It's a real valuable contribution to the AR world.

2022-01-07 Adding the third-person view and the accuracy controls. Instead of fixed values for measurement accuracy and mean point distance, the following formulas are used: - Measurement accuracy = base + increment * (object distance) - Mean point distance = increment * (object distance).

Once, the shape, size, position, orientation of an object surface is known, there are a variety of applications. YouTube CurvSurf, GitHub CurvSurf, FindSurface Web Demo.

The slope sign as shown in the previous answer is rendered based on: A gazing point on the object surface The surface normal at the gazing point The vertical (gravitational) direction.