Human

Contents

The Human component models a person: a pilot, a passenger or a ground crew member, sized from population statistics and posed joint by joint. Its shape comes from a statistical model of adult body scans, so a few numbers -- sex, stature, body mass index, age and sitting height -- give a complete, realistic body. A skeleton inside the body then bends it into any pose from standing to seated. The result is a closed triangle mesh with a mass, a volume and a design eye point, for checking fit, reach, visibility and mass properties.

The Gen, XForm and Mass tabs are the ones every component has; see Gen, XForm and Mass. A Human has no Sub tab.

Quick Start

A standing person

1. On the Anthropometric tab choose Gender, then set Length Unit and Mass Unit to the units of the model.
2. Set % Stature and % BMI, or type the Stature and Mass directly.
3. Leave the pose as it is: a new human stands.
4. Place it with the XForm tab. The origin is the waist joint, so set the location of the waist, not the feet.

A seated occupant

1. Choose Gender, then set Length Unit and Mass Unit to the units of the model.
2. Set the size, as for a standing person.
3. On the Pose tab choose Preset SITTING and click Set, then adjust the joints to fit the seat.
4. Place it with the XForm tab, by the waist joint (Figure 2). Attach a Super Cone Auxiliary to it to show the field of view (see Design Eye).

Units

Length Unit and Mass Unit say what units the human is built in. They are not display units: the body is built at its stature in the length unit, so a 1.76 m man is 1.76 model units tall with Length Unit M and 5.76 with Length Unit FT. Set them to the units the rest of the model uses. The default is FT and LBM.

Changing the length unit keeps the person the same size in the real world: the stature percentile stays, and the stature is restated in the new unit. Changing the mass unit restates the mass.

The XForm tab's Scale has no effect on a human; its size is set by the stature and the length unit alone.

Body Size

The body shape is the statistical model from Human Shapes (humanshape.org, by Prof. Matthew P. Reed of the University of Michigan Transportation Research Institute), used with permission [1]. Its inputs are stature, body mass index, sitting height ratio and age; every point of the body follows from them. Between them, the controls on the Anthropometric tab describe most of the variation among adults.

Stature and BMI

Stature and BMI each have a value and a percentile; set either and the other follows. The percentiles come from the United States NHANES survey of adults aged 20 and over, 2011-2014, separately for men and women [2]:

Switching Gender keeps the percentiles, so a 95th percentile man becomes a 95th percentile woman, and shorter. The limits on Stature are the 5th and 95th percentile of the chosen sex.

Mass, BMI and stature are tied together by

$$\mathrm{BMI} = \frac{m}{h^2}$$

with the mass $m$ in kilograms and the stature $h$ in meters. Setting Mass sets BMI; setting BMI or % BMI sets the mass. Changing the stature keeps the BMI and changes the mass, so a taller person of the same build is heavier.

Age and sitting height

Age and Sitting H / H change the shape without changing the stature. A larger sitting height ratio gives a longer trunk and shorter legs. Age changes the build, by an amount that depends on the BMI. Leave both at their defaults unless the person in question is known to differ.

Volume and density

Volume is the volume of the closed body as posed, in the length unit cubed. With Auto Density on, the human's density on the Mass tab is set to Mass / Volume, so the mass properties of the model carry the person's mass at the right place. Turn it off to set a density by hand.

Origin and Axes

The human faces $-X$, with $Z$ up and the person's right side toward $+Y$, the way a pilot sits in an aircraft whose nose points along $-X$ (Figure 1). The origin is the waist joint, and it stays there whatever the pose: the legs hang from it standing and fold in front of it seated (Figure 2). Place a seated occupant by the waist joint, not by the seat or the feet.

Figure 1. A new human, its origin at the waist joint, and its axes. The person faces $-X$; the right hand is toward $+Y$.

Figure 2. The default human standing, as it is made, and in the Sitting preset. The origin is the same point of the body in both.

Pose

The pose bends the body at the joints of its skeleton. The skin follows the bones smoothly, so a bent elbow or hip deforms the flesh around it rather than hinging a rigid part. The skin is bound to the skeleton by the Pinocchio automatic rigging method [3].

Presets

Preset and Set at the top of the Pose tab put the human into a standard pose. Set replaces every joint angle and turns R/L Sym on; choose the preset first and then adjust.

A new human stands, in the Standing preset.

