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royale-ros: Inspecting and configuring the camera/imager settings

royale-ros provides access to the camera/imager parameters via the Dump and Config services on the camera nodelet. The approach employed by royale-ros is to encode the settings via a JSON serialization. To inpsect the settings you use the Dump service to get a JSON encoding of the parameters. To mutate the settings you use the Config service by providing a JSON serialization of your desired settings. Specifics on how to use these services now follows.

NOTE: In some of the examples that follow, we use the jq command line tool to process the royale-ros JSON stream via a Linux pipeline. If you are on Ubuntu, you can get jq via sudo apt-get install jq.

The Dump service

To dump the camera settings, you can directly call the Dump service via rosservice or call the service from your own code and process the JSON there. Using the rosservice command line tool, this looks like:

$ rosservice call /camera/Dump
config: {
  "Device": {
    "Id": "0005-4804-0050-1916",
    "Name": "PICOFLEXX"
  },
  "Imager": {
    "CurrentUseCase": {
      "ExposureLimits": {
        "57082": [
          "27",
          "2000"
        ]
      },
      "ExposureMode": {
        "57082": "0"
      },
      "FrameRate": "5",
      "MaxFrameRate": "5",
      "Name": "MODE_9_5FPS_2000",
      "NumberOfStreams": "1",
      "Streams": [
        "57082"
      ]
    },
    "MaxSensorHeight": "171",
    "MaxSensorWidth": "224",
    "UseCases": [
      "MODE_9_5FPS_2000",
      "MODE_9_10FPS_1000",
      "MODE_9_15FPS_700",
      "MODE_9_25FPS_450",
      "MODE_5_35FPS_600",
      "MODE_5_45FPS_500",
      "MODE_MIXED_30_5",
      "MODE_MIXED_50_5"
    ]
  }
}

While calling the Dump service via rosservice is easy and convenient, it is non-optimal as rosservice's own mark-up (see the config: at the begining of the output?) produces invalid JSON for processing as part of a larger Linux pipeline. To that end, we provide a convenience tool to be used as part of a pipeline. To produce the same output but while emitting valid JSON you can:

$ rosrun royale_ros dump _srv:=/camera/Dump
{
  "Device": {
    "Id": "0005-4804-0050-1916",
    "Name": "PICOFLEXX"
  },
  "Imager": {
    "CurrentUseCase": {
      "ExposureLimits": {
        "57082": [
          "27",
          "2000"
        ]
      },
      "ExposureMode": {
        "57082": "0"
      },
      "FrameRate": "5",
      "MaxFrameRate": "5",
      "Name": "MODE_9_5FPS_2000",
      "NumberOfStreams": "1",
      "Streams": [
        "57082"
      ]
    },
    "MaxSensorHeight": "171",
    "MaxSensorWidth": "224",
    "UseCases": [
      "MODE_9_5FPS_2000",
      "MODE_9_10FPS_1000",
      "MODE_9_15FPS_700",
      "MODE_9_25FPS_450",
      "MODE_5_35FPS_600",
      "MODE_5_45FPS_500",
      "MODE_MIXED_30_5",
      "MODE_MIXED_50_5"
    ]
  }
}

This can now very easily be used in a pipeline. For example, you could copy the parameters from one running camera into another running camera by piping this output into the Config service of another running camera instance. For exemplary purposes, we will show a simple example of extracting the valid use cases you can set on the camera -- (yes, we know, you can easily see them above, however, this is here to show you the intent of processing these JSON data as part of a larger pipeline or to be used in scripts that manage fleets of robots or fleets of cameras on a single robot or fleets of cameras distributed over a fleet of robots -- you get the point).

$ rosrun royale_ros dump _srv:=/camera/Dump | jq .Imager.UseCases
[
  "MODE_9_5FPS_2000",
  "MODE_9_10FPS_1000",
  "MODE_9_15FPS_700",
  "MODE_9_25FPS_450",
  "MODE_5_35FPS_600",
  "MODE_5_45FPS_500",
  "MODE_MIXED_30_5",
  "MODE_MIXED_50_5"
]

The Config service

To change camera/imager parameters, the Config service is used. The Config service accepts the exact same JSON that the Dump service emits, however, it interprets that JSON as a desired state for the camera. Said another way, this allows for declaratively mutating camera parameters. We also note that the whole JSON encoding need not be specified (we will exploit this in the example below).

