# The boundary of an implicit_plot3d are jittery.

I am making a contour plot in a restricted region using the following commands:

```
var('x,y,z')
implicit_plot3d((x^2+y^2-.4)*(x^2+z^2-.4)*(z^2+y^2-.4)*(x^2+(y-z)^2/2-.4)*(z^2+(x-y)^2/2-.4)*(y^2+(x-z)^2/2-.4)*(x^2+(y+z)^2/2-.4)*(z^2+(x+y)^2/2-.4)*(y^2+(x+z)^2/2-.4)==1, (x, -3, 3), (y, -3,3), (z, -3,3), color='green', plot_points=100, region=lambda x,y,z: x^2+y^2+z^2<10)
```

The surface is restricted to a ball, using the region command. This is because I need to illustrate a surface with its boundary meeting the corresponding sphere.

My problem is that some of the boundary cylinders have their border very jittery. They look like a saw. I need them to be smooth, as some others actually are.

I tried using Adaptative=true, without any success. The same problem also applies when I use tachyon to render rather than jmol.

Any suggestions would be welcome.

Thank you