Litchi - Interpolate and POI Altitude settings

Jester1964 · Jul 22, 2016

Hi all, I've been using Litchi now for a couple of weeks, mainly for the FPV to use with my BlitzWolf VR goggles and phone.

Lat night I tried a mission using POI's with the camera tracking the POI while flying past etc, which seemed to go really well. The only parts I'm not sure about is what 'interpolate' does and how high to set the altitude of the POI. I think the default POI for the mission below might have been 1 - 3 metres

The missions a bit boring but you can speed it up X2 in Youtube, it's a old Nobel explosives site in Stevenston in West Scotland.

TIA

Tim Pearson · Jul 22, 2016

To answer your interpolate question...

Interpolate must be set on two adjacent waypoints in Litchi. You also set the gimbal pitch manually on both waypoints. Then as the aircraft passes through the first waypoint, the gimbal pitch is set to the "starting" value. As the aircraft continues to fly, the pitch slowly changes... until at the second waypoint, the pitch has completely transitioned to the value shown in the second waypoint setup page. This makes the camera angle smoothly change from one setting to the other as the aircraft flies from one waypoint to the other. Again, be sure to set BOTH adjacent waypoints to "interpolate" to make this work correctly. You can have many adjacent waypoints set to "Interpolate" and the gimbal angles will smoothly transition through them all as the aircraft flys from waypoint to waypoint.

Jester1964 · Jul 23, 2016

Cheers Tim, that's a great explanation. So basically, it's a good thing to use when filming the sort on mission I posted? Are there any minus point to using it over just plain 'focus on POI'?

Thanks

Tim Pearson · Jul 24, 2016

My goal is to always avoid rapid movements (even little bitty ones) - in direction/yaw/rotation, forward speed, altitude, or camera angle. If they can't be avoided (or if I can't tweak my mission and re-fly it for some reason), I'll whack out the part of the flight where the rapid movement happens and insert a fade transition in post production. I make sure to remove enough before and after the "too fast" part so there will be a noticeable difference in scenery as the fade transition occurs. That way, the viewer doesn't go "that next scene looks just the same - why did the scene change?"

There were two places in your video where the aircraft really transitioned too fast (I think)... Both were in "heading" (the way the camera was pointing).. the one right at the beginning, and the first course change after that. The first one was probably just your mission engaging and can't really be avoided... I'd just whack that first couple of seconds out. The second was probably your first "focus on POI" waypoint??.... which was quite a ways off to the right from the aircraft's current course. I'd re-do that part of the flight to add a couple more waypoints to get the aircraft to do a curved turn toward the first POI before it hit the one with the "focus on POI" turned on. I couldn't tell if that was what happened for sure... but I did notice the really fast rotation in the shot.

Much less noticeable for most folks were a couple of "robot like" (think Michael Jackson imitating a robots movements) changes where the camera would be going in one direction very slowly and instantly change to going in another direction - also very slowly (which is good)... it was that instant change in direction that caught my eye. I'd let things drift (no focus point) for just a few feet before focusing on the next POI... that way you see one movement stop.... a pause in all the changes where the aircraft just drifts along... and then the other movement begins. "Buttery smooth" is always the goal.

Tim Pearson · Jul 24, 2016

... also, that was some fascinating terrain you were flying over! Old explosive magazines? Bunkers? Just curious... it was really stark and "Mad Max" looking!

Jester1964 · Jul 24, 2016

Wow some great information there Tim, will take a while to digest all that but so many great tips!!

I'm not sure as I've altered the mission since, but I think I had not grasped interpolate at the time, I'll look at the mission video again and try to work through what you've posted.

I've attached a few links re the area. So far I'm one of only a few in our club to fly the area with a drone. My intention is to map the area, but time...................

Much appreciated as always!!

John

Secret Scotland - ICI Ardeer

Nobel Enterprises - Wikipedia, the free encyclopedia

Jester1964 · Jul 24, 2016

I also misjudged my starting point when creating the mission at home, and as you can see at the end after the last waypoint I never adjusted the gimbal setting hence a nice view of the grass lol!! I also never gave myself enough room to frame the POI's.

As said, a work in progress, the site is 10 times the size on the video, so lots to explore, hopefully all with one LONG flight which might not be possible. I will soon find out

Jester1964 · Jul 24, 2016

Yes just watched it again. And you are bang on. And a bit underexposed, although I thought
it looked like the game 'Stalker' lol.

There is some issue with POI's and curved waypoints I had, not sure but I think the fast transition was not a curved waypoint. Do waypoints focused as a POI still work on a curve? Does interpolate address this? This app has a lot of meat on the bones Tim once you start using it!

Tim Pearson · Jul 24, 2016

Wow John, it is truly a small world... I live just 8 miles from the Dyno Nobel plant. One of the last dynomite manufacturers in the USA. I've actually responded to a fire call there. You know you're doing something wrong when you're racing in one direction - passing people in hard hats and white coveralls running in the other direction and pointing over their shoulders.

Anyway, so interesting that we both live near Nobel facilities - albeit a lot different in their ages!

Jester1964 · Jul 24, 2016

lol yes it sometimes is a truly amazingly small world Tim. I love these sort of 'unexpected instances' where people connect, it's definitely an exploratory mindset that led me to DJI and hence Litchi. My head is awash with the potential lol

Oh and I have built from scratch my own Pixhawk S500, a great quad, but very much a work in progress to match the P4 etc as a flying camera platform

Now, CONNEX, would be good but a bit pricy atm

Les Davidson · Jan 7, 2017

To find correct angle click on POI first then interpolate. The correct angle will be set.

Sent from my SM-G935F using PhantomPilots mobile app

AuldGimpy · Jan 14, 2017

Hi John, liked the Ardeer/Nobel movie. I'm a P3/4k ~ P3Pro novice from Sunny Johnstone. What is the club you mentioned? Is it a model aircraft flying and/ or Phantom as well?

Is there 'reasonable' access to the Stevenston Site and do you have any ideas on the best access point? I suppose it will have a couple of the usual 2~ton blocks across the roads to prevent vehicle access. It looks similar to the old Bishopton Nitro/Explosives Site (just west of the Erskine Bridge) and I'm hoping to get a flight or two over it once the days lengthen a bit.

I've had a couple of flights around the deserted IBM Factory at Spango Valley, easy to get to and plenty space to fly around. I knew recognized the place .. I had a job interview there nearly 40 years ago.

Say hello if we come across each other. My cousin is also interested in the Stevenston site. He's a flier, racers and a 'new' Tarot hexacopter being pre-flighted.

Alan.

Osmosis · Jun 23, 2017

Ever notice how sometimes Litchi looses track - even with interoperate on between all waypoints and focus on a single POI?

Check the following video out and you can see several places where the video jumps during turns. Anyone know what causes this?