filters.smrf

Filter ground returns using the Simple Morphological Filter (SMRF) approach outlined in [Pingel2013].

Default Embedded Stage

This stage is enabled by default

Example #1

The sample pipeline below uses filters.smrf to segment ground and non-ground returns, using default options, and writing only the ground returns to the output file.

{
  "pipeline":[
    "input.las",
    {
      "type":"filters.smrf"
    },
    {
      "type":"filters.range",
      "limits":"Classification[2:2]"
    },
    "output.laz"
  ]
}

Example #2

A more complete example, specifying some options. These match the optimized parameters for Sample 1 given in Table 3 of [Pingel2013].

{
  "pipeline":[
    "input.las",
    {
      "type":"filters.smrf",
      "scalar":1.2,
      "slope":0.2,
      "threshold":0.45,
      "window":16.0
    },
    {
      "type":"filters.range",
      "limits":"Classification[2:2]"
    }
    "output.laz"
  ]
}

Options

cell
Cell size. [Default: 1.0]
cut
Cut net size (cut=0 skips the net cutting step). [Default: 0.0]
dir
Optional output directory for debugging intermediate rasters.
ignore
A range of values of a dimension to ignore.
returns
Return types to include in output. Valid values are “first”, “last”, “intermediate” and “only”. [Default: “last, only”]
scalar
Elevation scalar. [Default: 1.25]
slope
Slope (rise over run). [Default: 0.15]
threshold
Elevation threshold. [Default: 0.5]
window
Max window size. [Default: 18.0]