Simultaneous localization and mapping (SLAM) devices with scale determination and methods of operating the same

A method for determining the scale of a digital 3D model may include receiving, corresponding to a plurality of images, a respective plurality of first distances between the camera and the object in the environment and calculating, using a simultaneous localization and mapping (SLAM) algorithm, a plurality of second distances between the camera and the object in the 3D model of the environment. The method may include calculating a plurality of ratios corresponding to the plurality of images based on respective ones of the plurality of first distances and respective ones of the second distances and determining a scale of the 3D model based on the plurality of ratios. The method may include creating a scaled digital 3D model based on the 3 D model and the determined scale of the 3 D model. Distances and sizes in the scaled 3D model may correspond to actual distances and sizes of the environment.