OK its not bad also without glasses, but looks a bit strange..with glasses it would look better in my opinion..but that's just my guess.
Anyway if your model has a part that represents the glass then there is no need to use any image file for the glass.
Just name that part "glass" in your 3D software before exporting. Then once imported in outerra open the .mtl file and edit the entry "glass" as follows.
{
"name" : "glass",
"color" : "0.5,0.5,0.5,0.15",
"f0" : "0.539",
"roughness" : "0.3",
"no_light" : false,
"alpha_masked" : false,
"emissive" : false,
"emissive_color" : "",
"tex_albedo" : "",
"tex_normal" : "",
"tex_roughness" : "",
"tex_opacity" : "",
"tex_reflectance" : "",
"tex_environment" : "",
"tex_emissive" : ""
},