cleder / czml

Read and write CZML in Python

Introduction

This is an open source python library to read and write CZML files for Cesium, the WebGL Earth modeling engine.

Requirements

• pygeoif: https://github.com/cleder/pygeoif
• pytz: https://pypi.python.org/pypi/pytz

Tests

To run the tests (in the czml directory):

> python setup.py test

czml is continually tested with Travis CI

Usage and Examples

Reading CZML

Reading a CZML file into a mutable document object can be done by initializing a CZML document and then reading the file's contents into the loads() method on the document, like so:

# Import the library
from czml import czml

# Read an existing CZML file
filename = 'example.czml'
with open(filename, 'r') as example:
    doc = czml.CZML()
    doc.loads(example.read())

Writing CZML

The general approach to writing CZML with this python library is to define a document object, define packets and append them to the document, and then write the document to a file using the write() method:

# Import the library
from czml import czml

# Initialize a document
doc = czml.CZML()

# Create and append the document packet
packet1 = czml.CZMLPacket(id='document',version='1.0')
doc.packets.append(packet1)

# Create and append a billboard packet
packet2 = czml.CZMLPacket(id='billboard')
bb = czml.Billboard(scale=0.7, show=True)
bb.image = 'http://localhost/img.png'
bb.color = {'rgba': [0, 255, 127, 55]}
packet2.billboard = bb
doc.packets.append(packet2)

# Write the CZML document to a file
filename = "example.czml"
doc.write(filename)

Supported CZML Components

The components in this library are developed to follow the CZML Content documentation. Supported components and subcomponents are listed in docs/COMPONENTS.md.