The tutorial seems to be using a default camera for the Raycast, make sure you have a camera in the scene that has its Tag set to Main camera.

本教程是使用默认的相机对光线投射，确保你的场景中的摄像机，其标签设置主相机。

youdao

Other than the default camera application, Android Market has quite a number of camera applications with interesting features as free downloads and paid applications for as low as $3.

除了默认的摄像头应用程序，Android软件商店里还有很多免费的和付费的摄像应用都具有相当有趣的功能，即便是付费的也很便宜，只需3美元。

youdao

By default, the video coming in from the camera is not in an RGB format.

默认情况下，来自摄像机的视频不是rgb格式的。

youdao

For many people their phone is now their default camera and they have many hundreds or thousands of photos on their phones.

FORBES: Facebook Now Auto-Uploads Mobile Photos To Web

Trainor said that the mobile phone is the default digital camera and video camera for many people, and the challenge is using the technology to allow users to create better videos.

FORBES: Are GIFs The Future For Mobile Video? Vimeo Thinks So

While far from perfect, there's a lot to like about Nokia Creative Studio -- the panorama capture alone is worth the price of admission (which is free, unlike the alternative) since it's missing from the default Lumia camera app.

ENGADGET: Nokia Creative Studio brings panorama capture to Lumia handsets (hands-on)