# Display both 3D polydata and 2D "projected" images preserving the geometrical relations
**URL:** https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926
**Category:** Support
**Created:** [May 8, 2019, 2:09am UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926 "2019-05-08T02:09:53Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@sdobashi](https://discourse.vtk.org/u/sdobashi)
#### Post date: [May 8, 2019, 2:09am UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926/1 "2019-05-08T02:09:53Z")
Hello everyone,
I have one 3D poly-data and several related 2D images obtained by some projection from certain angles, like X-ray images.
(2D images are not constructed directly from the 3D poly-data but provided from the outside.)
I want to display both 3D and 2D images in the same render window interactively preserving the geometrical relations:
I attached an image to illustrate the desired situation.
Specifically, if a 2D image is to be obtained by some projection operation from the direction
v = [sin(t)cos(u), sin(t) sin(u), sin(t)],
the 2D image should be placed so that its normal vector is parallel to v.
Also, in the interaction, both 3D and 2D are expected to move consistently.
I could display both 3D poly data and the projected 2D image
if the projection direction is X-, Y-, or Z- direction by using vtkPolyDataMapper and vtkDataSetMapper.
However, I want to place several 2D projected images
with each normal vector being any given projection directions.
Is there a way to realize such a display style in VTK?
I appreciate any suggestion.
Thanks in advance.
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [May 8, 2019, 1:45pm UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926/2 "2019-05-08T13:45:18Z")
These all look very doable using VTK. Read the [VTK textbook](https://lorensen.github.io/VTKExamples/site/VTKBook/00Preface/) and check out [VTK examples](https://lorensen.github.io/VTKExamples/site/) to see exactly how you can set this up.
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### Author:  [@marcomusy](https://discourse.vtk.org/u/marcomusy)
#### Post date: [May 8, 2019, 6:04pm UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926/3 "2019-05-08T18:04:35Z")
…i have a very similar example in [vtkplotter](https://github.com/marcomusy/vtkplotter) if your happy to work with python:
```python
from vtkplotter import *
vp = Plotter(axes=3, bg='white')
vp.load(datadir+"bunny.obj").scale(3000).pos(300,-300,-10)
for i in range(18):
a = vp.load(datadir+"images/dog.jpg")
a.crop(bottom=0.2).alpha(0.5).rotateX(20*i) # crop 20%
vp.show()
```
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### Author:  [@sdobashi](https://discourse.vtk.org/u/sdobashi)
#### Post date: [May 8, 2019, 10:37pm UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926/4 "2019-05-08T22:37:15Z")
Thank you very much for your response.
I found the method vtkImageData::SetDirectionMatrix in the GitHub version (maybe not yet implemented in VTK 8.2).
This method was the key to achieve my aim.
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### Author:  [@sdobashi](https://discourse.vtk.org/u/sdobashi)
#### Post date: [May 8, 2019, 10:39pm UTC](https://discourse.vtk.org/t/display-both-3d-polydata-and-2d-projected-images-preserving-the-geometrical-relations/926/5 "2019-05-08T22:39:40Z")
Thank you very much for your help.
This is exactly what I wanted to, though I’m now developing in C++.
The vtkplotter seems very useful for prototyping and to provide working examples.
Many thanks!