I just downloaded an obj file from the internet and imported it as a tool in zbrush 4r6. When i tried to paint with polypaint the brushstrokes on the model came out triangular. I think it has to do with how the polygons are arranged how do i fix it so my brushstrokes are smooth.
Polypaint colors the points (vertices) in a model. To get a good result your model must have enough points, usually at least a million. You will probably need to subdivide your model by pressing Tool>Geometry>Divide until you get the detail you want.
In addition to this remember to Remove smoothing from the Subdivide optionS toperserve the originalmodel Shape. otherwise you will loose Shape Integrity.