# Fixed Point ray cast does not render properly 2 components

**URL:** https://discourse.vtk.org/t/fixed-point-ray-cast-does-not-render-properly-2-components/1581
**Category:** Support
**Created:** [August 14, 2019, 2:33pm UTC](https://discourse.vtk.org/t/fixed-point-ray-cast-does-not-render-properly-2-components/1581 "2019-08-14T14:33:38Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![P.TURLAIS](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/p/d26b3c/32.png) [@P.TURLAIS](https://discourse.vtk.org/u/P.TURLAIS)
#### Post date: [August 14, 2019, 2:33pm UTC](https://discourse.vtk.org/t/fixed-point-ray-cast-does-not-render-properly-2-components/1581/1 "2019-08-14T14:33:38Z")

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Hi,

I have some troubles with FixedPointVolumeRayCastMapper when using 2 components. I have created a simple test in Python.

The dataset is a set of planes convolved with a _sinc_ with 3 lobes along the **x** axis.

The transparency is set to be 0.0 below 0.1, 1.0 above. Only positive lobes are displayed.

With 1 component, the image is what I expect. With 2 components, the 2nd being the copy of the first, some planes are not rendered completely ??  
 ![im1](https://discourse.vtk.org/uploads/default/original/1X/b8b5e6b5c4a21f36e27c2a1acdd508060280578a.png) ![im2](https://discourse.vtk.org/uploads/default/original/1X/ca6c020a3929f3a8bc7fc83790f86fda7da1d121.png)

If I use the SmartVolumeMapper, I get what I expect with the 2 components.  
 ![im3](https://discourse.vtk.org/uploads/default/original/1X/0c8e83ca25a7ccfcae1b7dc3f5405c0a500bfb70.png)

Is there something wrong in the setup/parameters or limitations in fixed point ray cast ?

Thanks  
Pierre TURLAIS  
[tst\_plane.py](https://discourse.vtk.org/uploads/short-url/bpZH01diKjlFxb7NkALoTH4SNWJ.py) (3.9 KB)