Why is floor unleveled or why does patient seem to always lean to one side in all my photos?

Many people ask us why the floor appears to be unlevel or why does it appear that most people are tilted to one side, when they were “sure” that they leveled the device with the lines turning “Green” before they took the picture.  Unfortunately, they fail to realize that our app can not account for y-axis rotation (axial) of the device or the subject or the camera itself which is on the side of the device is offset and not perpendicular to the client during taking the photos.  To compound this, there is evidence that people do have a tendency to have a ribcage shift based on being right handed.  

So during the photos, you may be ‘square’ to patient/client, BUT you and your client are OBLIQUE to the wall, or your device is slightly oblique to the client, or offset to the client.  The further you diverge in height from the camera lens, when oblique, it will ‘project’ or ‘show’ as a lateral bending.  THUS the floor un-level or baseboards etc.  So as long as you are square to patient, this is simply cosmetic.  However, if you are NOT and you are Oblique to patient and backdrop, then you have poor clinical data.  Being malpositioned with the device relative to the client either axially rotated or translated out of center (neither which can be controlled by the accelerometer controlled heads up display) can be noted by a total lateral flexion of the client (or floor board) relative to true vertical or the shoulders appearing laterally flexed (as an axial rotation will also project one side higher then the other). These are all physics of light perspective and photography (and even applies when taking x-rays as well).

So during photos, have the staff concentrate on the surroundings and look at the client and not just the “Heads Up Display”/ The device needs to be square to patient, and the camera itself needs to be in center and perpendicular to the client.  There is NO WAY to control for this motion with the accelerometers as the account for tipping (lateral bending) of device and tipping forward or backwards of the device.

Below you will find review of this as well as how to level the photos during importing if they are offset.

Video Tutorial: https://youtu.be/CkEO-22AyKc

1. Why Proper Camera Alignment Matters

When taking posture photos with an iPad (or any device), the camera lens must be perpendicular to the patient (or client).

This sounds like common sense, but it is one of the most frequent mistakes made by busy staff members. When the camera is even slightly offset or rotated relative to the patient, the resulting photo creates optical illusions that make the posture appear distorted. The software (PostureScreen) will still apply its corrections correctly, but it cannot overcome the fundamental geometry of the photo itself.

Key Point: PostureScreen corrects for some alignment issues (such as lateral offset causing the image to rotate and level out), but it cannot fix distortions caused by the patient being off-center relative to the camera lens.

2. Optical Illusions Explained (Real-World Examples)

Dr. Joe uses simple demonstrations to illustrate why these issues occur:

• Train-track illusion: When you look down parallel train tracks, they appear to converge and touch in the distance. This is an optical effect caused by perspective.
• Hand rotation demonstration: Hold your hand in front of the camera and move it left or right (off-center). The hand appears to rotate or tilt, even though it is not actually moving. The farther off-center it is, the more pronounced the apparent tilt becomes.
• Device rotation effect: If the iPad itself is rotated slightly while the camera is offset, one side of the image will look higher and the other lower. This creates the illusion of lateral flexion or translation that does not actually exist.

These same principles apply to both 2D photography and X-rays. The human eye and the camera interpret perspective the same way.

3. Common Doctor Questions and Answers

Q: Why does the patient look like they are leaning or translating off to one side? A: The camera lens was not perfectly in line (perpendicular) with the patient. Even a small lateral offset causes the image to show more of one side of the body (e.g., more palm or back of the hand in the hand example). This makes the rib cage, shoulders, or pelvis appear shifted or laterally flexed when they are not.

The software will rotate the image to make the floor or reference lines level, but the patient-to-camera relationship remains distorted. The result is an exaggerated or “pronounced” translation that is an artifact of the photo, not the patient’s true posture.

Q: Why does the floor look off-level or slanted in the image? A: This is the most obvious visual clue that the camera was offset. When the background removal toggle is turned off (so you can see the actual room background), you will often notice:

• The floor line slants downward on one side.
• Wall or floor lines are not horizontal.
• The patient appears to stand on a slope.

This occurs because the device (iPad) may be held slightly rotated or the staff member was standing to one side of the patient. PostureScreen can correct the image rotation, but it cannot know the exact spatial relationship between the patient and the camera unless sensors were implanted in the patient (which, of course, they are not).

Q: Is this a bug in PostureScreen? A: No. PostureScreen is working exactly as designed. The software correctly levels the image and applies green reference lines based on the photo provided. The distortion comes from the photography itself, not the analysis algorithms.

4. Best Practices for Staff Taking Photos

To eliminate these optical distortions:

1. The camera lens (not just the center of the iPad screen) must be perpendicular to the patient.
2. The plane of the device should be parallel to the wall behind the patient.
3. The patient should be standing against a plain wall (or with the background removal feature used for verification).
4. The device is intentionally tilted forward ~15° (following on-screen guides) so the staff member does not have to kneel. This is normal and expected.
5. A tripod is optional and NOT required for clinical reliability.
6. Always verify by toggling background removal off in the image edit screen. If the floor or walls look slanted, retake the photo.

Quick mental checklist for staff:

• Walk perpendicular to the patient.
• Sight down the camera lens directly at the patient’s midline.
• Make sure the top of the device is level left-to-right.
• Double-check before pressing the shutter.

5. How to Verify or Correct an Existing Photo

• In the PostureScreen image edit screen, toggle the background removal feature off to see the real background.
• If distortion is visible, you can manually rotate the image slightly to compensate (see separate tutorial videos linked in the app or knowledge base).
• Best solution: Retake the photo with proper alignment.

6. Additional Notes from Dr. Joe

• These principles were emphasized during training under Dr. Don Harrison, DC, Phd, MSE
• The same rules apply to all photography and 2D X-ray analysis.
• Proper alignment improves reliability and validity of your posture assessments.

How to level photos during import if slightly offset and un-level. This does not fix your problem per say, but makes it appear less prominent to true vertical or horizontal.

Video tutorial: https://youtu.be/-bc77K5w6y0?si=nqEls_Q_91NXlzON