When you use your smartphone screen for VR, it is split screen into left and right eye views. On many smart phones, the center on center distance between the left and right images nearly matches the width of your eyes (inter-ocular spacing). This inter-ocular spacing, on average, is about 2.5 inches (65 mm) horizontal.
|Tekla3D Free Viewing QR Code (www.tekla3d.com)|
Given a phone with this approximate screen dimension (5 to 6 inches), you can freeview 3D stereo side-by-side photos on you phone, similar in ways you would view Magic Eye stereogram puzzles. See my blog posting about free viewing.
With free viewing you do not need to use a VR headset!
I thought it you be helpful to have a QR code that can set your Google VR/Cardboard apps for free-viewing without a VR headset. Basically it tells the app there is very little lens distortion - you are not using a headset! I created the QR code above from the Google Cardboard Viewer Profile Generator.
I tried this setting on my phone with a few Cardboard apps and it works, or example, 3D/VR Reel HGI Fashion app. It may help to have reading glasses to see the phone screen up close. I used +2.0 magnification. I think it helps if the app does not require a lot of head movement. The experience is not a immersive as using a VR headset, but is better for 3D photos.
If you encounter eye strain or any discomfort, do not free view. Not everyone can do this.
Let me know if this works for you. Good luck!