Here are my settings:

enter image description here

Export settings:

enter image description here

In '.mtl'

newmtl c0
Ns 19.607843
Ka 0.000000 0.000000 0.000000
Kd 0.000000 0.077046 0.638270
Ks 0.882353 0.882353 0.882353
Ni 1.000000
d 1.000000
illum 2
  • $\begingroup$ I don't think that Ambient Cooefficient is supported by .mtl. There's more info on .mtl files here: web.archive.org/web/20080813073052/http://local.wasp.uwa.edu.au/… $\endgroup$ – CharlesL Nov 28 '13 at 18:51
  • $\begingroup$ It would help if we knew what you were trying to do and what you expect the Ambient value to be. This Ambient value is related to the render engine and doesn't really have anything to do with the material as it could be used outside Blender. $\endgroup$ – Greg Zaal Nov 28 '13 at 18:51
  • $\begingroup$ Related, Export Wavefront .mtl file — Where is the reflectance coefficient?. $\endgroup$ – iKlsR Nov 28 '13 at 18:55
  • $\begingroup$ Basically you can see Specular which is 'white' is the value 'Ks', Diffuse is 'Kd', but Ambient which is 1.0 is just 0.0 in 'Ka'. How do I change the value of 'Ka' when my materials are exported? $\endgroup$ – Joshua Barnett Nov 28 '13 at 19:42
  • 1
    $\begingroup$ @CharlesL: from the link you provided: "To specify the ambient reflectivity of the current material, you can use the "Ka" statement (...)" $\endgroup$ – Polosson Nov 29 '13 at 0:05