hi this is Elizabeth Postol from Boris effects. Recently one user asked on the Forum why does
the nuke tracker exported from the mocha does not work with the screen replacements
correctly and results look wrong. so now I would like to go over why this might happen,
and explain why you may prefer one or another methods of exporting tracking data
So this is our footage where I'm just showing our mocha Instagram page. but let's say we need
to replace that to something else. let's take Boris effects Instagram page as an example. so
I just took a screenshot and now we can use it as a new screen. let's launch Mocha and get started.
First things first, we need to check, what is happening on our screen. There
is a common mistake that beginners make when they try to draw a shape around the phone but
there is actually some animation or video playing on the screen. if this is your case
then you need to draw a shape only around the edges of the phone where nothing is changing.
but in my case this is just a still image so I can draw a shape around the whole screen
now let's set up our surface plane. if you are struggling with trying to find where the screen
is actually ending try to play with brightness and Gamma to make the edge more visible.
I believe it's somewhere around here. now let's tweak all other corners
don't forget to also choose to track perspective. rename our layer to screen and hit track forwards
after the tracking is done we can check how good it is by setting the grid as an insert.
looks good to me. let's turn the grid off and talk about experts in the data to Nuke.
in general there are three types of tracking data that could be exported. the first one on the list
is alembic mesh. we won't be touching this one today because you would never have Alembic for
the screen replacements. but if you would like to learn more there is already a great
tutorial that Martin did and you can easily find that on Boris Effect YouTube channel.
the next one is nuke 7 tracker that exports translation scale and rotation. and the
last one is corner pin let's select this one and hit copy the clipboard
now I can paste the data into nuke and I would also create a backdrop around this
note and name the Mocha corner pin just to stay organized. okay I'll leave it here for
now and jump back into mocha to now copy the nuke 7 tracker and show you the difference.
now I'm pasting the tracker and let's try connecting it to our new screen and to the source.
you should be aware that this type of tracker does not set up to apply any motion to our image
by default. so first we need to go inside the node and manually check what types of
Transformations do we want. on the transformed tab choose match move because that's what we want
If we try to playback you'll see that now we have two problems. the first one is our new
screen is completely in different place. the other one is that we don't have our sheer and
perspective changes. and that's because this is how regular tracker Works in general. it
only can apply translation scale and rotation changes to the image. so what can we do about?
that because the tracker contains data not only for one point but actually for all four
surface Corners we can generate corner pin from it . you need to select all four points
choose the type of corner pin you want to be exported. I prefer the baked one and hit create.
let's connect that to our image and see if that works.
so now we have our shear but screen is still in the wrong place.
that's pretty easy to fix. go inside the null properties and on the from tab click set to input.
and here you have it you insert screen finally match the original one. although this method
works I do not usually use it for screen inserts because it requires too many clicks
and unnecessary steps that could be skipped. let's delete this and see what result we would get if we
would use corner pin that was exported directly from the mocha. we just connect the input to the
node merge that with the source and everything works straight to the Box. no additional steps
is required. but now you may think is the regular tracker option completely useless ? totally no.
let me give you another example with the same shot. so here is the exact same tracker as we
had before but let's say now we want to create some simple call out. I would create text node
connect it all together and enter some text. something like subscribe to our Instagram
okay now we need to choose to what edge of the phone we want to connect the text.
I open the tracker node zoom in a bit and see that this Edge is tracker number four.
now I need to enable only the translate checkbox and only for this point.
don't forget to set match move on the transform tab. close everything and let's see.
our text is linked to the corner and we don't have unnecessary rotation and scale transformations.
we can even try connecting both of these results together
I believe now you have a better understanding of the difference between these two expert options
and found out when it's better to use one over the other. if you learned something new please give us
a like and leave a comment. if you want more of these videos follow the Boris effects YouTube
channel or visit our Forum in case you have any further questions. that's all for me. bye bye