Reloading FBX file

Hello to all. We are an architectural company who uses REVIT to model. I have managed to export my model into FBX by using another Rendering software’s PLUGIN :). It works pretty well. My question is when i try to reimport revised model into UN4, All materials that i paint in UN4 lost. I need to repaint them again which takes time. What i need is to keep those materials in UN4 but revise main model. You can find a summery in the attachment.
Best Regards…

first of all, that big a thing shouldnt be one model, cut it into pieces and export them seperately.
2nd, are you vertex painting or just applying materials?
again, if its one big model with multiple materials you are working way less than optimal.

Thanks for your quick response. First of all we are at the beginning level. I have tried different model which contains only four wall ( Very small size) unfortunately we have the same result. At the begining, We introduced just one material and revised the model. It was worked without any problem but when we introduce more than one material, the same problem repeated after reloading. I think we are appling materials.
We need to achieve link model from revit to UN4 but keeping materials which is applied in UN4. The process smilar with 3DS max and V-ray relationship.

For optimisation reasons, you should always try to use one material per mesh, but there are always instances where this is not possible.

I cant help you with the particular reason at hand because i have no experience with Revit, I can ask some questions to narrow down the problem though.
(Also, its UE4 not UN4)

  1. the materials, do you export them with revit?
  2. did you create the materials in UE4?
  3. have you tried disabling import texture/create material on import?

Dear Luos
thank you for your kind answer and fixing me about naming. As i said i am a beginner. UE4 is a great program but i really do not understand why they limit its capabilities with gaming. Most of the arcihects uses revit, archicad, allplan, rhino to produce their models and it will be very diffucult for us to remodel them in UE4 again to use program efficiently and we always revise our models. There are some other rendering programs such as Lumion, twinmotion,artlantis who take this problem seriously and produce plugins. I am pretty sure UE4 is better than all these programs but it is useless now for me unless i can not fix this reimporting problem. thank you best regards

In a few hours I will be home, is there a chance we could get on a google hangout so I can see where the problem is?

Dear Luos,
Sorry for late reply. I don’t use google hangout but i will explain what i am doing while reimporting later.
thank you for your consideration…