No optical flow in certain directions

[BBBBBBob]

Bug report

• AirSim Version/#commit: Windows 1.6.0/ Binary 1.7.0
• UE/Unity version: 4.27.2
• autopilot version: ComputerVision
• OS Version: Windows 10

What's the issue you encountered?

In the OpticalFlow setting, the optical flow cannot be returned when the camera moves in a certain direction. Here is a video example https://www.youtube.com/watch?v=HT5wWK1M5AI: The problem could be that the velocity is mapped between the -1 and 1, but the Unreal Engine Material only returns the black color when the velocity is non-positive, even though AllowNegativeEmissiveColor is enabled.

Settings

"SeeDocsAt": "https://github.com/Microsoft/AirSim/blob/master/docs/settings.md",
  "SettingsVersion": 1.2,
  "SimMode": "ComputerVision",

  "CameraDefaults": {
    "CaptureSettings": [
      {
        "ImageType": 8,
        "Width": 64,
        "Height": 64,
        "FOV_Degrees": 120
      }
    ]
  },
  
  "SubWindows": [ 
    {"WindowID": 1, "CameraName": "", "ImageType": 8, "VehicleName": "", "Visible": true, "External": false}
    ]
}

How can the issue be reproduced?

1. Run AirSim in ComputerVision Mode
2. Move the camera horizontally or vertically

Include full error message in text form

What's better than filing an issue? Filing a pull request :).

[jonyMarino]

@BBBBBBob optical flow is not intended for visualization. Please try with OpticalFlowViz (which corresponds to ImageType 9 instead of 8 )

[BBBBBBob]

@BBBBBBob optical flow is not intended for visualization. Please try with OpticalFlowViz (which corresponds to ImageType 9 instead of 8 )

@jonyMarino Hi, thanks for your reply! Indeed, I would like to retrieve the optical flow velocity from the image, so what is the right way to get the velocity information?

[COATZ]

Hi @BBBBBBob, were you able to find a solution to get the optical flow from AirSim?

[BBBBBBob]

Hi @BBBBBBob, were you able to find a solution to get the optical flow from AirSim?

Sorry for the late reply, we have not found a feasible solution and turned to calculate the optical flow between two frames.

[KaiXin-Chen]

@BBBBBBob optical flow is not intended for visualization. Please try with OpticalFlowViz (which corresponds to ImageType 9 instead of 8 )

Though it is not meant for visualizing, but mind explaining about how to read optical flow from an png file ( a file that only has positive values from 0 to 255). I know that there is an option of using pfm files, but the pfm files it gave me only have one channel and I have no idea if it is vx or vy.

Thanks!