# Height and Multiplier Fields

Height and Multiplier grids are disturbances of the ocean. Height grids are surface vertical displacements which are added to the ambient ocean and any other disturbances that are present. Multiplier grids are applied to the ocean surface as a scaling of the surface.

The form of the multiplier disturbance in the ocean file disturbance section is

  `grid_type` `multiplier_grid`
  `n_points_x` `1536`
  `n_points_y` `1536`
  `dx` `0.1`
  `dy` `0.1`
  `detail_file` `multiplier_field.dat`
  `position_x` `0`
  `position_y` `0`
  `orientation` `0`
  `velocity` `100`
  `direction` `0`

And the form for the additive Height grid is:

  `grid_type` `height_grid`
  `n_points_x` `1536`
  `n_points_y` `1536`
  `dx` `0.25`
  `dy` `0.25`
  `detail_file` `height_field.dat`
  `position_x` `0`
  `position_y` `0`
  `orientation` `20`
  `velocity` `0`
  `direction` `20`

These disturbances have nearly identical forms in the ocean file. In the referenced detai files, the differences are more critical:

For the multiplicative height fields, the detail file is:

  `RenderWorld_data_file` `multiplier_grid` `1 1`
  `multilplier_file` `wake2.img`
  `number_of_scaling_key_times:` `1`
  `time scales`
  `0. 0.`
  `end`

The hdf file wake2.img contains a single array representing the multiplicative factor to be applied to the oceans surface. The scaling factor listed here as changing over time affects the ocean surface as an exponent power on the data. The hdf file is rescaled by raising the multiplier value to the scale power.

For the height disturbance in the example below, the scaling parameter is now applied direct to the height_grid as a multiplicative factor.

  `RenderWorld_data_file height_grid 1 1`
  `height_file_name:` `wake2.img`
  `number_of_scaling_key_times:` `4`
  `time scale`
  `0 0`
  `1 1`
  `2 3`
  `4 0`
  `end`

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