What Filters Do In Maya
Filters basically smooth pixels. Whenever you create a file node in Maya, you'll have a filter type option.
By default, it's set to quadratic.
Now select the wall, go to the rendering shelf and click the wavy checkerboard icon.
This will open the attributes editor to the material that's assigned to
the wall. Click the black arrow adjacent to the text Color (most
average users already know that this'll take you to the node that's
connected to the color. In our case, it's a file node.).
Continuing where we left off, let's check this attribute. Now when you render it, the wall texture seems to be blurrier. Now, the higher you set pre- filter radius attribute the more blurred your texture will appear. This can come in handy when you have a low resolution map and you don't want it to appear pixely.
When To Turn Filtering Off
The main time to turn the filter off is when the texture appears too blurry. An example of this is you have an image with text on it that you've assigned to a 3D model. Depending on the size of the text, it might be hard to read. So it's better to turn filtering off.