The Paradox logo made in desmos (an online graphing. A great starting point is the Wikipedia article on vector graphics. It explains how primitive math objects like lines, circles, ellipses etc can have their plots arranged to form pictures. It's very handy for drawing figures/logos like this, and can even import images from.
Emblems - Domination categoryCreating your own emblems Emblems are simply squared images that the game sticks on top of a background to create a flag.For each emblem 3 texture files in the Direct Draw Texture format (.dds) are required: a default, medium-sized one; a big one, usually white and displayed only on the galactic map; and a small one displayed next to units.It is recommended to add the emblems using mods instead of placing them directly in the game folder to avoid any possible problems.