Blobs

The example blob input file below should be compared with the first example for the spray input file. It is identical, except for the blob specific portions. Even the RenderWorld_data_file spray 5 5 line is used for blobs. However, the portion of the spray file describing the number and characteristics of spray sources has been removed, and replaced with lines for either reading in an existing cloud distribution, as in this example, or for generating a new cloud distribution for the initial distribution, as is discussed below. An addition difference between blobs and sprays is that in the scene file, the object_type blob must be used instead of object_type spray.

RenderWorld_data_file volume 1 1

nx 216

ny 216

nz 64

dx 12

dy 12

dz 15

number_of_bands 3

band_id 1 2 3

absorption 0.025 0.025 0.025

scattering_coefficient 0.1 0.1 0.1

extinction_coefficient 0.025 0.025 0.025

phase_function_file phase_functions.dat

threshold_density 0.01

scattering_flag multiple

integration_step 0.125

transmission_cut 0.01

sub_res_threshold 0.004

end

RenderWorld_data_file spray 5 5

initial_time 0

final_time 100

output_density_at_end yes

density_file density.dat

slice_the_spray yes

slicex 0

slicey 0

slicez 15

taper yes

taperx 250

tapery 250

taperz 150

taper_power 0.5

input_blob_from_file yes

file density.dat

ambient_type wind

ambient_velocity 0

ambient_angle 15 90

ambient_height 1000.0

delta_time 0.1

reference_density 4.0

air_density 0.001

gravity_flag full

random_fluctuations_flag no

small_scale_fluctuatuion_flag no

end

The alternative to reading a cloud density file as an initial distribution is to create a new blob, based on a parametric/statistical model of cloud internal structure. To choose this approach, the lines

        input_blob_from_file yes
        file density.dat

        input_blob_from_file no
        center_x: 32
        center_y: 32
        center_z: 32
        radius: 50
        height: 10
        fluctuation_strength: 0.3
        mean_density: 5

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