An imported file having a png texture with an alpha channel do not show the tranparency.
Ex. A SketchUp tree file imported into Artlantis. The tree is made of a trunk and many facets on these facets a texture of a leaf is set with a cutoff for the transparency. The transparency is seen into SketchUp but not into Artlantis.
In Artlantis into the list of Shader select the png file then into the Shader's inspector check the box Transparency, but this is not enough, you need then into the list to select the Shader then into the Shader's inspector set the Diffuse to black color and the Transparency to white.
4.1 5.0 5.1
Mac OS 10.6.x
Mac OS 10.7.x
Mac OS 10.8.x
Mac OS 10.9.x