"I'm used to kids breathing down my neck," he says cheerfully, having sketched quickfire requests at the Lantern Festival. "They shout out whatever: shipwreck, tree, Pokemon."
But today Ha is interested in creating balance, harmony and movement in a depiction, about 3m long, of the Milford Sound. "Clouds and trees work with wind to create the landscape," he says, the direction of the leaves and branches being very important. A mountain sits slightly "off to the side" as the focal point. Symmetry is not the same as balance, he says. Instead, the aim is to guide the viewer's eyes smoothly through the work in a figure-eight, yin-yang movement, "like qi that never dissipates".
The long scrolls - Ha's record thus far is 100m - are used because "a square space is hard to move around".
Leaving white "breathing" space is important, too. Below the mountain is a vast absence of paint - a lake. It doesn't contain any reflections because he's trying to give "the feeling of something being full rather than trying to fill it up". Less is more - and more mysterious.
Most of his art students are young Pakeha. Ha says that "New Zealand Chinese think they don't need to have anything to do with China." He disagrees. "China is going to be big; I see the future moving that way. If we don't learn this, how are we going to communicate?"
He's not necessarily talking about learning painting itself, but the ethos that underlies many Chinese expression forms, including tai chi: balance, harmony and movement.
