ui/src/main/java/ucar/nc2/ui/geoloc/Navigation.java
public boolean wantRotate(double displayWidth, double displayHeight) {
    getMapArea( bb); // current world bounding box
    boolean aspectDisplay = displayHeight < displayWidth;
    boolean aspectWorldBB = bb.getHeight() < bb.getWidth();
    return (aspectDisplay ^ aspectWorldBB); // aspects are different
 }
public boolean wantRotate(double displayWidth, double displayHeight) {
    getMapArea( bb); // current world bounding box
    boolean aspectDisplay = displayHeight < displayWidth;
    boolean aspectWorldBB = bb.getHeight() < bb.getWidth();
    return (aspectDisplay ^ aspectWorldBB); // aspects are different
 }
calculate if we want to rotate based on aspect ratio