I’ve been searching a way for long time to make peirce quincuncial panos under Linux.

Why? I discovered a textured 3d sphere on setchfab, available for download, mapped with a square image, rendering it like a 360 pano.

And this seems cool to limit the number of seams on the sphere , contrary to the equirectangular mapping (just check zenith and nadir ). But that was not so easy to find, especially under Linux : all related posts on the web are dated ( the most recent must have been writed in 2010…), due to the fact that it has been considered as an ugly type of projection, with great distorsions on the borders of the square, and couldn’t offer such quality as miniplanets ( for example ), when one wants to « play » with its 360 panos.

*A bit of history*:

First of all I’ll link there almost all I’ve found unitl today on this theme, as a memo:

definition and history: http://en.wikipedia.org/wiki/Peirce_quincuncial_projection

a study on the peirce quincuncail projection applied to panos: http://arxiv.org/pdf/1011.3189.pdf

a way to make it mathematically:

http://mathematica.stackexchange.com/questions/24257/peirces-quincuncial-projection

a flickr pool showing pierce quincuncial panos:

https://www.flickr.com/groups/quincuncial/pool/

Well, that seem a cool way to present a 360° pano, but this option doesn’t exist in Hugin , so I had to dig to find how they all have done it : some are using flexify ( a proprietary photoshop plugin ) , other are « geek »( or scientists) enough to make it the mathematical way with matlab, but I use GIMP , and I’m not a student and have no access to matlab; I also use Blender , I’ll see if I can make it with it.

#### The way with GIMP:

You’ll have to install mathmap : https://www.complang.tuwien.ac.at/schani/mathmap/

It’s a bit dated but still working on gimp 2.8 , when installed you’ll find the mathmap plugin in the » filters>generic » menu ; there you’ll get a stack of options to transform your images.

Here is the flickr discussion where I got all to make it work , with the working script to make a Peirce quincuncial pano:

https://www.flickr.com/groups/mathmap/discuss/72157604625488382/

Link to the mod (for early gimp ) :

https://www.flickr.com/groups/mathmap/discuss/72157622843632187/

I’ll let you search a bit, all the necessary docs are there.

Problem is when you want to visualize it as a 360° panorama on the web: I don’t know if krpano offer this option (in this case tell it to me ), but I didn’t found any opensource viewer offering it.

#### The way with Blender:

Let see a working and downloadable example I made there :