Adjust anti-aliasing options in the Render Settings window.
Select the Maya Software tab in the Render Settings window. The options in the Quality drop-down list and the Edge anti-aliasing drop-down list drive each other; when you change one, the other changes, and values for the Anti-aliasing Quality subsections are automatically filled in. You can fine tune any of these settings.
Do one of the following:
Select the Maya Hardware 2.0 tab in the Render Settings window. Expand the Anti-aliasing section to enable either Smooth Wireframe or Multisample Anti-Aliasing, and adjust the sample count. See Viewport 2.0 Options.
Refer to the Arnold for Maya User Guide for information on the sampling controls provided with the Arnold for Maya renderer.