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Motion Tracking


Crackdizzle
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Hi

Here are some simple steps to get you started...

  • Switch into Dual Previews (Options/Display) so you can monitor what is happening on the sequence.
  • Load a clip to VP that has a subject in motion that you want to follow with say, a pointer. In this example I am going to indicate the yellow dingy with an arrow above the mast.
  • aa.jpg
  • I need a pointer ,,,, an arrow....... You may have one already but VP has a good selection of useful clip art.
  • Right click in the clip bin and select Add Images from NCH Clipart Library
  • Navigate to Icons/ Arrows and select Big Bold Arrow...
  • ccc.jpg
  • Click Download and the image is automatically placed in the image bin ready to use. It has a transparent background.
  • Click the arrow thumbnail in the clip bin and then select Rotate 180 deg to make it point downwards.
  • Now drag the arrow from the bin and drop it on Video Track 2 and then extend it to match the length of the clip below..
  • Click the FX box on Track 2 and add a  Scale effect to reduce the arrow to a suitable size. Use the Sequence Preview window to monitor the result.
  • dd.jpg
  • Now add the Position effect
  • Set the effects red cursor line to the start of the clip (left) (see above)
  • Drag the position rectangle around the Clip Preview screen to move  the arrow to the desired place in the main clip  e.g. Over the subject....
  • ff.jpg
  • Add a keyframe to fix the arrow in position in the clip by clicking the small green + sign with the red bar.
  • Move the red cursor line along the the graph and every now and again reset the Position of the arrow on the subject and create a new keyframe.
  • If the subject movement is smooth and in a straight line then fewer key frames will be needed, but if the subject changes direction constantly more keyframes will be required at each point of movement.
  • In this example the movement of the dinghy is pretty smooth from right to left...but in the middle of the clip it tacks and there are more keyframes required to keep the arrow at the tip of the mast... This is reflected in the graph.
  • ee.jpg

Every now and again move the cursor line left to right to check that the marker is correctly following the subject. You can insert more keyframes if tou feel the tie/up is not quite correct. Of course your marker  doesn't have to be an arrow. Any type of marker can be used even normal text characters (like O) or the Censor block from the effects list as Borate has suggested. This can be pixelated to disguise faces or solid to cover up objects...but it will always involve the Position effect coupled with Keyframes.

Hope this helps a little.

Nat

 

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