Methods and systems measure a vehicle body parameter; e.g., a wheel alignment parameter such as ride height. Embodiments include a system having a target attachable to a vehicle body, and an image sensor for viewing the target and capturing image data thereof. A processor processes the image data, determines an initial spatial position of the target based on the processed image data, compares the initial spatial position of the target with a reference position, and prompts a user to align the target to an adjusted spatial position when the initial spatial position differs from the reference position more than a threshold amount. The vehicle body parameter value is determined based on the target's adjusted spatial position. In certain embodiments, the adjusted spatial position differs from the reference position by a position error value, and the processor mathematically corrects the vehicle body parameter value based on the position error value.