Re: [mediacapture-image] Add pan and tilt constraints

> That sensor has max 1 degree rotation. Lets say, with 50-60 deg FOV for webcam, that would not be much of a pan / tilt.

Webcams I've dealt with that were providing electronic pan tilt were in the range of +10 to -10 degrees.

> @dsanders11 Do you think pan / tilt rotations need to be with less than 1 degree steps? Can long be used instead of double?

I think it needs support for less than 1 degree steps because there's nothing that says it can't be less than 1 degree. While in practice it may be uncommon, how would the API act if there is a camera with 0.5 degree steps? I suppose this spec could round step to the nearest degree, but that could again run into a camera that has something like 0.75 degree step which would mean a rounded degree value is often not a valid value.

The underlying APIs that are used for the camera control (UVC and Windows [getRange_Pan](https://msdn.microsoft.com/en-us/library/windows/desktop/dd376305(v=vs.85).aspx)) return the step value as arc degrees so I think we have to assume that it can be less than 1 degree.

>  BTW, did you check my question about pan tilt roll order? I still think it is important, that is why it is PanTilt or PanTiltRoll, standard Euler angles rotation order (ZYX, yaw-pitch-roll)

You'll have to make an example of how to accommodate this in the spec, I don't see how enforcing an order can easily be added to the current API.

Wouldn't order only matter if using relative pan tilt roll? So far everything in the spec (correct me if I'm wrong) is using *absolute* values for constraints, not *relative* values. While order certainly matters when making relative transformations, does it matter when the values are absolute? Doing pan 5 degrees, roll 5 degrees, pan -5 degrees, roll -5 degrees would not get you back to default position when using relative values, doing pan to 5 degrees, roll to 5 degrees, pan to 0 degrees, roll to 0 degrees will always get you back to default position since they're absolute and the last value set was 0.

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Received on Monday, 19 June 2017 20:17:31 UTC