problems about ground and tree model color

[Elephant-C]

Hi there,

I'm interested in ALS data simulation. Helios is quite good and it can meet nearly all my needs. However, i encountered with some problems when simulating ALS data with Helios.
Firstly, I follow the Wiki instruction to generate .mtl files with blender and try to import .obj models into Helios. However, only one tree was successfully merged with color information and this problem also shown in importing DEM to Helios.(please refer to figure 1 and figure 2)
Secondly, There is no ground information in simulated data after replacing the default groundplane with other DEM .obj file(please refer to figure 2)

Could you please tell me how to fix this?

Figure1:

Figure2: