How can convert affine to Jacobian coordinates?
When you go from Affine to Jacobian, $X$ and $Y$ stay the same, and $Z$ is equal to $1$

Affine -> Jacobian:

$(X',Y',Z') = (X,Y,1)$

Jacobian -> Affine:

$(X',Y') = (\frac{X}{Z^2}, \frac{Y}{Z^3} )$