Monocle Prime Measurement Analysis
Steampunk Digital, Co. Ltd.
2021-09-27
Steampunk Digital used a bookshelf for capture reference. In the testing we wanted tocheck for accuracy, precision, internal consistency, and ease of capture.

Figure 1 - Actual

Figure 2 - Monocle Prime
iPhone 12 Pro Max

Figure 3 - Reality CaptureSony a7R III, 20mm lensFigures
1. Actual – Ground Truth with tape measurement
2. Monocle Prime – Captured with an iPhone 12 Pro Max
3. Reality Capture Photogrammetry – Captured with Sony a7R III, with 20mm primelens

Accuracy
Extremely accurate: less than 0.5% error from actual. Monocle Prime, using an iPhone 12 Pro Max, is consistent
with Reality Capture photogrammetry using high-end DSLR Sony Camera and prime 20mm lens.

Figure 4 - Monocle Prime Measures

Left-side Height
Actual: 0.750m
Monocle Prime: 0.754m (0.5% error)
Reality Capture: 0.749m (0.1% error)

Bottom Width
Actual: 0.902m

Figure 5 - Reality Capture Measures

Monocle Prime: 0.903m (0.1% error)
Reality Capture: 0.898m (0.4% error)

Precision
Extremely precise: less than 0.01% variability across the capture volume.
This is close to limit of 32bit floating point precision.

Internal Consistency
Monocle Prime produces extremely internally consistent measurements. Processing
performed better at finding geometric surfaces of textured surfaces and edges even in dark
environments with moderate to high noise. Reality Capture was unable to produce somesurfaces of the book shelf (holes), and the model had poorer internal consistency due to aslight twist to the geometry.
However, the wall is a flat white surface, so both Monocle Prime and Reality Capture
showed high variability in both cases.
Using CloudCompare to process an iterative closest point alignment, it calculated an RMS
error of 2.3% global alignment error across the Monocle Prime and Reality Capture models.
This is consistent with the accumulation of error of both model processing methods, andaccounting for missing shelf geometry in the Reality Capture model.

Figure 6 - Cloud Compare - RMS after ICP Alignment

Ease of Capture
Monocle Prime works directly out of pocket, no floor level calibration, nor scale bars areneeded.

Whereas Reality Capture photogrammetry requires a DSLR (such as Sony a7R III) with ahigh-quality lens (such as the Sony 20mm f1.8 prime lens), and PC with Nvidia GPU forprocessing. Reality Capture also requires considerable time to learn how to use correctly,
including how to configure the camera for shooting photogrammetry, create markers,
create a ground plane control file, and steps to align and process the 3D geometry. All
necessary to get level and scale accurate results.

Figure 7 - iPhone 12 Pro Max

Figure 8 - Sony a7R III, 20mm Lens, with Scale BarConclusion
Monocle Prime aims to be the best option to get scale accurate 3D reference models,without requiring specialized equipment, preparation, or technical knowledge. The
prerequisite is an iPhone with two or more rear cameras, good light, and target object withsurface detail. The result is a photorealistic 3D model with less than 1% error dimensional
accuracy.

iPhones With Two or More Rear Cameras
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iPhone 13 Pro Max (2021)
iPhone 13 Pro (2021)
iPhone 13 Mini (2021)
iPhone 13 (2021)
iPhone 12 Pro Max (2020)
iPhone 12 Pro (2020)
iPhone 12 Mini (2020)
iPhone 12 (2020)
iPhone 11 Pro Max (2019)
iPhone 11 Pro (2019)
iPhone 11 (2019)
iPhone XS Max (2018)
iPhone XS (2018)
iPhone X (2017)
iPhone 8 Plus (2017)
iPhone 7 Plus (2016)