百度地图java script api，为啥调用地球地图时，总是出现这种类似夜间模式？不想要这种，求解，为什么！还望大神解答解答疑惑，
```javascript
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>百度地图</title>
<style type="text/css">
html{height:100%}
body{height:100%;margin:0px;padding:0px}
#container{height:100%}
</style>
<script type="text/javascript" src="https://api.map.baidu.com/api?v=3.0&type=webgl&ak=你的密钥">
</script>
</head>
<body>
<div id="container"></div>
<script type="text/javascript">
var map = new BMapGL.Map("container");
map.centerAndZoom(point, 15);
var scaleCtrl = new BMapGL.ScaleControl();
map.addControl(scaleCtrl);
map.addControl(new BMapGL.MapTypeControl({mapTypes:[BMAP_NORMAL_MAP,BMAP_EARTH_MAP]}));
</script>
</body>
</html>
```
