# `make.polyhedron`

[`make.polyhedron`](#digger.make.polyhedron) will modify an initial topobathymetric surface by adding or subtractracting a polyhedron based on user-defined planes. The following is typical usage for [`make.polyhedron`](#digger.make.polyhedron).

1. Prepare a topography file as a geotif.
2. Prepare or obtain a polygon shapefile indicating where the polyhedron should be applied. Ensure that the geotif and shapefile have the same coordinate system.
3. Determine a list of dictionaries, each specifying a plane of the desired polyhedron.
4. Run [`make.polyhedron`](#digger.make.polyhedron) to modify the topobathymetry file. Inspect the output and adjust any input parameters as needed.
5. 4. Using these files, set up a D-Claw simulation to run and analyze. `digger` will not do this for you.

A code snippet that uses [`make.polyhedron`](#digger.make.polyhedron) may be found in the file `digger/examples/pre-run/black_lake/make_polyhedron_black_lake_example.py`. In this example, a polyhedron is removed from above Black Lake.

```{literalinclude} ../../../../../examples/pre-run/black_lake/make_polyhedron_black_lake_example.py
:language: python
```

After this code runs, it will produce geotif and [topotype3](https://www.clawpack.org/topo.html) files that specify the modified topobathymetry.

It will also create diagnostic figures.

The standard diagnostic figure from [`make.polyhedron`](#digger.make.polyhedron)

```{figure} ../../../../_static/from_examples/polyhedron.png
:alt: Example digger.make.polyhedron summary figure.

An example of the diagnostic output provided by digger.make.polyhedron.
```