Equirectangular Projection with Pannellum
This post will cover equirectangular projection using the Pannellum toolset. Details about Pannellum can be found here, https://pannellum.org/documentation/overview/. I have included two types of images as examples, cube and spherical. Both of them give a spatial sense to the observer viewing out from inside a box or ball. The example patterns represent a rudimentary reticle for measurement that can be applied to a physical environment.