Determining measurements contained within photo

[stevew40884386]

Hello, I took a photo of my living room with my daughter standing in the background. I calibrated the image by determining the # of pixels for the height of a gun case in the same image, then entered that number and switched the scale back to inches to see if I could get the height of my daughter. Her height was measured in the photograph 4 inches taller than she actually is. Can anyone offer any reasons why this would be?

[JJMack]

Was she the same distance from the camera as the guncase? If she was closer you would have more pixels per inch for her height then the gun case.

[stevew40884386]

No, she was 2-3 feet in front of it.

[stevew40884386]

Thanks, I appreciate your help. Just starting out.

[davescm]

As JJMack said , it sounds like perspective where closer objects appear bigger.

Try using the Measure tool within the vanishing point filter. You can set a grid to match the perspective then use the measure tool against that grid and it will compensate for the perspective. You can then calculate from there.

Dave

[stevew40884386]

Thanks. I appreciate it.