[pdal] writers.gdal: median

[Howard Butler]

> On Jan 28, 2022, at 6:23 PM, Jim Klassen <klassen.js at gmail.com> wrote:
> 
> Is there any interest in adding a median (and possibly Q1 and Q3) statistic to writers.gdal?

As long as the overhead associated with computing it is opt-in, I think this would a very useful addition. 

> I'm not sure this memory limitation would be easy to document clearly and I presume this is why median isn't already implemented. I certainly would not include it by default in the "all" mode.
> 
> There may be ways to make this more memory friendly if multiple passes through the point cloud would be allowed, but this is counter to how the existing writers.gdal stage is structured.

Related to earlier traffic, I think the distinction in behavior between "cell count" and "search window" count has some value for some applications. It would be nice to support both behaviors.