What am I missing here? Tracking question

JBaymoreJBaymore Website User Posts: 335 Enthusiast

I'm having what I am guessing is a bit of a "beginner" issue.

I have a piece of video footage that is a forward facing aerial shot out the front of an aircraft.  Pure landscape moving along.  This will then get laid behind a cockpit windscreen mock-up (via green screen) of a different type of aircraft .  All that part is set up just fine and looks great.

But................

I want to add some elements to the ground that 'track' with the moving scenery as if they were part of the original video shot.  These will "change the location" of the video due to a viewer's associations with them.  I did some one point tracking of an object on the ground by adding a track to the landscape video clip and then tied that to the visual element I wanted to add.  I got an excellent frame-by-frame track solve on that moving object point on the ground in the video segment.......... and used x and y coordinates.........but when viewed with them tied together to supposedly track, the added object does NOT seem to be "attached" to the ground.  It moves around quite un-naturally.

I am guessing this is because the CAMERA is moving here instead of having the point I'm tracking moving and the camera is fixed.  Yes?  / No? 

Suggestions for me please?

best,

........john

Comments

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,444 Enthusiast

    1) with a single point track on ground coming towards you, as the object/text gets nearer to the camera the object/text will not change size and so will appear to shrink in relation to the ground tracking point, which will get larger. You need a two point track. Put the second point on the same horizontal plane as the first and 200+ pixels away to give Hitfilm a chance to spot the  differences fairly accurately. Tick the 'Scale' box when Transforming, ignore 'Rotate'.

    2) Move the Anchor point of your object/text to the bottom left corner and place that on tracked points position. Then any movement and scale will be relative to that point and appear to be tracked correctly.

    Depending on what you are placing on the tracked data, you might also try with the Anchor Point at the centre of the object/text, or in the centre/bottom to get it to look locked-on convincingly.

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast
    edited December 2018

    Thanks... I'll look at all this when I get back to working on the clip in the program.

    I was "faking" the whole scale change issue by keyframing the scale on the added object...and increasing it slightly over the 7 second-ish clip.

    I was using the center as the anchor point.  Never thought of changing that.  Can you explain the why to the lower left business so I can understand the issues better?

    best,

    ...............john

     

     

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,444 Enthusiast

    If you want something to scale out from the centre, then you track a point that's where you want the centre to be - and a second point somewhere else for Hitfilm to calculate the scale change - and you place the Anchor Point at that centre position. All scale will then enlarge uniformly outwards from the centre. If you want it to scale to the right you place the anchor to the left side. Scale Up:Anchor Point at the bottom. Corners: etc.

    As it scales outwards from the Anchor Point, where you place it is important as well as where the Position is.

    Experiment with a simple small plane and put the Anchor and Position in different places to get a feel for it.

    With a Callout it's about where you place the end of the little 'arm'. That would have the Anchor and Position right on the Tracked Point, so everything appears attached and scales away from that point.

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast

    Aha.... thanks.  Now I get the reasons that the anchor point matters in a case like this.  Man... it's complex.  Getting me back to thinking about my perspective training in art school 50 years ago.

    best,

    ...............john

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,326 Ambassador

    Minor note. @Palacono is absolutely correct in moving the anchor point to the bottom for scaling to match up, but I'd go for bottom center rather than bottom left. I don't think it will make a difference in terms of affecting the tracking lock, but bottom center is more intuitive for me when placing objects. Also to clarify, the anchor point needs to be placed on the edge of the useful data. For sake of discussion  let's assume you're tracking in a greenscreen actor, although this applies to any media. The anchor point should line up between the feet of the actor where the soles of the feet hit the ground. If the feet are, say, 20px from the bottom of the layer and the anchor point is actually at the edge of the layer the actor is "floating" and will drift a little. Lining the anchor point up with the sole of the foot is a rock-solid lock to the tracked point.

    Remember that rotation also happens around the anchor point. Not relevant for the current task, but important to know in general.

    I forget if you're Express or Pro (I'll guess Express, otherwise you'd probably have done a mocha track on your aerial footage) but @FilmSensei has a tutorial on using the particle sim to have Star Wars spaceships jump to light speed. Moving the anchor point to the rear of the ships lets them "stretch forward" on the jump by scaling up the models on their Z-axis.

    So, bottom line tip is moving the anchor point can be key to setting up an effect. 

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast

    Thanks for coaching me thru this folks.

    I'm on HF Pro 11. 

    And I did not think of a 'Mocha track'.  Was adding tracking by hitting the + key on the "tracks" option. As I said... likely this problem of mine is all really based upon "newbie" mistakes.  Hum.......... have to try that Mocha option. 

    And even with the 2 point tracking....... I'm still not getting a good "lock" on the ground location for the object.  The tracking points seem to follow the things I track on the video very well, but then the objects seem to "float around" and "jitter".

    The objects in question to get anchored to the ground scenery are off to the left and right of the centerpoint of the screen and also the axis of aircraft travel on the video clip.....so I am THINKING that using a left bottom (on the left) and a right bottom (on the right) for the anchor points will help with the perspective scaling issues.

