The final practical task in the VFX unit I have to complete is a 3D tracked shot with an image of a door somewhere in the scene. Since I've already done the previs of my shot, it's time to set to work on the shot.
The first thing I did was open up a new Nuke project, and read in the clip I downloaded from Pexels. I made sure that everything was set to the correct frame rate and format (1080) before doing anything else.
I then added in a frame range node and changed the frame range to 45 to 380, which is the time period in which the cliff face remains uncovered by the pine trees. I made sure to keep a bit of overlap at the beginning in case I decide to roto any of it out as a stretch goal. I then read out the video as .exr files, which should speed up the playback.
However, because the playback was still being slow, I added in a reformat node and reformated the footage to 1080 and wrote it out again. This sped up the playback significantly.
I added in a backdrop node to put the assets in and then added a postage stamp of the footage. I then added in a merge and write node, ready to use for later, as well as a dot to keep things clean in the pipe. Connecting to the dot, I added a camera tracker node, which I hooked up to the viewer.
I set the setting of the tracker to Free Camera and Unknown Lens. Since I didn't film this footage, I have no way of knowing what type of lens a camera has or what the focal length might be. If I was working on tracking this shot in a VFX studio, I would be provided this information by the Data Capture Technician, whose job is to be on-set and record and keep track of things like that.
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Once I'd made sure everything was selected correctly, I clicked track, which prompted Nuke to start tracking the footage. This took a few minutes to complete.
I limited the amount of tracked points to 150, which made the process faster. The next thing I did was look at the error number. Since it's under 1, I didn't have to do anything to fix it. However, I went ahead and deleted all the deleted the rejected and unsolved tracked points, as well as many of the nodes in the sky, which brought the error number down to 0.8.
I had a quick look at the graph, which shows me the maximum amount of errors in the track, and their range. Since it was already below 1 to begin with, there is nothing too severe here.
As I was happy with my track, I selected Scene+.
This created a whole new section of nodes on the node graph, which is where I will be working from next. I also looked at the track in the 3D view, which showed me how oddly spaced out all the nodes were.
To correct this, I had to use something in the environment to give Nuke a sense of scale. I decided on a tree to the far right, which had 2 tracked points partway up its base. I decided that this, based on the length of the overgrown grass, was approximately 160cm. This spread out the nodes to look a little more accurate.
Lastly, I assigned a node to be centered and placed on the origin, which will help me when positioning the image plane in the next post. I chose the top corner of the rock where I hope to place the door, which will mean I will have to rotate it more than I normally would have to. However, I would've needed to rotate it anyway, so this is no loss.
Overall, I feel as though I am doing well with this task. At the beginning of this unit, I had very limited experience and knowledge of how to use Nuke, but now I'm solving problems such as playback issues by myself. This is something I never would've expected, and I hope I can use this new found way of problem solving in any issues I have going forward.
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