Obtaining precise measurement through photogrammetry requires that a camera be calibrated.
Simply put, calibration is an understanding how light behaves once it has passed through the focal point of a lens and arrives onto the sensor. Precise calibrations are unique not only to particular lens+camera body combinations but for each focal length.
Approximate calibrations can be made using target fields plotted onto large sheets of paper, as some software packages suggest. For professional results, a larger building sized field of calibration control points should be used. When this is done, photogrammetry can yield very precise results.
For example,the accuracy of 3D points measured on an object approximately 10 meters/30 feet in size when using a calibrated camera with a full size sensor is ≤ 3 mm – and even less if special targets are used.
That’s 0.0003%!
Smaller sensors yield results more in line with 0.0015%. This is still quite good for architectural work. If you want your camera to be calibrated so that your photographs can be used as the basis for photogrammetric analysis, you can send it to me and I can create a calibration file for specific lens+body combinations that will work with Elcovision™ software. Afterwards, you could send me your photographs and I could process them into 3D point clouds, rectified photographs or measured drawings. Contact me to discuss your options: 540 447 4405.
Or contact the maker of Elcovision™ software:
