From ICM's link.. Turn Anti-Aliasing Off for a Single Object or Group Select the object or group, then go to the Attributes Menu. Hold the Ctrl/Shift/Alt keys and exit the menu using the green check. To turn Anti-Aliasing for the object or group back on, go to the Attributes Menu and hold the shift key while exiting using the green check. This works only for certain objects, trees not included. It doesn't work with alpha planes either, I find. I get round that by doing an object mask, rendering the object with AA turned off, then layering it into the final render. If you're doing it to save render-time, then you have to make the objects hidden in your AA render, and that can cause problems with shadows. There are work-arounds though, add the shadows in postwork, or plop-rendering to include the shadows, and using them as a guide in postwork. Or hopefully someone else will have a better suggestion ;^)