Imposter scale fix:
"Problem is in the MaterialFunction "/Engine/Functions/Engine_MaterialFunctions01/WorldPositionOffset/FoliageScaleFactor". Both of the TransformPosition nodes are set to output Local Space, the same as the inputs. Change their Destination to output Absolute World Space. This fixes the problem of the mesh instances scaling with the billboard sizes correctly.“
https://forums.unrealengine.com/development-discussion/rendering/97944-imposter-billboards-don-t-scale-with-mesh

10 unique pine trees, showcase scene
PBR Materials
Albedo, normal, roughness
Up to 4096x4096 Textures
Pivot Painter 2.0 animation
3 stages of LOD's (imposter last lod)
Collision also included

Technical Details​

Props Scaled to Epic Skeleton: Yes
Physically-Based Rendering: Yes
Collision: Yes, Custom and Generated
Triangle Count: 400 - 36000
LODs: 3 (Including Imposter Billboards)
Number of Meshes: 10
Number of Textures: 8 + imposter generated atlases
Intended Platform: Windows, Mac, Linux, Htc Vive
Platforms Tested: Windows, Htc Vive
Documentation Included: No