The GM_DensityGridParams_t type exposes the following members.
Units of area measure
How many cells in each direction to have per radius (use 0 to use default of 3 cells in each direction per radius)
Name of attribute field to compute on. Set to NULL/empty string to just count points
Flags for density grid generation
The Kernel Type
Description to use for new layer, or NULL/empty for default
Radius in meters for kernel (use 0 for a default)