Texture baking and existing UV maps New to blender so the question may be silly. Ok , so having multiple objects in the scene each one with it's own UV map and texture, I want to combine those textures in a single one. I researched a little and so far I managed this by baking the texture in a new image and new UV map, but the new UV map , most of the tutorials I followed, they are generated using the smart project, I suppose you could manually unwrap each object AGAIN but makes no sense doing it all over again. Anyway, the only problem I have with this Smart project is that it changes the resolution allocated for each island if I am not mistaken , for example, I have a humanoid and I setup my UV in such way that the face takes the most resolution, but the smart project messes that up I guess, so is there any way to preserve the ORIGINAL UVs and combine them in one without the need to re-unwrap the model?
Have you tried to use the texture atlas feature? Basically you select all of your objects, create a new atlas, then chose "No_Unwrap" and "StartManualUnwrap". 

 

Manual unwrap should present you each model's UV map with correct aspect ratio. After you're done moving the UVs on the map, don't forget to hit FinishManualUnwrap.