To summarize, the guidelines to follow when taking photographs for measurement are:
• try to get the angles between the shots as close to right angles (90 degrees) as possible,
• take at least three photographs,
• try to get all important points on at least three photographs,
• try to get as much overlap between adjacent photographs as possible,
• try to get photographs from both above and below the object, if possible,
• take many photographs of the object but use only four at the start until you determine you need some others, and
• measure the distance between two visible and clearly delineated points.
You do not need to follow these guidelines strictly, but you should be aware of them. The closer you come to meeting these guidelines, the easier the measurement process will be and the more accurate the measurements.
See DSM Photo Requirements for more information on photography for DSM/SmartMatch projects.