depthmap bug: The small sensor_size will cause depthmap results error

[XiangLiu0731]

TASK DESCRIPTION
System Information
Operating system: Windows 10
Graphics card: RTX 2080 SUPER

Blender VersionF12968783: bug.blend
Worked: Blensor 1.0.18 RC 10 Windows

Short description of error
When the sensor width is set small, the result of the depthmap is incorrect (the scale of scan result is not consistent with the object).

Exact steps for others to reproduce the error
Based on the default startup, we set the camera focal length to 35mm, set sensor width to 5.632mm, and the scanner type is Depthmap. When the camera's location is (0, -20, 0), we press the "Single scan" button, and the scan result is incorrect.