The perspective of 3dsmax camera is the key point, any button will do, and there is only one yellow line in the security box. How to deal with it? Please give me the English version.

Select a camera (not a camera target), right-click the menu (upper left corner), and execute Apply Camera Correction Modifier, which will add a correction modifier to the camera.

In general advanced perspective, this modifier can help you straighten the perspective.

However, if there is no need to straighten, this modifier may not be the effect you want. After deleting this modifier, the camera will return to the default perspective mode.

Question 2-Right-click any button (such as zoom button) in the view control area in the lower left corner, and the viewport configuration dialog box will pop up and switch to the security frame tab. There are four rows of options to turn on the display of the inner frame of the security frame one by one.

The first three hooks should be turned on by default, and you will get the default safe box effect (3 borders) after being hooked.

In addition, the positions of these boundary areas can be customized through the following parameters.