Anyone know why my object turned 100% black after successful light rebuild ?..also is it best to drop new fbx model ( modeling updates) into directory where the uasset resides and willl it just update that uasset file, if not how should be done ?
Regarding black object, I tried dragging in the default sandstone texture onto object, and it remains 100% black.
Thx for any help with these issues 
nl
Most likely you donât have the right lightmap UVâs setup. If you need to update an object you can right click it and click Reimport (as long as you overwrote the original source file). Or you can go to Import and select the file again and itâll overwrite whatâs in the content browser.
It could be a light map problem but the compile log should tell you if the object has a light map problem. If it compiles without errors it might be the same problem that Iâve seen when importing mesh from 3ds to other editors that turned out to be a scaling problem.
Assuming 3ds > UE4 the only time the true âlocalâ scale of an object is known is upon creation of a procedural primitive. Once converted to a poly edit your now editing the objects relative scale with in world space but the local scale will still be set to what it was when created.
Sooooo
When you import an object into an environment that uses the local scale of an object, such as a game engine, then any kind of lighting solution will be based on that value which could be micro small or bigger than a Death Star so although the object is relative the math is telling the render engine the object is either bigger or smaller than it is and renders black.
If thatâs the case the way to fix it is to use the old school xform reset found under utilities that will force the scale of the object to the relative scale, and fix a few other things, and is a tool thatâs been used forever to fix unusual stuff like .
Not using or maya, as I use sculptris at the moment ( no animation atm, etc.). I exported obj and thatâs what I imported, so Im afraid the xform thing wontâ help me. I"ll try once more and see if export went bad.
One annoying thing that Im not sure is taking far too long,or is just computationally very longâŚWhen I compiled lighting , with lightmass, that was recommended by ue4, it starts out fine , but then it remains on 0% forever. Could it be I made lightmass importance volume too large ( It was supposed to speed up light building time, but that has no happened obviously) ? I surrounded black object entirely in lightmass , and object scale acc. to editor is 50.25 on all axi .
One last thing,is there no way to save my current OBJ transform values, in UE4 editor, to avoid a reimporting of obj (as it changes over time) messing up the transforms which need to be precise , or will it not mess with that and leave obj in game as is ?
Ok good. When the updated mesh comes in, will it avoid overwriting my current transforms ? I have very specific values that must be maintained, as if it doesnât, I"ll need to write down the values. Asking so I donât mess up a ton of time trying to get it just right. Lastly, why would my lightmap UV"s be wrong ? Is there a special way I needed to export the OBJ from sculptris or a different tool I should be using to avoid ? Oddly , upon initial imported as noted earlier, it was just fine , not all black that only occurred when I built lighting .
thx
nl
When you update the object in the content browser it updates every instance of it in the level, each object you place in the level is referenced from the content browser, so any transform values you have will remain.
Sculptris isnât really designed to export directly to games, to setup lightmaps youâd need some way of editing the UVâs
May I ask , is the lightmap you refer to , something that the FBX format does on export ? Maybe I could convert from obj to fbx then would that fix âŚ
Im very confused why we are talking about UV"s and lightmaps. I know what UVâs are, but Iâve never heard of them as relates to lightmaps. Are you saying to bring in a OBJ and not have a black material about building light, that I need to bake a lightmap ?
Btw also, I wonder if my problem is that the lightmass importance volume isnât âbound tightlyâ âŚI have no idea what on earth that even means, could it be that I didnât do that,that Iâm getting the object to display all black ?
Sorry ,but Im trying to cover all bases so I can get working asap, as Iâm stuck here.
thx!
nl
You have to create a lightmap for your mesh:
âNormalâ uvâs are here for the texture (that it gets displayed right):
A lightmap is a uv on a 2nd uv channel which is for the light (see upper links) 
OK, well I guess I assumed incorrectly that ue4âs lighting did all that, so thx for clearing that up, very nice! 
cheers
nl
One other thing to add on subject, if you have anything plugged into the Ambient Occlusion input in your material, it might be worth toning down the intensity. stumped me for ages on a level I was working on a while back where meshes came out almost completely black, and it was because the AO appeared to be on steroids according to lightmass. Didnât occur until I built lighting of course, but itâs worth checking out!
argh, where is setting btw ? I looked and found nothing.
BUMPiing because I canât find abm. occlusion input you refer to.
If you donât know what it is then you donât have it, itâs something you would have to specifically do on purpose, not something youâd do by accident or have by default.
Btw I thought Iâd mention, that ( while you did say not recommended) the âblenderâ method doesnât seem to work, I tried it. I made the second UV channel, but it still shows only ONE in UE4 browser ( double click imported object in that window).
Maybe is truly broken for blender ? Makes me sure wish I had maya at times like .
Maybe it no longer matters, as the new (*which I canât get atm due to finances) UE4 has being done automagically
later
nl
Hmm, normally it should work -> but I will try it out when Iâm at home
OK awesome,ty so much for your continued help.
If that specific URL does not work, I hope someone can create one, or offer words here on whatâs missing from the video , to make work from BLender > UE4
cheers
nl
Just checked it an it should work -> make sure to choose the right uv channel in the static mesh editor (otherwise it will display the wrong one) + could you post your steps
I thought, importing mesh along was enough, so I have to then go into static mesh editor and choose the âlightmapâ channel ? Trouble is, when I view my object in that editor, it shows only ONE uv channel,that is the problem.
Ok so that videos above seem to be a bit outdated. Also you cannot seem to âgenerate unique UVâsâ from the editor in 4.5 anymore. So I am stuck with black static FBX meshes if I bake the lighting. Even after re-exporting as FBX 2013 from 3DS it doesnât resolve it. (I am very new at and trying to build some VR demos and would prefer it to be as easy as possible like it was Unity getting a model imported.) All of the models Iâve purchased online and somehow import they all import to unity just fine with their terrible UVs.
guy bshapiro describes my problem better than I can, even though itâs an old post: https://forums.unrealengine/showthread.php?1600-unity-assets-to-ue4
Also another separate request that would save me soo much time: https://answers.unrealengine/questions/122999/difficulties-with-fbx-and-texturesauto-assigning-m.html
I read that âBrianâ is trying to make the lightmapping process easier at least and that is great news, source: https://answers.unrealengine/questions/108433/ue-45-preview-auto-generated-lightmap-uv-has-overl.html
