1. An electronic-device-implemented method for calculating a geometric scale of an object, comprising: accessing two or more images of the object, wherein the two or more images are associated with different perspectives of the object in an environment, and wherein a given image has an associated imaging-device characteristic; calculating the geometric scale of the object based on the two or more images, the different perspectives, and the imaging-device characteristics associated with the two or more images; scaling an image of the object based on the calculated geometric scale; and providing a combined image, wherein the combined image is generated by combining the scaled image of the object with another image.