Error in measurement of a posture evaluation system is related to the digitalization, camera resolution and distance in relation to the volunteer studied, among others. These errors are summed up during the process and many of them are not possible to be avoided; however, they must be known and quantified. OBJECTIVE: to quantify the error of the positions measured by SAPO (Software para avaliação postural) in different experimental situations. METHODS: 16 photos of a 1.40m tall articulated mannequin were taken at the anterior, posterior, right lateral and left lateral planes with 3.2 and 12.0 megapixels resolution cameras, at 3.0m and 5.0m from the model. To quantify the error, the differences between the measurements obtained by SAPO and the ones made directed on the mannequin were calculated. RESULTS: the mean values of the horizontal, vertical, angular and distance measurements are close to zero; however, some angles were larger for the left and right measurements. The 3.2 megapixel digital camera located 3 m away showed the lowest error. The digitalization position is not influenced by the experience of the evaluators. CONCLUSION: SAPO is an accurate method for clinical use. Further studies are necessary to verify the effect of the position plane of the volunteer in relation to the camera, the effect of the relocation and the measurement palpation provided by the software.
software; posture; evaluation