    They are "incidental" objects that I need to match up, that are not the focus of the shot, but they will transform the scenery in  an important way for the context of the shot. It works without them.  It will work really well with them.

    best,

    .......john

     

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,326 Ambassador

    So, here's the thing about mocha. Mocha is a separate program from Hitfilm launched as a plug in. Any of the excellent tutorials from mocha on camera tracking apply to Hitfilm. Same goes for Object tracking. This only applies to mocha itself....

    Where it gets different is after the track. From mocha you'll export a Composite Shot. That will contain a camera, points for all active mocha layers and a blue plane representing the current layer in mocha (tip: make sure this is the floor plane). You copy the points/camera back to your original comp shot.

    You may see old Hitfilm tutorials where the video is reimported with the comp. Not anymore. Now it's the plane. This is better as the old method creared duplicate clips in the media bin. Just don't let that trip you up. 

    This is still one of the best tracking tutorials for Hitfilm (Hitfilm 2!). Axel shows how to track a camera  then track an object in the scene. In the next part he uses the camera and tracking data to put an energy orb in the dude's hand. 

    This is the old mocha where the video reimported. Just copy/paste the camera and track data where needed.  You'll be fine. 

     

     

  • WhiteCranePhotoWhiteCranePhoto Website User Posts: 909 Enthusiast

    Mocha has a pretty intense learning curve, but it's absolutely worth the time and trouble!

     

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast

    @Triem23,

    I just watched thru that tutorial.  Nice explanations. Thanks.

    "First impressions" in thinking on this has me thinking about my video clip shot and how this tracking situation happens in Mocha.  The video clip shot in question is an aerial  sequence at some altitude.  Camera is tracking basically straight forward into the distance, with normal slight flight buffeting happening. We are flying over a "soft" undulating landscape of thickly snow covered hills and mountains.  Lots of soft curves below and then jagged rocky mountains around and coming at the camera.  (Think of the planet of Hoth here.)  Unfortunately, there is not a "hard flat plane" in sight.  No really flat ground.  No buildings.  

    So I am guessing my problem is compounded in finding "planes" to use as references to track camera movement.  I'm guessing that I'll get a low percentage camera "solve".  But I'll go 'have at it' soon and see what I get and get back to everyone here.

    best,

    ........john

     

     

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast
    edited December 2018

    OK.......... some success.... but yet more "what am I doing wrong now" stuff.  Seemed to be able to track it easily.

    Fed the aerial video clip to Mocha Hitfilm (Pro ver. 11).  Found two areas of relatively flat planar surfaces visible thru the whole clip....... one was a snowfield on the ground on the left side of frame and one was a mountain face in the distance on the right.  Managed to track each of them well.  Then did a camera solve on that...and got 99%.  (I can taste sucess!)

    Then tracked one ground feature on the left side for one of the objects I want to place, and then another one on the right.  Got pretty tight tracking on those two spots too.

    But now my problem is ..............

    How do I get this information back into Hitfilm Pro?  I hit the "export track data" and "export camera Data" buttons.  I also simply exited Mocha Hitfilm..... and went back into Pro expecting it to magically show up somewhere.  But I can't seem to find where the data WENT.  I found the saved exported data files... but when I went to bring them into the media panel... it said 'invalid file type'.

    If I re-hit  the Mocha interface on the video clip in the composite shot I'm building here, I see the same stuff I tracked previously.  So the data is there.

    I need to now "associate" the two object images with the tracked locations from Mocha.  Plus what happens to the camera data?  I don't see an option in Mocha Hitfilm to export the thing as a composite shot as @Triem23 mentions above.

    best,

    ........john

     

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast

    Went on a Hitfilm Tutorial viewing marathon on using Mocha Hitfilm this morning.  Except what is happening in Hitfilm 11 for me and what I see on the tutorials is not the same.

     

    In Mocha Hitfilm... I am getting good tracks.  The issues are when I go back to Hitfilm.

    Went into Hitfilm... and still cannot figure out how /where the tracking data goes from Mocha.  Tried a couple of different "ways" to get this to work.  I can't find any camera or layer data tracks to work with.  I see Mocha on the clip in Hitfilm, and it shows the various parameters under it in "controls"... but nothing shows those tracking layers and their data to then parent the other tracks containing the stuff I want to "anchor" onto.  If I reopen the Mocha effect in the clip in Hitfilm after doing the export tracks and export camera thing, , I can see the masks if I click on the mask box.  So the data remains linked to the clip and is somewhere.

    There is some fundamental aspect that I an still missing.  Help.

    best,

    .................john

     

  • JBaymoreJBaymore Website User Posts: 335 Enthusiast
    edited December 2018

    I figured out one of my issues with finding the data........ trying to 'load camera data' instead of the composite shot.  DOH!  Made sense to ME.

    But I still cannot get a good solve on my landscape footage and get the objects locked down solidly.  Many hours working on this ...and 'close, but no cigar'.  The tracks seem good in Mocha Hitfilm... but when tied back into the video.... not so good.

    There is nothing "flat" anywhere to align the grid to on a tracked point, and little to give dcent vanishipn points for perspective to visualize the planes well..... so I have to really "eyeball" that alignment.   I'm guessing that is part of the issue. 

    I get close... but the objects still tend to "jitter" around unnaturally on the surface.  Nothiong like the nice steady energy ball in the above tutorial.

    best,

    .......................john

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