Tracker: Bug or feature?

Juda1
Juda1 Posts: 299 Just Starting Out*

I Need to get the x-movement of an object on screen. So I use the Point Tracker to track it and transform that data to a Point layer. On transform I only choose X-Position. BUT: The Point Tracker does X and Y movement!

When only choosing X-Position I would expect that only X-Movement is transformed to the Point layer. So where does that Y come from? Is the X-Movement also transformed to Y-movement or is it, as I would expect, a bug?

Comments

  • Palacono
    Palacono Posts: 3,423 Enthusiast
    edited January 2019

    Oh, that's a bug alright. Goes back a long way too. Just tested in HF2017 to see if it's been introduced recently, but it's there and in the latest version as well.

    The Y coordinate went up to  -2147483648.0, which is quite a long way from 0.

    Report it to https://fxhome.com/support  (I have too, but can't hurt to double up)

  • CedricBonnier
    CedricBonnier Posts: 1,204 Staff

    @Juda1 @Palacono we couldn't reproduce this issue here, would you have any projects & media showing the behaviour you describe? Thanks

  • Palacono
    Palacono Posts: 3,423 Enthusiast

    @CedricBonnier I'm away for a week, but can do when I get back. Occured first time on 4K in latest version and again on 1080p in HF2017.  @Juda can hopefully confirm sooner, though.

  • Juda1
    Juda1 Posts: 299 Just Starting Out*
    edited January 2019

    @CedricBonnier: It happens, when the tracked footage has an y.value other than 0.

    To reproduce it: Make a new Project, add a comp and make it 15 sec. Add a black plane as background. add a white plane as object, add polar warp to the white one and make it a small Point. Animate it to move from lower left to upper Right Corner and render that out.

    Now Import that footage and track ist so you have a solid, simple and constant track. Add a point layer, transform x to it and it will work as expected.

    BUT: Now Change the y-value of the source footage. The x is still same, but if you transform it the transformed point will "walk" up. Since tracking is done to the layer and the tracker is only visible in layer view, not edit view, I would not expect that the transformed y coordinates influence the target point to which the tracking data is transfered to. And most important: If it would influence it (maybe that makes sense to you) I would never expect the target point to walk up. 

    Let's say the tracked footage has an Offset of 10 on Y. It would be okay if the target point also gets this value. But for every tracking point this value is added to the point - thats why it is walking. I would never expect that and so I consider it is a bug.

    Link to example project

  • CleverTagline
    CleverTagline Posts: 3,327 Ambassador

    @Juda1@CedricBonnierI was able to reproduce this issue. Here are the steps I followed, just to provide additional perspective:

    • Created the moving dot footage as described above, imported it, and brought it into a new composite shot.
    • Tracked the dot and applied the track to a point layer, choosing only X-Position when applying. The point layer moves horizontally across the frame, matching the dot's X movement.
    • Changed the Y position of the dot source layer to 10.
    • Deleted all keyframes on the point layer
    • Went back into the track, and re-applied the same tracking data to the point.
    • The point's X motion is the same as before, but it now starts with a Y value of 10, and that Y value increases by 10 on every frame.
  • DannyDev
    DannyDev Staff Posts: 337 Staff

    @CleverTagline

    Thank you for the detailed reproduction steps; it makes our job a lot easier.

    I will be looking into this for a future update. It's too late to be scheduled for HF 12 I'm afraid.

  • Juda1
    Juda1 Posts: 299 Just Starting Out*

    @CleverTagline Thanks Justing for straighten that out. I thought I said the same but english is not my native tongue. Your lists sounds better, so are your Videos :) But I am working on it :D

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