if (height.rows() < 2 || height.columns() < 2) {
throw new IllegalArgumentException("height must have at least two rows and two columns");
}
Box3 bounds = new Box3(xz.spanX(), height.range().expand(MathUtil.EPSILON), xz.spanY());
this.grid = new Grid3(bounds, height.rows() - 1, 1, height.columns() - 1);
this.height = height;
}