The most common problem with before-and-after comparison is not a lack of images, but that the two images were not taken under the same conditions at all. Standardize the basis first, then discuss change.
1. Photographs: intuitive, but too many variables
The strengths of photographs are that they are real, easy to read and easy to share. The problem is that lighting, angle, focal length, beauty filters and shooting distance all change the result. The same person can show a different contour under a different lamp.
Photographs work as an aid to communication, not as a measurement tool on their own. If they are used for comparison, at least fix the shooting position, light source and lens, and turn off beauty modes and filters.
2. 2D imaging: good for proportions, poor for depth
With a fixed scale, a 2D image can measure planar distances and angles, but it cannot directly reflect depth, volume or curvature change. Questions such as nasal dorsum height or midface volume are hard to explain from a flat image.
Lens distortion also deforms the edges of the frame. When 2D images are used for before-and-after comparison, shooting distance and lens must be identical; otherwise the difference may come from the lens rather than the patient.
3. 3D scanning: turning change into numbers that can be reviewed
A 3D model can measure volume, area and height difference; a color map shows the overall distribution of difference, a cross-section shows change at one level, and the multi-view mode places several time points on one screen (up to 8 models).
The value of these results is that they can be reviewed: another person can follow the same landmarks and conventions and reach a similar conclusion. They are not a conclusion about outcomes, and they do not replace the doctor's judgement.
4. Standardization checklist
| Condition | Requirement | What happens if it varies |
|---|---|---|
| Device and software | Same device and same version where possible | Differences in model scale and algorithm are misread as change |
| Working distance and posture | Same position, natural head posture | Contour and proportions shift |
| Expression | Neutral expression, relaxed bite | Soft-tissue deformation affects volume and height |
| Lighting | Fixed light source, avoid strong backlight | Texture and color comparison are distorted |
| Makeup and hair | Bare face or consistent makeup, hair pulled back | Skin tone and contour differences are misjudged |
| Time point | Record the date and recovery stage | Recovery-phase change is taken as the final result |
5. How the three media work together
Photographs provide intuition, 2D provides quick review, and 3D provides measurement and verification. Photographs are easier to read for external presentation; 3D is more reliable for internal discussion and follow-up records. Do not mix the three in one comparison, and do not use a retouched photograph to explain 3D metrics.
6. Conclusions that images cannot support on their own
- A change in the image does not equal a treatment result; individual differences and recovery stage both affect the outcome.
- A single comparison cannot predict long-term stability.
- 3D measurements need to be combined with clinical judgement and cannot serve as a basis for diagnosis on their own.
- Authorization should be obtained and identifying features removed before any external display.
Related pages: 3D digital plastic surgery system, MVS-P6, MVS-800, Procurement and service FAQ.
This article describes product functions and processes and does not constitute medical advice; specific configurations, specifications and deliverables are subject to the product version and the contract.