Mobile phone screen replacement in HitFilm 4 Pro

larsforseth
larsforseth Posts: 15
edited March 2016 in Post-production techniques

Hi there,

I purchased HitFilm 4 Pro a couple of months ago, but finally found some time to give it a spin. Yesterday I tried almost all day long to replace the screen of the mobile phone in this shot:

http://dissolve.com/products/001-D538-2-021

(I am referring to the section where the girl swipes from top to bottom to scroll)

Unfortunately, I didn't manage! :(
The tutorials from HitFilm and Mocha unfortunately didn't help and other tutorials which are based on AfterEffects seemed so easy, but Mocha and HitFilm seem to behave differently than Mocha with AE.

Did someone here have the same problem and solved? Could someone please give me a hint on how to achieve this?

Many thanks in advance,
Lars.

Comments

  • StephansBilderwelt
    StephansBilderwelt Posts: 521 Just Starting Out*

    Did you try the standard two point tracking? 

  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff

    Can you clarify which part of the process is causing you problems? Since there are a number of steps to the process (block out the hand, track the screen, export the points from mocha, import into HitFilm, then sync the new screen up to the tracking), knowing where you need further help will ensure that we offer relevant suggestions.

  • Thanks for your answers so far! :)


    AxelWilkinson The issue I am having is that I can remove the green mobile screen with a chroma key effect on a grade layer (which has a mask so only the mobile screen gets keyed and not the rest of the shot, like the green leaves on the ground).

    However, when I then put some pictures which I'd like to have the girl scroll through on her mobile, the girl's finger seems to be below the keyed out screen.

    I then tried following this AfterEffects tutorial in HitFilm and Mocha, but when I paste the Mocha tracker data from the clipboard (after having Mocha copy it to the clipboard like shown in the tutorial) into HitFilm, nothing happens and the tracker points do not show up... :-/

    Here's the link to the AfterEffetcs tutorial I am referring to:

    What am I doing wrong?

  • Aladdin4d
    Aladdin4d Posts: 2,481 Enthusiast

    Ok for the first paragraph to make that work what you need to do is create another composite shot and move the pictures you'd like the girl to scroll through to it then add your original keyed composite shot to it as the top layer.

    Second paragraph - This sounds like your picture layer is on top of the other layers so it's obscuring things.

    Third paragraph - Unfortunately you can't copy and paste from Mocha with HitFilm like you can with AE. What you have to do is export a HitFilm composite shot from Mocha then import that into HitFilm.

    Now the cell phone has some movement so you probably want to do some tracking so the pictures move with the phone. You can do this with Mocha or HitFilm's native tracking. Here's a good tutorial on the native tracking.

  • Aladdin4d Thanks a lot for the hints. I'll give it another try then after I watched the tutorial you linked! :)

  • Aladdin4d Many thanks again for the hint with the extra composite shot needed. That did the trick and now the finger stays on top of the keyed out screen! :):):)

  • Aladdin4d
    Aladdin4d Posts: 2,481 Enthusiast

    @larsforseth What you were running into was the processing order for layers and effects. By embedding your original comp in a new one you 'baked in' everything, the grade, the mask and the key, in that comp. In After Effects they'll say precomp and precomping and in HitFilm it's embedding.

    I'm copying and pasting the processing order from another thread because A) I'm lazy and B) That discussion has been going on at the same time as this one. The comment I'm copying is from Triem23, a resident expert on all things HitFilm

    "What works on each layer is inherent in the display of the layers.

    Layers are processed in the timeline in order of bottom-to-top.

    The processing within a layer works from top-to-bottom as displayed in the layer controls. So, if you twirl open an asset layer (Plane, video, image) you'll see things calculate in the following order: MotionTracking>Masks>Effects>Transformations(>Material--3D layers only).

    For 3D models the order is: World Transform(Transformations that effect every model in this layer)>Materials>Models (This is where submodel/animation group transformations happen)>Masks>Effects

    For Grade Layers the order is Transform>Masks>Effects.

    The change of processing order between Grade and Asset layers is why Grades aren't doing what you're wanting the to do, but a Grade Layer HAS TO process in that order."

    http://hitfilm.com/forum/discussion/39821/cant-use-mask-on-grade-layer-over-projection

    This is a link to the manual detailing the render pipeline:

    https://hitfilm.com/reference-manuals/hitfilm-4-pro#the_render_pipeline.htm

    You'll notice it says Grade Layers will flatten all layers below so there are times when you can use a Grade Layer instead of embedding a comp but remember this only affects layers below the Grade not the Grade Layer itself so when you have masks and effects applied to the Grade Layer like you do then you need to embed it to 'bake in' everything.

    Another method for doing what you wanted to do in a single comp would be have a layer with the footage and mask the cell phone on that layer then duplicate it and invert the mask. Create the key on the original layer and make another layer below both of those for the photos. Which way is ultimately better depends entirely on what all else you might be doing. If you know you're going to be doing more then your original approach is probably the way to go but if this is it then this method gets you there a little quicker.

  • larsforseth
    larsforseth Posts: 15
    edited March 2016

    @Aladdin4d Thanks a lot for the detailed explanation. I think I'll just stick with the sub-comp method you proposed earlier as it's easier to grasp imho. As I'm just starting out, I need to get quick results in order to stay motivated and get going... ;)

    My understanding was/is that chroma key is nothing else but a mask, but rather being based on particluar shapes - such as "normal" masks - it's a mask based on a "target" color. So I thought that anything below (in a lower layer) this "target" color will be visible through the "hole" the chroma key creates in the upper (higher layer in layer stack). But I guess I didn't know (and still don't quite grasp) the processing order of masks, effects and layers... :-/

    The link you provided really helps and I will have to re-read this again in a calm moment. From what I understand now, my mistake or let's call it lack of knowledge was this:

    "When using a layer as a source for another effect it is important to understand that the source layer will be used before masks and effects are applied."

     

    So thanks again for taking the time for your in-depth answers. From software development forums I used to participate in, I'm used to a simple "RTFM", but you took the extra  mile to help out a nooby and for that I am grateful and shall return the favour in the future! :)

  • Andy001z
    Andy001z Posts: 3,149 Ambassador

    @Larsforseth have you seen Mocha's own youtube videos on using with Hitfilm? 

  • Stargazer54
    Stargazer54 Posts: 3,425 Ambassador

    Speaking of Mocha, you can also find tutorials on their site:

    http://www.imagineersystems.com/video/?dd=dateNew&tagFilter=Training Videos&orderby=date&order=DESC

    They have a handy "browse by:" drop down and you can sort for beginner tutorials and even by HF specific tutes. 

  • Thanks Stargazer54, I'll have a look! :)