#!/usr/bin/env python
# coding: utf-8

# # Viewshed Analysis

# This notebook is a basic introduction to viewshed analysis in *GRASS GIS* in *Jupyter Notebook*. In addition to common *Python* packages, it demonstrates the usage of `grass.script`, the *Python* API for GRASS GIS, and `grass.jupyter`, an experimental *Jupyter Notebook* specific package that helps with the launch of *GRASS GIS* and with displaying maps.
# 
# This interactive notebook is available online thanks to the [https://mybinder.org](Binder) service. To run the select part (called a *cell*), hit `Shift + Enter`.

# ## Starting GRASS in Jupyter Notebooks

# In[ ]:


# Import Python standard library and IPython packages we need.
import os
import subprocess
import sys

# Ask GRASS GIS where its Python packages are.
sys.path.append(
    subprocess.check_output(["grass", "--config", "python_path"], text=True).strip()
)

# Import the GRASS GIS packages we need.
import grass.script as gs
import grass.jupyter as gj

# Start GRASS Session
session = gj.init("../../data/grassdata", "nc_basic_spm_grass7", "user1")

# Set computational region to elevation raster
gs.run_command("g.region", raster="elevation@PERMANENT", flags="pg")


# ## Viewshed analysis
# Compute viewshed from a new 32 story tower located in downtown Raleigh, NC.

# In[ ]:


gs.parse_command("g.region", raster="elevation", flags="apg")
gs.write_command("v.in.ascii", input="-", stdin="%s|%s" % (642212, 224767), output="viewpoints")
gs.run_command("r.viewshed", input="elevation", output="tower_los", coordinates="642212,224767", observer_elevation="165", max_distance="10000")


# Display result with basemap:

# In[ ]:


vs_map = gj.InteractiveMap()

vs_map.add_raster("tower_los", opacity=0.7)
vs_map.add_vector("viewpoints")
vs_map.add_layer_control()

vs_map.show()