Patent ID: 8923566

Claim:
A smart portable device for recognizing a current position of the smart portable device without using a Global Positioning System, the smart portable device comprising: at least a processing device, for receiving instructions to execute the following steps: determining a distance between the smart portable device and a target object according to a digital image of the target object; acquiring coordinate information of the target object from a geographic information system of a navigation software stored in the smart portable device; acquiring a direction from the smart portable device to the target object; and determining the current position of the smart portable device according to the distance between the smart portable device and the target object, the coordinate information and the direction from the smart portable device to the target object; wherein the step of determining the distance between the smart portable device and the target object according to the digital image of the target object comprises: acquiring the digital image of the target object by a photo sensor of an image acquisition unit of the smart portable device; automatically calculating a length of a side of the target object in the digital image; acquiring a predicted length of the side of the target object from user prediction; automatically determining a mil value of the length of the side in the digital image; and calculating the distance between the smart portable device and the target object according to a ratio of the predicted length to the mil value.