One of the topics of discussion at the recent Fine Gigapan Conference in November that Ron Schott and Callan Bentley was the 'dream' to layer images within a Gigapan interface that were taken under plain and polarized light. The current Gigapan interface doesn't allow for overlays or extensive annotation so I started working with Open Layers a few weeks ago for another project that requires extensive annotation. In the process, I found a simple way to address the dream for flipping back and forth between plain and polarized light.
This is just part 1 of the progression, but in the example below all I've done is call two different images into the Open Layers API and with two lines of code you can add the layer switcher feature. Right now, the images are not gigapixel images (that's part 2) but you get the idea how seamless the transition can be, once the images load. I'm still working out the details for part 3, which will illustrate how to annotate your images so that they can be used as teaching tools for students (e.g. - you can label different minerals and link out to ancillary information like phase diagrams). Unfortunately, still haven't figured out how to do this with a 'rotating' stage. I'll post part 2 as soon as I finishing uploading the tiles. Until then, enjoy! I also haven't figured out why Blogger won't let me copy the code directly into this page, so the image below opens up in a new page: