# Pre-Processing Examples

What follows are some examples of pre-processing and their results. Our
aim is not to compare results, but to show some possibilities when
basic operators are combined. Filters were implemented using **vconv3d**
which performed a 3D convolution with 5x5x5 average mask. Segmentation was
done by threshold, using **vthresh3d**. Interpolation was computed by
**vinter**.

## Interpolation - Filtering - Segmentation - Filtering

In this case was used linear between slice interpolation with gray method.
On each step of this pre-processing are showed three renderings, using
normal vectors estimated in voxel space (**vvsnorm**), image space
(**visnorm**) and object space (**vvsnorm**), respectively.

After interpolation:

_
_

After first filtering:

_
_

After last filtering:

_
_

The following images are the same showed above, with their normal vectors
filtered by 2D convolution using a 3x3x3 average mask.
After interpolation:

_
_

After first filtering:

_
_

After last filtering:

_
_

## Segmentation - Interpolation - Filtering

In this case was used linear between slice interpolation with euclidean
method and binary output.
After interpolation are showed two renderings, using
normal vectors estimated in image space and object space , respectively.
Voxel space estimation can not be done
because the scene is binary. After filtering, three renderings are
showed as before, that is, using normal vectors estimated in voxel space,
image space and object space.

After interpolation:

_______________________
_

After filtering:

_
_

The following images are the same showed above, with their normal vectors
filtered by 2D convolution using a 3x3x3 average mask.
After interpolation:

_______________________
_

After filtering:

_
_

## Segmentation - Filtering - Interpolation

In this case was used linear between slice interpolation with gray method.
After interpolation are showed three renderings using normal vectors estimated
in voxel space, image space and object space, respectively.

After interpolation:

_
_

The following images are the same showed above, with their normal vectors
filtered by 2D convolution using a 3x3x3 average mask.
After interpolation:

_
_