filters.smrf#
The Simple Morphological Filter (SMRF) classifies ground points based on the approach outlined in [Pingel et al., 2013].
Example #1#
The sample pipeline below uses the SMRF filter to segment ground and non-ground returns, using default options, and writing only the ground returns to the output file.
json = """
[
{
"bounds": "([-10425171.940, -10423171.940], [5164494.710, 5166494.710])",
"filename": "https://s3-us-west-2.amazonaws.com/usgs-lidar-public/IA_FullState/ept.json",
"type": "readers.ept"
},
{
"type":"filters.smrf"
},
{
"type":"filters.range",
"limits":"Classification[2:2]"
},
"output.laz"
]
"""
import pdal
pipeline = pdal.Pipeline(json)
count = pipeline.execute()
print(f"Output contains {count} points")
Output contains 1436362 points
Example #2#
A more complete example, specifying some options. These match the optimized parameters for Sample 1 given in Table 3 of [Pingel et al., 2013].
json = """
[
{
"bounds": "([-10425171.940, -10423171.940], [5164494.710, 5166494.710])",
"filename": "https://s3-us-west-2.amazonaws.com/usgs-lidar-public/IA_FullState/ept.json",
"type": "readers.ept"
},
{
"type":"filters.smrf",
"scalar":1.2,
"slope":0.2,
"threshold":0.45,
"window":16.0
},
{
"type":"filters.range",
"limits":"Classification[2:2]"
},
"output.laz"
]
"""
import pdal
pipeline = pdal.Pipeline(json)
count = pipeline.execute()
print(f"Output contains {count} points")
Output contains 1451706 points
Options#
- cell
Cell size. [Default: 1.0]
- classbits
Selectively ignore points marked as “synthetic”, “keypoint”, or “withheld”. [Default: empty string, use all points]
- 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]
- where
An expression that limits points passed to a filter. Points that don’t pass the expression skip the stage but are available to subsequent stages in a pipeline. [Default: no filtering]
- where_merge
A strategy for merging points skipped by a
where
option when running in standard mode. Iftrue
, the skipped points are added to the first point view returned by the skipped filter. Iffalse
, skipped points are placed in their own point view. Ifauto
, skipped points are merged into the returned point view provided that only one point view is returned and it has the same point count as it did when the filter was run. [Default:auto
]