Hey Ronald,
 
It has been a while since I have posted queries here.  
 
My question is about survey data and elastics. I have brushing up on my matchmoving and get pretty good results considering i am using 720x576 interlaced footage.  
 
My 2D tracks are solid. But when I give points survey  data or those same points elastic contraints. Those points go yellow and more of them red once i solve the camera. I have never managed to get green tracks.
 
My second question is when ever a tracked point leaves the footage or is obscured the camera jerks enough to make the track unusable. When all of the survey points or elastics are on screen for the entire length of the track then there is no problem at all. In fact tracking is very easy.
 
In some cases i have 15 tracks with survey data/elastics but when one leaves the footage the camera jerks and once the track comes back on the screen the camera jerks back to the correct postion.  
 
Should i be using END key frames for tracks that leave the footage or should they be intermediate keys? And the same question applies for obscurred tracks.  
 
Once I figure this simple problem I would enjoy writing a tutorial on the subject as there seems to be few people who have.
 
Thanks In advance  
 
Michael

Hello !
 
Elastics are really strong constraints (as it fix the 3D coordinates of your track). Therefore it's not unusual to have poorer score for the 3D residual because the corresponding 2D tracks are always a little noisy. But the final result should be exactly adjusted.
 
About tracks that get out of frame, you have several solution to handle this. Setting 2D key type will have no effect on the 3D solve.
Either you just filter the computed camera path in the graph editor.
Or you interpolate the 2D track when the track disappear, to keep it smooth. To do so, just select the frame range and use "2D Tracking / Interpolate Track". This will fill the holes, even if the track gets out of frame.  
 
Once you have some solid manual 2D tracks, do not hesitate to launch an automatic tracking that will generally smooth the camera path.