Lightmapping from C4D to Unity does work fine providing you follow some rules. However to be honest, unless you require an extremely defined lightmap that maybe uses IES lights you are fair better to do the lightmapping inside of Unity using their inbuilt BEAST system. You achieve very nice results with it but the workflow is far easier and faster, especially if you need to tweak/change your lighting after importing your scene/models into Unity. BEAST is literally a 1 minute job to redo an existing lightmap in Unity. If you need to redo a lightmap in C4D or any other 3D app to Unity, the workflow becomes cumbersome because you need to reset your Lightmap shaders in Unity. This becomes painful if you need to lightmap many objects with multiple lightmaps. BEAST also has the advantage of easily changing how much space each model is allocated per lightmap, hence objects in the distance can be allocated small amounts of space leaving the majority of the lightmap to provide higher quality lighting for close up objects.
EDIT UPDATE: The following process (albeit tedious) used to work in R12 however I have just tested in R13 and discovered that C4D is no longer exporting multiple Materials per object to Unity again (an issue in R11 I reported to MAXON that was fixed in R12). The two UV channels are still working, however without export of more than one material per object the process fails. See my Unity post on this http://forum.unity3d.com/threads/60761-C4D-to-FBX2010.2-to-Unity-workarounds?highlight=c4d+lightmap
If you still wish to lightmap in C4D to Unity here is how (I used this process prior to BEAST being part of Unity). Use this process at the mercy of MAXON keeping FBX up to date and working (hence why I use BEAST):
1. After applying your base material (can contain bitmap of not) ensure your texture tag is placed to the left of your material in the C4D Object Manager.
2. Create a plain white material RGB = 255, 255, 255 with colour channel activated only
3. Apply this white material to all objects you wish to lightmap (leaving original base materials in place on objects).
4. Search for the "Bake Object" tag in the Customise Pallettes Manager and drag onto your menu or new pallette.
5. Select the objects you wish to bake in the Objects Manager and then click on the "Bake Object" icon to bring up the options for this tool.
6. Check "Illuminate" and "Single Texture" then set supersampling to 1 and leave pixel border as 2, then input the size of the map you want ie, 512x512
7. Click bake
8. You will now see your objects duplicated at the top of the Object list and with a new baked material containing your lightmap in the Luminance channel. Select the texture tag and baked material from each object and drag to the corresponding original object (to the right of the original material on each object). this will mean you now have two texture tags and two material per object/model. Ensure the new texture tag is also placed to the left of the baked material. This will then allow FBX to export out the two UV sets for Unity to recognise.
9. You can now deleted the baked duplicate objects. Note: It doesn't matter which objects you use or drag the texture tags and materials onto as both are identical.
10. In the material manager, select your baked lightmap material and activate the colour channel. Now copy the Luminance channel (lightmap texture) into the Colour channel and deactivate the Luminance channel. Unity/FBX doesn't recognise C4D's Luminance channel.
11. Export to FBX and save the exported file into you Unity project "Assets" folder.
12. In Unity Select your original object base Material and change the Unity shader to Legacy Sahders>Lightmapped>Diffuse
13. Now drag your lightmap into the lightmap texture slot.
Edited by artzfx, 24 July 2012 - 11:29 PM.