# raycasting initially renders at low resolution

**URL:** https://discourse.vtk.org/t/raycasting-initially-renders-at-low-resolution/582
**Category:** Support
**Created:** [March 21, 2019, 2:25pm UTC](https://discourse.vtk.org/t/raycasting-initially-renders-at-low-resolution/582 "2019-03-21T14:25:07Z")
**Posts on this page:** 1
**Showing post:** 3

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### Author: ![Marco](https://discourse.vtk.org/user_avatar/discourse.vtk.org/marco/32/1461_2.png) [@Marco](https://discourse.vtk.org/u/Marco)
#### Post date: [March 28, 2019, 12:17pm UTC](https://discourse.vtk.org/t/raycasting-initially-renders-at-low-resolution/582/3 "2019-03-28T12:17:56Z")

</div>

Hi.  
I have a very similar problem.  
I am using the latest VTK v8.2.0 from a Java application.  
I am rendering a volume through vtkFixedPointVolumeRayCastMapper.

Even if I set:

======  
// Initialize the mapper  
volumeMapper = new vtkFixedPointVolumeRayCastMapper();  
volumeMapper.AutoAdjustSampleDistancesOff();  
volumeMapper.LockSampleDistanceToInputSpacingOn();  
volumeMapper.SetBlendModeToComposite();  
volumeMapper.SetImageSampleDistance(1);  
volumeMapper.SetInteractiveSampleDistance(1);

```
  GetRenderWindow().SetDesiredUpdateRate(0.001);

```

======

the very first rendering of my volume appears very low resolution:

 ![CPUVolRend_LowResFirstRendering](https://discourse.vtk.org/uploads/default/original/1X/97d3ccd050048b5c26a80dab22bac612d2da6133.png)

Then, the first time I interact with the view (mouse drag to rotate the camera), then my rendering restores to high resolution, and remains hi-res from now on:

 ![CPUVolRend_HiResAfterInteraction](https://discourse.vtk.org/uploads/default/original/1X/14ab4b8535e4ecfc3eae91e8496583f43ba00ec0.png)

Can you guess why the very first rendering of my CPU volumer mapper is so low res? How to fix this?

Thanks in advance.  
Best regards,

Marco Sambin

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