Add VoxelGridLarge - to handle larger point clouds / smaller leaf sizes

[MarkHedleyJones]

This pull request addresses #4365
It replaces the use of an int based voxel index variable with int64_t type.
As an example, this modification increaces the capacity of the filter (with a 3cm leaf size in each axis) from 38.7m³ to 62.9km³.

The change was made in a copy of the voxel_grid filter, called voxel_grid_large.
I did this to prevent negatively impacting any users of the original voxel_grid filter (for example, I don't know what the performance cost would be on embedded systems).

A summary of the performance of this change is:

• Presented processing times are averages taken from 50 executions (processed on an i7-4770 CPU)
• Leaf too small warning indicates whether or not the original/master voxel_grid filter produced an error alerting the user that the leaf size was too small.
• The original pcd file can be downloaded from sourceforge. It is Rf14.pcd within the kitchen.zip file.

[kunaltyagi]

Hi @MarkHedleyJones Thanks for the PR and the amazing writeup

PCL is going in a different direction to support large point clouds. We are using pcl::index_t and allowing the users to configure the library using PCL_INDEX_SIZE and PCL_INDEX_SIGNED.

As such, would it be possible for you to instead change the VoxelFilter itself to use index_t instead of int?

In the current state, this PR duplicates a lot of code and is hard to review. I would not be in favor of merging this.

[MarkHedleyJones]

Hi @kunaltyagi
Thanks for your review.
I think that method of supporting various index types make a lot of sense.
I'll look at reworking what I've done to fit that instead.

[MarkHedleyJones]

@kunaltyagi Hi. I've made some changes to the existing voxel_grid implementation in line with your suggestion of using PCL_INDEX_SIZE to set the relevant voxel_grid indicies, however I can't compile even the master branch when PCL_INDEX_SIZE = 64.
The errors are related to calls with unsupported types in kdtree
Are builds being tested against 64 bit indicies in CI?

[kunaltyagi]

No. That's a WIP. There are PRs to (#4350,#4407, #4408) add the feature slowly across PCL

Please make the changes in voxel grid, instead of in voxel_grid_large

[stale]

Marking this as stale due to 30 days of inactivity. Commenting or adding a new commit to the pull request will revert this.