Some questions about depth

Recently I'm trying to use depth frame in AI2-THOR to do something. So I read all codes about depth in detail and have the following questions.

1. In [ImageSynthesis](https://github.com/allenai/ai2thor/blob/main/unity/Assets/Scripts/ImageSynthesis/ImageSynthesis.cs#L93) line 93 to line 102, why do you use different shader when in and not in Unity Editor? Does this operation refine some efficiency or something?
2. There are two shaders for depth rendering: [Depth.shader](https://github.com/allenai/ai2thor/blob/main/unity/Assets/Scripts/ImageSynthesis/Shaders/Depth.shader) and [DepthBW.shader](https://github.com/allenai/ai2thor/blob/main/unity/Assets/Scripts/ImageSynthesis/Shaders/DepthBW.shader). I understand operations in Depth.shader that you want to use 24-bit (3 8-bit RGB values) to store a float depth. However, DepthBW.shader will generate a relatively big error. Is this error in depth acceptable?
3. In Python code, I think codes for dealing with depth frame is [here](https://github.com/allenai/ai2thor/blob/main/ai2thor/server.py#L279) line 279 to line 303. If I am right, then line 292 and line 293 seems not to be executed forever. And I also think line 294 should be
```
image_depth_out *= multiplier / 255.0
```
since the max value for a pixel is 255.

Maybe I wrongly understand something, but I hope this issue can be replied! Thanks in advance!