An apparatus, comprising: means for identifying a first set of coordinates defining first locations of anatomical points of a human in a first image captured by a first camera and identify a second set of coordinates defining second locations of the anatomical points of the human in a second image captured by a second camera; means for detecting, based on at least one of the first set of coordinates or the second set of coordinates, when the human is in a particular pose; and means for calculating, in response to detection of the human in the particular pose, a relative transformation between the first camera and the second camera 104) based on a first subset of the first set of coordinates and a second subset of the second set of coordinates; wherein the particular pose includes a projective invariant arrangement of ones of the locations of the anatomical points of the human; wherein the projective invariant arrangement corresponds to four different ones of the anatomical points being within a tolerance threshold of a straight line; wherein the calculating means is to: calculate first transformation parameters defining a first translation and a first rotation of the first camera relative to the human; and calculate second transformation parameters defining a second translation and a second rotation of the second camera relative to the human, the relative transformation calculated based on the first transformation parameters and the second transformation parameters; and wherein the calculating means is to calculate the first transformation parameters based on a triangle defined by three different ones of the anatomical points including a first point, a second point, and a third point, the first and second points corresponding to two of the four different ones of the anatomical points within the tolerance threshold of the straight line, the third point being spaced apart from the straight line. means for identifying a first set of coordinates defining first locations of anatomical points of a human in a first image captured by a first camera and identify a second set of coordinates defining second locations of the anatomical points of the human in a second image captured by a second camera; means for detecting, based on at least one of the first set of coordinates or the second set of coordinates, when the human is in a particular pose; and means for calculating, in response to detection of the human in the particular pose, a relative transformation between the first camera and the second camera 104) based on a first subset of the first set of coordinates and a second subset of the second set of coordinates; wherein the particular pose includes a projective invariant arrangement of ones of the locations of the anatomical points of the human; wherein the projective invariant arrangement corresponds to four different ones of the anatomical points being within a tolerance threshold of a straight line; wherein the calculating means is to: calculate first transformation parameters defining a first translation and a first rotation of the first camera relative to the human; and calculate second transformation parameters defining a second translation and a second rotation of the second camera relative to the human, the relative transformation calculated based on the first transformation parameters and the second transformation parameters; and wherein the calculating means is to calculate the first transformation parameters based on a triangle defined by three different ones of the anatomical points including a first point, a second point, and a third point, the first and second points corresponding to two of the four different ones of the anatomical points within the tolerance threshold of the straight line, the third point being spaced apart from the straight line. calculate first transformation parameters defining a first translation and a first rotation of the first camera relative to the human; and calculate second transformation parameters defining a second translation and a second rotation of the second camera relative to the human, the relative transformation calculated based on the first transformation parameters and the second transformation parameters; and wherein the calculating means is to calculate the first transformation parameters based on a triangle defined by three different ones of the anatomical points including a first point, a second point, and a third point, the first and second points corresponding to two of the four different ones of the anatomical points within the tolerance threshold of the straight line, the third point being spaced apart from the straight line.