NOTE: Since this library currently only supports Level 1 access as defined by the Royale SDK, the parameters that the Config service can mutate are limited. Specifically, as of this writing, only the CurrentUseCase and ExposureMode can be changed.

For exemplary purposes, we will use the command line to change the current use case on the camera. Let's baseline the camera's current state by inspecting the dump:

$ rosrun royale_ros dump _srv:=/camera/Dump
{
  "Device": {
    "Id": "0005-4804-0050-1916",
    "Name": "PICOFLEXX"
  },
  "Imager": {
    "CurrentUseCase": {
      "ExposureLimits": {
        "57082": [
          "27",
          "2000"
        ]
      },
      "ExposureMode": {
        "57082": "0"
      },
      "FrameRate": "5",
      "MaxFrameRate": "5",
      "Name": "MODE_9_5FPS_2000",
      "NumberOfStreams": "1",
      "Streams": [
        "57082"
      ]
    },
    "MaxSensorHeight": "171",
    "MaxSensorWidth": "224",
    "UseCases": [
      "MODE_9_5FPS_2000",
      "MODE_9_10FPS_1000",
      "MODE_9_15FPS_700",
      "MODE_9_25FPS_450",
      "MODE_5_35FPS_600",
      "MODE_5_45FPS_500",
      "MODE_MIXED_30_5",
      "MODE_MIXED_50_5"
    ]
  }
}

As a first step to changing the use case, let's first discover the current use case that is active on the camera:

$ rosrun royale_ros dump _srv:=/camera/Dump | jq .Imager.CurrentUseCase.Name
"MODE_9_5FPS_2000"

Next, let's see what valid use cases we can set on the camera

$ rosrun royale_ros dump _srv:=/camera/Dump | jq .Imager.UseCases
[
  "MODE_9_5FPS_2000",
  "MODE_9_10FPS_1000",
  "MODE_9_15FPS_700",
  "MODE_9_25FPS_450",
  "MODE_5_35FPS_600",
  "MODE_5_45FPS_500",
  "MODE_MIXED_30_5",
  "MODE_MIXED_50_5"
]

For fun, let's apply one of the mixed mode uses cases to the camera:

$ echo '{"Imager":{"CurrentUseCase":{"Name":"MODE_MIXED_30_5"}}}' | rosrun royale_ros config _srv:=/camera/Config
[ INFO] [1503078647.907152832]: status=0
[ INFO] [1503078647.907353149]: msg=OK

(For clarity, all we needed to do was pipe in a valid JSON snippet to set the new use case on the camera.)

We now check to see that our camera setting did in fact get set on the camera:

$ rosrun royale_ros dump _srv:=/camera/Dump | jq .Imager.CurrentUseCase.Name
"MODE_MIXED_30_5"

And, for completeness, let's look at the whole dump (you will note there are now two streams encoded in the dump):

{
  "Device": {
    "Id": "0005-4804-0050-1916",
    "Name": "PICOFLEXX"
  },
  "Imager": {
    "CurrentUseCase": {
      "ExposureLimits": {
        "57082": [
          "134",
          "300"
        ],
        "57083": [
          "134",
          "1300"
        ]
      },
      "ExposureMode": {
        "57082": "0",
        "57083": "0"
      },
      "FrameRate": "40",
      "MaxFrameRate": "30",
      "Name": "MODE_MIXED_30_5",
      "NumberOfStreams": "2",
      "Streams": [
        "57082",
        "57083"
      ]
    },
    "MaxSensorHeight": "171",
    "MaxSensorWidth": "224",
    "UseCases": [
      "MODE_9_5FPS_2000",
      "MODE_9_10FPS_1000",
      "MODE_9_15FPS_700",
      "MODE_9_25FPS_450",
      "MODE_5_35FPS_600",
      "MODE_5_45FPS_500",
      "MODE_MIXED_30_5",
      "MODE_MIXED_50_5"
    ]
  }
}