August 28, 2020, 2:50am UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/5 "2020-08-28T02:50:49Z")
Hello,have you implemented this feature yet
---
### Author:  [@yuxing55555](https://discourse.vtk.org/u/yuxing55555)
#### Post date: [August 28, 2020, 5:48am UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/6 "2020-08-28T05:48:46Z")
> **[VTK体切割动画](https://zhuanlan.zhihu.com/p/121444689)**
>
> 对体进行任性形状的切割 体切割原理：
---
### Author:  [@NeuZhangQiang](https://discourse.vtk.org/u/NeuZhangQiang)
#### Post date: [August 28, 2020, 5:58am UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468/7 "2020-08-28T05:58:33Z")
Is the code available?