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An example of how to use Find Object

The following steps were used to set up the example in figure 10.82.

Figure 10.82: Timeline; control window and compositor for FindObj

1. For best results, set Play every frame in Settings → Preferences → Playback A.
2. Load 3 tracks of png/jpg files – this is one of the more useful working cases:
   • 1^st track should be the scene; that is the output
   • 2^nd track is the object to find
   • 3^rd track is the replacement object
3. Drag the Find Object plugin onto track #1.
4. On each of other 2 tracks, click the right mouse button; choose attach effect, highlight Find Object in the shared effect column, and click OK. All three tracks should now have a findobj plugin effect bar. One, (probably the first one) is the master plugin and the others are attached input tracks.
5. Check the plugin show icon on the master track to bring up the controls for the FindObj plugin. You will see that Use FLANN is checked for using nearest neighbors.
6. Set Output scene, Object, and Replacement object layers’ track number accordingly (numbered from zero).
7. Check Draw scene border and you will see a white border in the compositor window surrounding the whole image of the scene. This assumes default settings for Scene center X,Y(at 50%), and area W,H (100%). Adjust these however you need to via the dials or more simply by checking Drag and dragging any of the 9 drag points. As shown above this in the controls, units are in 0 - 100%.
8. Turn off Play track in the patchbay on the first track so you can see track #2 in the compositor and then use the Object X,Y,W,H dials. You will see a blue-dotted line which should then be adjusted to surround the desired object. Since it can be a little tedious to use the dials, you will want to turn off the previous Drag box of track #1 and check this instead to do your dragging placement from drag points.
9. Turn off Play track in the patchbay on this track #2 so that track #3 is visible and if necessary, adjust the dials/drag box in the same manner. The border will have a pink-dotted line around it.
10. Turn back on all of the desired Play tracks in the patchbays.
11. Set the detector choice (should have Don’t calculate set initially), for example use SIFT.
12. Turn off all of the Draw borders and whichever Drag box that may still be checked.
13. Check Replace object to see the replacement overlay. At this time you may still want to change the checkboxes of Aspect, Rotate, Scale, and Translate and adjust DX/DY in the Replace column.

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Next: MoveObj, FlowObj, GaborObj, StylizeObj, Up: OpenCV plugins Previous: Description of Find Object   Contents   Index

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