[pdal] Status update for upcoming 1.0.0b1

[Howard Butler]

All,

I wanted to give you an update on PDAL developments of the past few months. I want to highlight the work that Andrew Bell and Brad Chambers have done to the codebase, point out new improvements and capabilities, and ask for some testing of our first upcoming beta release. 

Andrew Bell came on board to Hobu, Inc. in March and started by implementing support for a point cloud format called BPF. Through implementation of this driver, he kept a list of items that could be more generally altered to make PDAL easier in a number of ways. Since then, he has undertaken these tasks including:

* Refactoring (out) dynamic Schema and Dimension in exchange for a fixed set of dimension types
* Removal of Stage iterators (confusing and caused extra data copying)
* filters.merge now supports merging any data (union of inputs)
* Filters can create multiple outputs (tiling, chipper) 
* LAS 1.4 support

Brad Chambers of RadiantBlue has developed a number of exciting functionalities by connecting PDAL with PCL. These items include:

* Ground detection using Progressive Morphological Filters
* Voxel-based decimation
* PCD reader/writer
* PCL Visualization
* Outlier removal (multiple flavors)
* Pass-through filter (normal estimation, grid minimums)

And here's a list of other random improvements over the past few months:

* HDF5-based IceBridge support
* SBET reader/writer
* Greyhound http://github.com/hobu/greyhound reader
* SQLite reader/writer
* Points2grid now supports any GDAL-writeable raster
* `pdal delta` command for doing distance comparisons between two data sources
* Options are now set on stages explicitly, through setOptions, rather than at stage construction

PDAL apps, available via the `pdal` command, have also been beefed up. See http://www.pdal.io/apps.html for a listing of the functionality available through that mechanism. As before, all of the functionality is available via pipeline directives, but a lot of the basic, want-it-most-of-the-time capabilities are right at your fingertips.

As you can see, lots of effort has been going on, if a bit quietly. We've been trying to get done with all of the changes that would affect external API and case people's code to break. After we have a 1.0 release, we will be working very hard to minimize API-change-based breakage. Up until that point, we want to break things in any way that makes the API simpler, easier to implement, or faster -- and we've made changes recently that achieve all three.

Expect an announcement soon regarding the beta release, but master is in pretty good shape with regard to all of these items. We expect to have an OSGeo4W64 build available as part of the beta including all of the PCL goodies (thanks Brad) in addition to OSGeo4Mac recipes on that platform.  

Howard