Book Image

Geospatial Development By Example with Python

By : Pablo Carreira
5 (1)
Book Image

Geospatial Development By Example with Python

5 (1)
By: Pablo Carreira

Overview of this book

From Python programming good practices to the advanced use of analysis packages, this book teaches you how to write applications that will perform complex geoprocessing tasks that can be replicated and reused. Much more than simple scripts, you will write functions to import data, create Python classes that represent your features, and learn how to combine and filter them. With pluggable mechanisms, you will learn how to visualize data and the results of analysis in beautiful maps that can be batch-generated and embedded into documents or web pages. Finally, you will learn how to consume and process an enormous amount of data very efficiently by using advanced tools and modern computers’ parallel processing capabilities.
Table of Contents (17 chapters)
Geospatial Development By Example with Python
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Blending images


We can make our results even more visually appealing and informative if we can combine the colorized image with the shaded relief image. Again, since we are dealing with arrays, we may deduce that this kind of composition can be achieved by performing an arithmetic operation between the two arrays.

In image processing, this is called alpha blending. Basically, a transparency is applied to both of the images and then they are blended into a new one. In the next steps, we are going to create a function that performs this operation:

  1. First, to avoid generating the shaded relief multiple times, let's save it on the disk and edit the if __name__ == '__main__': block of the raster_data.py file:

    if __name__ == '__main__':
        raster_data = RasterData('output/dem.tif')
        raster_data.adjust_values().create_hillshade(
            10, 60).write_image('output/shaded.png')
  2. Run the code and check whether the image was correctly written on the disk.

  3. Now, add the alpha_blend method to the RasterData...