Below is a MRI of the hip from a sagittal view. We get hotly about snow, not just skiing, but because the femur is covered by layers that hide its true shape and movements.
To attempt to understand its underlying shape and movements w/ video or leds on the outside of the hip, outside of shorts is simply not correct!
It doesn't take much to cover up what you can't see.
Note: The snow is making things hard to concern! You really don't know what is under the surface.
The hip is just like the above picture. You really can't take a pic from the outside moving or tracking w/ leds. You can't know what is under the depth of the outer layer covering it. That is why it is important to track the interface of the rider to the saddle.
The femur (Os femoris), the bone of the thigh, is the longest bone in the body, so it has a lot of weight. Its upper (proximal) end comprises a head, neck, greater trochanter and lesser trochanter and you never know what shape and size it is going to be. The head of the femur is hemi-spheroidal in shape, and has a smooth articular surface for articulation with the acetabulum of the hip bone. The medial aspect of the femoral head has a pit termed the 'fovea'. Attached to the fovea is the ligament of the head of femur (ligamentum teres). Passing infero-laterally and somewhat backwards from the head of femur to join the shaft is the neck of femur. Thus the femoral neck in most cases is anteverted in relation to the femoral shaft apart from subtending an angle with the shaft in the coronal plane, but not always. The surface of the femoral neck is characterized by many small vascular foramina, and by the presence of many grooves and ridges. Below the neck, and continuous with it, is the femoral shaft.
The junction between the neck and shaft of the femur displays on the anterior aspect an oblique and somewhat rough ridge, termed the 'intertrochanteric line', while the posterior aspect of the junction between the neck and shaft of the femur is marked by a prominent and smooth elevation called the 'intertrochanteric crest'.
With the many different shape and sizes, this area is very hard to locate and track. Only with our new science can we really see how you interact with a given saddle. It has made a big difference for those who have used it to learn.