Does anyone know how to make little patches with controlled ladders (runs) that don't take over the whole sweater?
from the picture, i think what is happening is this:
the stitches are being replaced by yarn overs, which are not being knitted in the next row.
when you want to "finish" the shape, as it were, start increasing stitches and decreasing the number of yarn overs (still not knitting them).
so for those triangle shapes you might do something like
1st row of shape: k to where you want the shape, dec 1, yo, continue in pattern
2nd row: yo, yo, dec 1
3rd row: dec 1, yo, yo, yo
4th row: yo, yo, yo, yo, dec 1
get what i mean?
and then when you want to start making the shape smaller
row 1: inc 1, 1 fewer yo than row before
row 2: 1 fewer yo again, inc 1
it's a lovely idea for a motif that i've not seen before. good luck!