Frequently Asked Questions About Photogrammetry This section lists frequently asked questions about V-STARS, and photogrammetry. How accurate is V-STARS? How many photographs are needed for a measurement? How many points are needed for a measurement? Do I need scale for the measurement? How do I get it? How do I compensate for scale changes due to temperature? Can the object move while it is being measured? Do I need to use special targets with the system? Can I measure untargeted features? What size should the targets be? Can I use different size targets on the same measurement? How obliquely can I view the targets? Do I need to provide special lighting for the system? Do I have to consider the lighting where the measurement is being taken? Do I need to know where the camera is located when I take a photograph? How steady must the camera be when taking a picture? How far away do I have to get from the object to measure it? Where should I locate the camera to get a good measurement? How can I calibrate the camera and make sure the measurement is accurate?