Smooth shading across flush surfaces


As a follow-up from a previous question I want to create a sphere (a globe actually) with one particular section of the globe using a different (and higher resolution) texture than the rest. I have created a sphere, cut out a section, and created a new mesh from that section, all in blender and exported as .obj. So I have the following two meshes:

I put them on top of each other and apply the textures. However, when applying phong shading, a border can be seen. I have removed the applied texture in the image, but you get the idea:

Any suggestions on how this can be fixed?

you need this:


Works like a charm, thank you.