Population size and geometry

A population, defined by the <pop> object, consists of a set of units typically arranged on a cartesian grid. The geometry of the population is specified using the following object:

<geometry>
        xn  16           # Number of cells in x-dimension [Area xn?]
        yn  16           # Number of cells in y-dimension [Area yn?]
        zn   4           # Number of cells in z-dimension [1]
        x0   8           # Origin w.r.t. Area origin [0]
        y0   8           # Origin w.r.t. Area origin [0]
        xf   1.0         # Scaling w.r.t. Area (or stimulus grid?) [1.0]
        yf   1.0         # Scaling w.r.t. Area (or stimulus grid?) [1.0]
        oddxoff 0.0      # x-offset of odd row numbers [0.0] (grid units)
</geometry>

Values that are not specified default to those given for the area to which the population is assigned, or to fixed values, as specified above.

An <area> is defined as follows:

<area>
     name  v1           # Name to identify this area [exit]
     xn    16           # Size of area in x-dimension [exit]
     yn    16           # Size of area in y-dimension [exit]
     x0     8           # Origin w.r.t. stimulus grid [exit]
     y0     8           # Origin w.r.t. stimulus grid [exit]
     xf     1.0         # Scaling w.r.t. stimulus grid [1.0]
     yf     1.0         # Scaling w.r.t. stimulus grid [1.0]
     umx   59.0 (um)    # micons per Area grid unit [0.0]
     umy   59.0 (um)    # micons per Area grid unit [umx]
</area>

The stimulus grid is defined by the following top-level parameters:

xn      16           # (pix) Size of stimulus in x-dimension [exit]
yn      16           # (pix) Size of stimulus in y-dimension [exit]
sscale   0.04        # (deg/pix) spatial scaling of stimulus grid [exit]