Sorry for the late reply I got busy,
Now for the UE4, I cannot answer that since I don't use it,
For the FBX viewer, I did a quick test, you'll see in the screenshot below two views
Taken from two opened FBX viewers. The left image is a box with dimensions: 5m x 5m x 5m
And the system units is set to Meters. Then, I changed the system units to Centimeters, applied
An Xform then collapsed the Box and exported the model again(the image on the right)
The Box now is: 5cm x 5cm x 5cm. As you can see the second Box is 100 times smaller than the one
On the left. The major grid lines size in the FBX viewer is 1m, and the small ones are 20cm each. So,
Personally, everything worked normally.
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miledrizk@gmail.com
3DS Max 2021, V-Ray 5.2
3DS Max user since 2003 (3DS Max 7)
V-Ray user since 2008 (V-Ray 1.47)
My YouTube Channel http//www.youtube.com/c/MiledRizk