Tracking forward motion in large grassy field
Greetings all, I'm attempting to use Syntheyes to track both lateral and forward motion in a larger sized "grassy" field.
First I'll say where I've been successful, and then tell you where it seems to be falling apart. First, as stated, I'm trying to track camera motion that moves forward (about 30 or 40 feet) in a grassy field (actually a currently dried up lake bed). Let's say this clear, grassy area is approximately 100 x 100 feet, with some far objects just beyond this area to the tune of about 35 to 45 feet ... apartment sidings, windows, tree trunks and other stationary objects. There is very short grass (like astroturf) in a good portion of the field, an assortment of patchy dirt areas, and a few rocks, small to medium size, anywhere from 2 or 3 inches in diameter to a foot or so in diameter.
So here's the issue: When I do a relatively smooth pan shot only, I can get the track solid as a rock in Syntheyes, with no artificial tracking markers set out. But when there is forward movement involved, the scale of the forward movement does not "lock," and I get a sliding of my ground plane and object when I proceed to composite in Cinema 4D.
I am wondering, is this more of a Syntheyes issue, a tracking marker issue, OR, is it a scale issue? After using Lightwave forever, I'm fairly new to C4D, as well as to camera tracking and Syntheyes in general. When I import my forward movement track into C4D, my plane and object do seem to be stable. However, they do not "approach" the camera at the correct scale, i.e. the plane and object are not moving towards the camera as quickly as the camera is obviously moving over the ground, and they do not "scale up" quickly enough to match the approach of the camera.
Just how important is it to match units (this may be an immensely dumb noob question I realize) between Syntheyes and C4D? And if this is not the likely issue, do I simply need to throw out some tracking markers? I hope I've been precise in my explanation of the issue. Any help or feedback much appreciated.