Hi everyone…
I am following this tutorial for blob tracking. I am able to get the rectangular flickering blobs as of now but I am not able to displace the content inside them as seen in the tutorial.
I have followed all the steps till 15 min 15 seconds.
Can anyone help in identifying what am I doing wrong?
Here’s a screenrecording of what I’m facing.
Blob_Morphing_Shifting_Pixels_forum.toe (626.5 KB)
Hi @swooshycloud,
this is mostly due to how your camera is setup. It’s basically not seeing the geometry you are rendering.
Looking at the tutorial and your file you can simplify things a bit and instead of adjusting the camera manually, set it to have values that will work with any input resolution video.
First, consider that the u, v, width, and height channels are normalized - resolution independent - between 0 and 1. So it would be important to setup the Camera and rectangle SOP to reflect the size and aspect ratio.
To do this it’s probably best to use a fresh camera. Go to the View parameter page and set the Projection parameter to “Orthographic”, the Ortho Origin parameter to “Bottom-Left”, and the Ortho Width parameter to the size of your input video - a reference to the Info CHOP’s “resx” channel would work well here.
The selected value for the Ortho Origin is because of our u and v channels going from 0 to 1 so their minimum value is 0,0 - Bottom Left. By default the camera though is setup to look straight at 0,0 - it would be in the center…
Lastly change the Scale parameter on the Geometry COMP’s “Xform” page to match the video size - again with a reference to the Info CHOP’s xres and yres channels. This will make sure that our instancing setup which receives all normalized values, is scaled to the input videos resolution and size.
If you now use a Over TOP to place the rendered image over the image from the Blobtrack TOP, you can see that the rectangles drawn by the Blobtrack perfectly align with the rectangles rendered from your instancing setup.
A slight note for simplifying things:
Instancing can be driven by TOPs, CHOPs, and DATs - so you can use the Info DAT which shows the blobs directly as source for the instancing instead of converting from DAT to CHOP to TOP.
Attached is the simplified and working file.
Hope this helps
cheers
Markus
Blob_Morphing_Shifting_Pixels_forum.1.toe (625.4 KB)
