The application or employment of a process or feature by which an artist will ensure both the ratio AND perspective of an image remain relative to that of the original image. Failure to "constrain proportions" has resulted in many innocent men being "duped" on internet dating sites (and the like), sustaining an eternal loss of essential "crop points."
TA:"I'm tryin to photoshop that sikk pic you got of me killin' a keg stand at the Rutgers party, Nig." "Everytime I resample, I end up lookin like Nicole Richie doin' a headstand on a Heineken keg can."
In classical mechanics, particularly Lagrangian Mechanics, a holonomic constraint is a special type of constraint of motion. It restricts the trajectory of a system of particles to a smooth manifold Q by the set smooth equations
a({x},t)=0
b({x},t)=0
.
.
.
Where
t=time
{x}= the set of 3N Cartesian coordinates for the system of N particles.
For N particles, the number of holonomic constraints must be less than 3N using the assumption that each equation has an explicit dependence to AT LEAST one coordinate.
A rigid body, defined by the constraint equations (using LaTeX) is
\left| {x_i - x_j } \right| - c_{ij} = 0
where i is not equal to j is a Holonomic Constraint.