I've been (practicing > messing around) with various timewarp modes from 'Duplicated Field' to 'Fluidmotion' over the past week and have become intrigued by the tab next to the fluidmotion setting. Clicking the tab introduces a range of options that presents more questions than I can find answers for. I guess these fluidmotion options may be there to help in the removal of artifacts, that can occur, due to using fluidmotion in scenes featuring detailed backgrounds. These artifacts can be seen in this YouTube video.

https://www.youtube.com/watch?v=KJFKHhlv27s

I'm guessing, that as some of the controls look similar to those available in effects like the paint effect, the aim would be to mask, paint over or minimise the areas with the artifacts.

A quick search of this site comes up with these posts but they don't really address my curiousity.

http://community.avid.com/search/SearchResults.aspx?q=fluidmotion+effect

Are there any details on how and in what circumstances these additional fluidmotion tools could be used?

Edit Ah, ok this looks promising.

http://difanet.jamu.cz/az/vyuka/vyuka_Avid/ostatni_zdroje/AvidMedoaComposer/MediaComposer4/MediaComposerHelp/MotionFX39.html

 http://difanet.jamu.cz/az/vyuka/vyuka_Avid/ostatni_zdroje/AvidMedoaComposer/MediaComposer4/MediaComposerHelp/MotionFX45.html

Thanks for supplying those MC4 links -- always been a mystery.

I eventually came to the same conclusion as others. It is easier to create a duplicate sequence above to cover any artifacts that might occur, than to use the extra Fluidmotion settings to isolate problem areas. That's not to say that the feature couldn't be useful in certain instances...beyond all available knowledge.

I readed the thread but i the post about fixing fluidmotion artifacts is a little bit confusing for me...

Any video for seeing in action? i like to test it :)

I will have a look but this one demonstrates the principle. It's quite old by the look of it and it's a colour change instead of a motion change but the princple is the same.

https://www.youtube.com/watch?v=HEVGhfT2vnc#t=3.2574667

Duplicate the clip, change the motion render type, in the duplicate clip, to something that doesn't produce the artifacts in the problem areas of the original. Then replace those areas by the same method as he is using for the colour change. That should give you the beautiful motion on your main subject, combined with areas that may not look as good as the fluidmotion but don't have the artifacts. You may need to produce a fluidmotion clip with artifacts before you can see the benefits. Movement over a regular patterned background should do it.