My humble attempt to create unwrapped icosahedral maps from equirectangular images. Insipration taken from here. If you find this useful, please consider giving it a star ⭐

This code was developed using python 3.8, however it should run on anything that has >= python 3.6.

To install the requirements, one can simply run:

$ pip install -r requiremets.py

The base class that one can use is the IcosahedralSampler class. Sample usage:

from ico_sampler import IcosahedralSampler

eq_image = imread('./assets/0.png')
ico_sampler = IcosahedralSampler(resolution = 600)

# generate unwrapped maps (as presented above)
unwrapped_image = ico_sampler.unwrap(eq_image, face_offset=0)

# generate unwrapped maps and shift they faces are put into the final panorama
unwrapped_image = ico_sampler.unwrap(eq_image, face_offset=2)


# create the image of the triangular face
face_image = ico_sampler.get_face_image(face_no=0, eq_image=eq_image)

# sample face colors from an eq image
face_colors = ico_sampler.get_face_rgb(face_no=0, eq_image=eq_image)

One can run the provided sample notebook to see exactly how the code works. One can create shift the output image by specifying the face_offset when calling ico_sampler.unwrap():

This repository also contains a command line utility program that can convert an equirectangular image to an incosahedral projection map:

$ python unwrap.py --input=<path to input> \ 
                   --output=<path to output> \
                   --face_resolution=600 \ 
                   --face_offset=0

A list of TODOs that might be implemented in the future:

• add interpolation when sampling the colors (current method: nearest) - this can cause grainy images, but increasing the face resolution (>600px) should diminish this effect
• add a tutorial like notebook to go over spherical projections

During the creation of this repository I hhave found the following articles to be useful:

• http://www.paulbourke.net/panorama/icosahedral/
• https://www.songho.ca/opengl/gl_sphere.html
• https://en.wikipedia.org/wiki/Regular_icosahedron
• https://mathworld.wolfram.com/RegularIcosahedron.html