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Thread: COLLADA 1.5 Camera Orientation

  1. #1

    Question COLLADA 1.5 Camera Orientation


    I came here from:

    But COLLADA 1.5 says:
    The camera is defined such that the local +X axis is to the right, the lens looks towards the local -Z axis, and the top of the camera is aligned with the local +Y axis (also see the <lookat> element). This orientation is affected by the <asset> elementís <up_axis> value.

    I'm confused a bit, camera element has it's own asset element and there is a global <asset> too.
    Does camera element/orientation inherit the global (document) or any parent <asset><up_axis> if <camera> doesnt have one?

  2. #2
    Senior Member
    Join Date
    Mar 2016
    The orientation of nested assets overrides those of the parent. They are not in terms of the parent's parameters. This is covered first thing in <asset> section of the 1.5 PDF specification. That's the first place you should look for semantics.

  3. #3
    Thanks, now I see the statement:

    In the case of hierarchical <asset> elements, where both the parent and child assets supply a value for the same metadata, such as for <unit>, the child assetís value supersedes the parentís value within the scope of the child element. This applies recursively.

    But if camera always loking toward -Z (
    then, Does <up_axis> meaningful for <camera>? There are lookat and other transform elements in <node> which are define camera orientation/rotation

  4. #4
    Senior Member
    Join Date
    Mar 2016
    I don't know. I don't have any real experience with the semantics. If there was good software that implements COLLADA you could see what they do. These things can get very complicated.

    The <up_axis> is mainly for numbers inside the element. So if <lookat> is inside the <camera> then it's in terms of the camera. It's for if you link to a document that uses different conventions.

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