The position of a waist or a hemline can still visually change your shape and shorten your legs. With all of the possible lengths and combinations body shapes and sizes you get billions of body variations that need to be dressed differently.
Human Body Ratios Scientific American
Vertical body measurement. Neck round measure around the base of the neck slightly loose. Always with a relaxed chest and arms down at side. Measure chest horizontally around body over nipples and parallel to the floor. Measure from the highest point on base of side neck to bust point nipple position. The vertical measurement is taken from the top of the body figure to its base. 3 shoulder to shoulder length.
Although a balanced vertical body shape when the 2 halves are roughly equal is theoretically ideal you still need to choose carefully. Suggestion use a pencil aligned vertically with back of the ear lobe pointing down to neck base to locate the highest point. Donot take this too tight. Short legged your upper torso will be longer than your lower body top of head to hips measurement will be. Then the horizontal measurements. Long waisted your waist is below the halfway mark between your bust line and your hips.
The length of your legs compared to your upper body your waistline your head size and neck length all factor into vertical proportion. Short waisted your waist is above the halfway mark between your bust line and your hips. Vertical proportions are the relation of your body parts to each other and as a whole. Long body short legs. Measurement is taken around the arm. It is in this order for the vertical measurements i assume 1 body length.