Unity3d import of Max files

1. Axial deflection
After the max model is imported into unity3d, the X axis will automatically deflection-90 degrees. Unity3d uses the left-hand coordinate system, while 3dmax uses the right-hand coordinate system. Helpless, this is a problem that many game engines will encounter when combined with Max. Compatibility problems !! Silly X, Max. The vast majority of 3D software in this world is TMD's left hand. You have to be right .. Mainstream...
That is to say, after Max enters unity3d, the Z axis is up, while the spatial coordinate is up on the Y axis. Don't think it's a small problem .. If you use a program to control the point of an object, the trouble will be high. Mom forced ..
Solution: import the model to the 3DS file and then to unity3d. Instead of fbx officially recommended. Fbx is no different from Max. What is the problem with Max? fbx also has that problem. (Z up or y up in the export settings in fbx are meaningless)

2. Unit problem (scaling factor problem)
The unit of the unity3d physical system is meter (m ). That is to say, if position X is 1, it is to move 1 meter in the X direction.
Case A: When the max system is measured in meters, a box with a length, width, and height of 5 meters is created and dropped into unity3d to 5 cm.
Case B: When the max system is in centimeters, a box with a length, width, and height of 5 cm is created and thrown into unity3d, which is 5 cm.
In case C, when the max system is in centimeters, a box with a length, width, and height of 5 meters is built and thrown into unity3d, which is 5 meters.
It can be seen that the unity3d recognition is correct when the max unit is centimeter .. So why is the meter wrong? Is building done in centimeters?
After a lot of experiments, I found a very good problem.
Max's system unit settings have no significance for unity3d !! Unity3d does not care about the max unit at all. The official document says that the Max file can use the File unit, which is farting ~~~
A. B. C. Let's skip to the max system unit.
In a, the box is 5 units. After Entering unity3d, It is 0.05 units, which is reduced by 100 times.
In B, the box is 5 units. After Entering unity3d, It is 0.05 units, which is reduced by 100 times.
In C, box is 500 units, 5 units after entering unity3d, which is 100 times smaller.
To put it bluntly, it will be reduced by 100 times when it is thrown into unity3d, which has nothing to do with the unit.
Why is it reduced by 100 times?
When the max model is imported into unity3d, the scale factor in the import settings is 0.01 by default, which is 100 times smaller. Uh .. Okay... You win ..
Since the max system unit is meaningless, you will not hesitate to cancel the use file units option in the import settings.
Then, you do not need to use a special system unit in the max modeling. You can use a scaling factor to control the size during import.
For example:
During building modeling, the max unit is considered as meter. Set the scaling factor to 1 during import.
During role modeling, the max unit is regarded as centimeter. When importing, set the scaling factor to 0.01.