Abstract: A method of detecting the 3D shape of human body and a system of providing Virtual Fitting Room (VFR) service to online retailers over the Internet, in which customer films her/his body moving in front of the camera in a body suit with visible markers. Film is uploaded to the VFR system and processed there by extracting markers coordinates, by tracking markers from frame to frame to achieve automatic registration, and by performing photogrammetric processing of the marker coordinates to obtain and store 3D shape of the customer body. Customer selects an apparel item on an online retailer website, online retailer computer sends a request for fitting service to the VFR system, VFR system retrieves and processes customer digitized 3D body shape and digitized representation of the apparel item, returns virtual images of the customer fitted in the item to online retailer for display of the images to customer.