Supervoxel example updates

[jpapon]

Added better messages to explain single camera transform, fixed bug where negative Z values were always abs'd, even if transform disabled.
Added ability to use normals provided within point cloud, and ability to disable this.
Adjusted visualization so voxels and supervoxels are displayed better.
Cleaned up command line parsing.

[taketwo]

Maybe we should throw out z == 0 as well?

[jpapon]

I thought about it, but didn't include it because of those files we encountered a while back where people were putting points at (0,0,0) instead of nan. log(z) "converts" those points to nans =)

[taketwo]

I also remembered those files! But you are right, log(z) does the right thing for them.

[taketwo]

On a separate note, what do you think about removing getColoredCloud() from supervoxel segmentation once #849 is merged?

[jpapon]

On a separate note, what do you think about removing getColoredCloud() from supervoxel segmentation once #849 is merged?

We definitely should, we can remove the same from LCCP segmentation as well, but I think there's one piece missing before we can. We either need a savePNGFile overload for PointXYZL that lets you colorize the output, or better yet, a general colorize function that creates a new cloud with the RGB field added.

[taketwo]

We either need a savePNGFile overload for PointXYZL that lets you colorize the output

This is already available, though it uses COLORS_MONO. I will augment #849 to make COLORS_GLASBEY the default value, which makes more sense.

better yet, a general colorize function that creates a new cloud with the RGB field added.

Maybe. Any suggestions on the signature, name, and location of such a function?

[jpapon]

This is already available, though it uses COLORS_MONO.

Oh, I didn't see that. savePNGFile has different behavior for labeled points though, it saves them as 16-bit single channel images.

Maybe. Any suggestions on the signature, name, and location of such a function?

It's not really needed if there's already a write PNG function.

[taketwo]

it saves them as 16-bit single channel images

Yep, this I will change.

[jpapon]

Yep, this I will change.

Just to be sure - we need to keep both available. Saving the label as a single channel is useful for benchmarking.

[taketwo]

Unfortunately with the current interface only one option can be conveniently exposed through savePNGFile(file, cloud, field) function.

But other options are still accessible, though you'll need to write some code, e.g.:

PointCloudImageExtractorFromLabelField<PointT> pcie (COLOR_MONO);
pcl::PCLImage image;
pcie.extract (cloud, image);
savePNGFile (file_name, image);

So which one should be the default you think? Mono or colorful?

[jpapon]

Oh, I didn't even see that new interface. I think Mono makes the most sense logically, but I'm split. Maybe put a note in the doxygen comments with the code snippet showing how to colorize labels?

[taketwo]

Agreed, makes sense to increase awareness of the various "extractors" that are now available.