# filters.mongus¶

The mongus filter determines ground returns using the approach outlined in [Mongus2012].

Note

The mongus filter is deprecated and has been replaced by filters.pmf and filters.smrf.

The current implementation of this filter differs slightly from the original paper. We weren’t too happy with the criteria for how control points at the current level are compared against the TPS at the previous scale and were exploring some alternate metrics.

Some warts about the current implementation:

• It writes many intermediate/debugging outputs to the current directory while processing.
• We require the specification of a max level, whereas the original paper automatically determined an appropriate max level.

Default Embedded Stage

This stage is enabled by default

## Example¶

The sample pipeline below uses the filter to segment ground and non-ground returns, writing only the ground returns to the output file.

[
"input.las",
{
"type":"filters.mongus",
"extract":true
},
"output.laz"
]


## Options¶

cell
Cell size. [Default: 1.0]
classify
Apply classification labels (i.e., ground = 2)? [Default: true]
extract
Extract ground returns (non-ground returns are cropped)? [Default: false]
k
Standard deviation multiplier to be used when thresholding values. [Default: 3.0]
l
Maximum level in the hierarchical decomposition. [Default: 8]