Why do my materials look glossy after I export into Viewpoint?

Typically, if a material exports out with a glossy look, the problem lies with the default procedural lightmap or lightmaps in general. Simply increasing the resolution of the textures will not alleviate the problem.

So, how do you fix this problem? First of all, you should open your scene in Scene Builder. There, under the Materials menu on the right hand side, you will see the Lightmap Lab, in which you can adjust the procedural lightmaps. Note that "procedural" means that the lightmap descriptions are written into the MTX (XML text scene description file.) If no lightmaps are explicitly stated in the MTX, then the plugin will render the scene with a default setting. Sometimes this default setting makes materials look glossy when you export.

Note that you can assign lightmaps either globally (to the entire scene) or locally (to an object in the scene.) In order to assign a map locally, simply right-click on an object in Scene Builder or choose its name from the right-hand Instances hierarchy list.
Once you are in the Lightmap Lab, you have a number of options: intensity, specularity, colors... Note that you also can choose to add more than one light to a lightmap. Adding more lights can do a number of things, including distributing the overall lighting more evenly. Obviously, this overall procedure takes time and requires a certain amount of experimentation- and artistry!

Once you've created the "perfect" lightmap, you may want to reuse it. How do you do this? One way would be to cut and paste the lightmap tags out of your MTX with a text editor. You might save this as "NonGlossyLightmap.txt" or whatever. Another method would be to hit the "Save As JPG" option in Scene Builder. This writes out a jpg image that you can load either globally or locally.

Using a jpg-based lightmap means that the lightmap is no longer procedural. Rather, it becomes external. Any image that is 256x256 pixels can be a lightmap. Of course, you would use an external lightmap to create a much more specific light or material quality. For instance, you can apply an external lightmap to a sphere to make it look like it's made of shiny metal. Viewpoint offers a number of "Atoms of the Week" that include all sorts of material lightmaps- steel, aluminum, etc. Note that if you create an external lightmap in the Lightmap Lab, you will probably want to edit it in Photoshop or another image editing program. This editing can include changing the contrast, the values, the hues, etc.