For those who are interested...
Today, I had a little bit of a scare while using Active Track to follow a fast moving object upwards on a slope. I knew that Obstacle Avoidance is deactivated while using Active Track (or any one of the auto modes), but I thought it would still maintain its height relative to the ground. Well, I thought wrong, since my Spark flew straight into the ground. Apparently, it ignores input from its downward sensor/camera. Fortunately though, it landed on thick grass, and it isn't damaged at all, I've done a couple of flights after that.

Yes, it doesn't seem to like the ground to slope at all.  I was filming my kids sledding last weekend, and I don't know if my eyes were playing tricks on me or if the Spark just didn't know where it was, but it seemed to lose altitude when flying in any direction.  I imagine the auto modes would have been a nightmare under these conditions.

That is why I think a pilot needs to be flying (or ready to fly) the drone even when it is doing its intelligent modes.  A pilot needs to be monitoring the aircraft at all times.  You can't be the subject and be ignoring the drone, as you perform your activity, while it does it's thing.  The Spark's AI flying the drone is not very bright and will rapidly get into trouble.

Worst, I think Active Track only uses the subject image's position in the video to control the Spark's position, which leads to the Spark sliding off into the distance or into things, instead of hovering stabily.  

Active track:

page 18 in the manual: the aircraft will automatically avoid obstacles in its flight path. but NOT able to avoid obstacles in Profile mode.
page 19: says to be vigilant when the subject is NOT moving on a level surface or moving on a snowy surface. there are some other recommendations as well

AC should respond to the sticks movements while in Active Track though

Bottom line is it doesn't have a radio altimeter...if in Active Track and going downhill your drone will maintain it's altitude, follow the subject, but the subject will get farther and farther away...and vice versa if subject is going uphill...it will hold altitude until it runs into the slope.

RobertWSimpson Posted at 2018-2-28 10:11
Yes, it doesn't seem to like the ground to slope at all.  I was filming my kids sledding last weekend, and I don't know if my eyes were playing tricks on me or if the Spark just didn't know where it was, but it seemed to lose altitude when flying in any direction.  I imagine the auto modes would have been a nightmare under these conditions.

The snow could also have been the reason for its strange behaviour, the Sparks sensors can't function properly over snow because of its homogenous surface and its reflective properties, if I'm not mistaken.

KurtVD Posted at 2018-2-28 13:16
The snow could also have been the reason for its strange behaviour, the Sparks sensors can't function properly over snow because of its homogenous surface and its reflective properties, if I'm not mistaken.

that makes sense.  I've also flown in heavy fog and the sensors freaked out as well.  

KurtVD Posted at 2018-2-28 13:16
The snow could also have been the reason for its strange behaviour, the Sparks sensors can't function properly over snow because of its homogenous surface and its reflective properties, if I'm not mistaken.

Hi, there. Please note that things can have a bad influence on the VPS and I would recommend you fly in recommended environment for your drone's safety.