Here is after a few tests... My workflow to reduce the number of polygons of the element scanned by RealityCapture without losing quality /// I used the reprojection of the low poly on the high poly and I unfolded the uvs in using polygroups, ambient occlusion too... I then re-imported and retextured the low poly model under RealityCapture /// To finalize I baked the model under substance painter to obtain the different maps (normal map... etc.) here is the very nice result! more than exporting it under the Unreal Engine 4 or Unreal Engine 5 /// :)