Joint angles

Every angle is in degrees. The names are the anatomical ones: AB/AD is abduction (away from the body's centerline) and adduction, FE is flexion and extension, IE is internal and external rotation. Elbow is the angle between the upper arm and the forearm, zero for a straight arm; the other angles are zero in a natural standing posture. Figures 3-5 show positive angles on the larger joints.

The limb joints are on the Pose tab twice, under Right Side and Left Side (Parms ending in Rt and Lt). The left angles mean the same motions as the right: a positive Shoulder AB/AD raises either arm out to its own side. With R/L Sym on, the default, the left side copies the right and its controls are greyed; turn it off to pose the sides apart.

Back and Waist both bend the upper body forward; Back bends it higher, at the middle of the back, and Waist at the waist joint (Figure 3). In both the legs and the origin stay where they are.

Figure 3. Back, Waist and Nod at 30, seen from the person's left. The tint shows the part that moved, as it was standing.

Figure 4. Positive shoulder and elbow angles. Shoulder AB/AD is seen from in front of the person and moves the right arm; Shoulder FE and Elbow are seen from the left and move the left arm; Shoulder IE is seen from above and moves the right arm, its elbow at 90. The tint shows the arm as it was.

Shoulder IE is easiest to see with the elbow bent: internal rotation swings the forearm in across the body, as in Figure 4. With the arm hanging straight it only turns the arm about its own length. Likewise Forearm turns the palm down when the elbow is bent 90 degrees, and toward the back when the arm hangs; the palm faces the thigh at zero.

Figure 5. Positive hip and knee angles. Hip AB/AD is seen from in front of the person and moves the right leg; Hip FE and Knee are seen from the left and move the left leg.

The skeleton does not check for collisions, so a pose can put an arm through the body or a leg through the other; check a demanding pose by eye.

Design Eye

The human carries a design eye point between the eyes (Figure 1), which moves and turns with the head. Two things use it:

• A Super Cone Auxiliary component whose parent is a human is placed at the design eye and turned with the head, so it shows the field of view from the person's eyes.
• From Point Visibility in Geometry Analysis can take a human as its viewpoint, and looks from the design eye.

With symmetry, each copy of the human has its own design eye. An attached Super Cone follows the eye as the human is posed or resized.

The Human in Analyses

A human is a closed triangle mesh, the same in every analysis. CompGeom, Mass Properties, the slicing analyses, interference checks and the mesh exports all use it, and VSPAERO takes it as one component. Its mesh is fixed by the model: the Gen tab's tessellation controls do not apply.

It is not a surface, so it has no sub-surfaces, its degenerate geometry is empty, and it takes no part where a surface is needed: CFD Mesh, FEA Mesh, Fit Model, or as the boundary or direction of a projection. Symmetry and Flip on the XForm tab work as for any component; see Symmetry and Flip.

Scripting

A human has no functions of its own in the API: it is built and posed through its Parms, in the groups Anthropometric and Pose, with the names in the tables above. The Set button is not in the API; to pose a human as a preset, set the joint angles from the preset table. ShowSkelFlag in the Anthropometric group draws the skeleton with the feature lines, unposed in black and posed in blue; it has no control on the screen.

import openvsp as vsp

h = vsp.AddGeom( "HUMAN" )
vsp.SetParmVal( h, "LenUnit", "Anthropometric", vsp.LEN_M )
vsp.SetParmVal( h, "Stature_pct", "Anthropometric", 0.95 )

# Seated, as the Sitting preset
for name, val in ( ( "ElbowRt", 80 ), ( "ShoulderIERt", 45 ), ( "HipFERt", 80 ), ( "KneeRt", 80 ) ):
    vsp.SetParmVal( h, name, "Pose", val )

vsp.Update()

References

1. Reed, M. P., Human Shapes, University of Michigan Transportation Research Institute. http://humanshape.org/
2. Fryar, C. D., Gu, Q., Ogden, C. L. and Flegal, K. M., "Anthropometric Reference Data for Children and Adults: United States, 2011-2014," Vital and Health Statistics, Series 3, Number 39, National Center for Health Statistics, 2016. Tables 9 and 11 (stature) and 14 and 15 (body mass index).
3. Baran, I. and Popovic, J., "Automatic Rigging and Animation of 3D Characters," ACM Transactions on Graphics, Vol. 26, No. 3 (SIGGRAPH 2007), 2007. The Pinocchio library: https://github.com/elrond79/Pinocchio