Peter Elsea did a nice tutorial about it : Peter Elsea - Meet repos
Jit.repos is often used with jit.expr for generate spatial map.
Nice results are obtained by using interpolation, change the interpbit attribute for that. At 0 there isn't interpolation, at 1 the dimension of your spatial map matrix must have twice the dimension size of your left input jit.matrix etc...
(please list things that you believe to be errors or omissions from the existing refpage)