What is lens height?
Lens height is the distance between your floor and the center of your lens.
When using a 360 camera, you can just measure that distance directly. But when using a DSLR or smartphone camera, you need to make sure your lens is at the nodal point (How to determine lens nodal point for panoramic photography) before taking your photos and measuring your lens height.
When making projects with Metareal Stage, you can input your lens height in your project settings, or individually per panorama.
What's the ideal measurement?
As long as the lens height is about eye level when you're standing (for most people that's anywhere between 5 to 6 feet), that should be good enough for your tour.
More important than having a specific lens height is that you maintain the same lens height throughout your shoot. Meaning you set your height at the start, and never change it until the end of your shoot.
Why is consistency important?
Lens height is the main measurement Metareal Stage uses to extrapolate all the dimensions of your project. So accurate lens height is essential if you want your panoramas to match up well, and keep your floorplan and tour measurements accurate.
And it's much easier to keep your lens height accurate if you never change it during your shoot. Then you can just input it in your project settings, instead of individually per panorama.