Keep Articulate library character at a fixed point within 360 image navigation

Joanne's suggestion will give you the best appearance, but at the cost of overhead to develop the graphics and limitations of a static image. There is another alternative that I was toying around some time ago. I refined it a bit for this question, but it is still a little rough and has some quirks. However, it has some potential for uses beyond your request so I will share it here.

With a little manipulation, you can overlay alternative objects over the markers that would normally be placed onto the 360 images. The markers have the advantage that Storyline already does some dynamic processing to track their positions to the position of the 360 image. If we attach another object, it can also dynamically track the image.

Basic demo: https://360.articulate.com/review/content/e799f9e8-b0a8-472b-b0e8-30375bd2f4aa/review

This approach works best when

• The object you want to fix to the 360 image is near the center of the initial view
• The object to fix is squarish or roundish.

If the object starts too laterally, then the perspective is exaggerated when tracking, which is not ideal. If the object is significantly longer in one dimension, then the ends tend to noticeably 'float' away from the background. Tall objects, like characters, look pretty good while panning from side to side, but vertical panning exaggerates the issue. 

Aside from the characters you requested, this could be used to add other different types of tracking objects to the 360 image. State changes can also be used on the overlayed objects.

A limitation to this approach is that the 360 image markers allow minimal editing, and they cannot be directly removed from the display. They are actually incorporated into the canvas with the image itself. Removing them, if possible, would require quite a bit more investigation.

Perhaps the object positioning could be adjusted to better cover the markers with the objects.