Feature
 v1
 v2

Resolution
 Fixed to 1km with some degradation with distance
 Multilayer/Multiscale from 20m

Point spread function with 1st scattering only



Point spread function with 2nd scattering



Radial comparizon v1 v2
 Single scattering
 1st and 2nd order of scattering

Line of sight
 Voxels sticked to a fixed 3D grid (1km x 1km x dz)
 Mini voxels of 1m^{3} with an initial resolution of 19m with a multiplicative factor of 1.12

Modeling grid
 fixed horizontal grid (1 km) plus a fixed exponential vertical grid
 No vertical grid for the line of sight but fixed resolution grid for the calculation of the 2^{nd} order of scattering. That grid is centered on the mean position between the lamp and the line of sight point and is approching a sphere in shape with a resolution of 2.5km. The maximal allowed height is either 35km or the cloud base height.

Ground reflectance
 Variable on each grid point according to the reflectance product of MODIS
 Fixed all over the domain but obtained by combining some typical surface reflectance spectra

Overhead clouds
 Fixed cloud base height per cloud type. Cloud type to be defined by user.
 Cloud base height and cloud type both defined by the user separatly.
Cloud fraction introduced

Topography screening
 
 Improved horizon blocking scheme

Scattering probability
 
 Completly new and more accurate scattering probability equations

Extinction
 
 Completly new and more accurate transmission equations

Solid angles calculations
 Using the coarse fixed 3d grid of the model and some approximations depending of the viewing angle and the vertical layer thickness.
 Accurate calculation using a unity 1m^{3} volume

Separated cloud radiance printout
 Cloud radiance not separated from the total radiance
 The radiance from clouds and the total radiance is given in the output file

Adding the calculation of the direct radiance radiance
 No direct radiance considered
 Direct radiance both from lamps and from refleting surfaces

Line of sight below horizon
 Minimum elevation angle of 0.5 deg
 Any elevation angle allowed
