There are three main aspects to the problem of comparing figures for compatibility. Each has it’s own difficulties.
The height of the figure along with the scale of any standardized equipment he has. The problem here is the skill and tools required to accurately measure a figure. Nearly all figures are in a posture which, for comparison requires measurement to include an estimation of what the figure’s height would be if it were standing up perfectly straight. The change in perceived height can vary significantly with a walking posture much less in the sort of active poses favored by gamers. To extract actual from measured height requires skill and study most people lack.
The heft of the figure, the girth of the limbs and bulk of the body. Girth in itself is, I think, the least jarring of the variations which must be considered for compatibility, far more important is proportion and to a lesser degree other elements of style such as detailing or the way some elements are depicted.
The proportions or relations of the size of the parts of the body to one another is, perhaps even more than overall height the aspect which causes most people to declare figures not compatible. As we see in figure 1. merely increasing the heft of a figure is not very disharmonious but changing the proportions causes quite a clash. (Also note that though the examples all have the same overall height the ‘figure-ized’ one, because of the distortions on the head and face has the eyes at a different level.) Even in a photograph, without a way of comparing proportions most people can’t perceive variations.
So you can’t measure your way to an adequate definition of compatibility or define it by simple notions like ‘heft’. A photograph of the figures you would like to compare side by side would be ideal but is quite impractical given the astronomical permutations. Putting a ruler or a grid in photos has several difficulties as well. Macro photography can introduce distortions depending on the placement of objects and the angle of the picture. In particular a grid or ruler behind a figure can make it appear to be quite different from it’s actual size (figure 2).
It’s to solve these difficulties I suggest posed silhouettes in photos taken alongside the figure (figure 3). As can be seen it’s only necessary to have the legs and body posture approximately match the figure.
The silhouettes should use modern natural proportions such as those established by the U.S. army because any other standard is open to dispute. I enthusiastically support any sculptors’ developing a style but how can one of these take precedence over another? Nature is self-evidently the ultimate frame of reference for representative art. This doesn't mean you must slavishly follow nature any more than your figures must be an even number of millimeters in height.
