fix:

public/static/lib/potree/potree.js

@@ -91597,7 +91597,7 @@ void main()
 	                    if(viewer.mainViewport.view.isFlying())return
 	                    
 	                    let dir = directions[name];
-	                    if(name == 'top'){
+	                    if(name == 'Top'){
 	                        let baseLine = viewer.scene.measurements.find(e=>e.isBaseLine && e.points.length == 2);  //使基准线在俯视图中水平
 	                        let yaw = baseLine ? new Vector2().subVectors(baseLine.points[0], baseLine.points[1]).angle() : 0; 
 	                        dir = baseLine ? {dir: new Vector3(0,0,-1),yaw,pitch: -1.5707963267948966} : directions[name];