The article discusses the reasons for the inaccurate determination of the position and the linear dimensions of objects using a stereoscopic pair meters and methods associated with the construction of the geometric model. The process of measuring the spatial position and size of the object is divided into two stages: the display image of the object and its valuation. We derive a new relationship linking the lag of an object with a surface area of the pair meter without the use of transcendental functions, which are the main cause of errors when performing stereo measurements. Get the right size of the object transformation mappings pair meter, which is expressed by the coefficient of general relevance for each observation point on the object. The concepts of reliability and uncertainties display linear dimensions of the object. Getting the right pair of transformation mappings meter explains the physical causes range depending on the size of the received information the pair meter.