What needs adjustment here?

[G Randy Brown]

I went to my bigass parking lot practice area this morning and wanted to measure how high the lights were to set my RTH altitude accordingly.
I got about 10' away from one and ascended slowly to measure it and according to my screen info it's 8 feet tall (it's over 75' using my eyeball').
Also the RTH missed by a good 10'....what would you do to try to correct this?
Missing 10' with RTH is not a big deal as I can correct that but it seems altitude could be a big deal.
Thanks,
Randy

 

[GoinPostal]

I went to my bigass parking lot practice area this morning and wanted to measure how high the lights were to set my RTH altitude accordingly.
I got about 10' away from one and ascended slowly to measure it and according to my screen info it's 8 feet tall (it's over 75' using my eyeball').
Also the RTH missed by a good 10'....what would you do to try to correct this?
Missing 10' with RTH is not a big deal as I can correct that but it seems altitude could be a big deal.
Thanks,
Randy

My experience would say, upon takeoff hover for a minute or two, to get a good GPS/RTH position before proceeding. If that doesn't work calibrate the vision sensor. That's all I got, hope it helps

 

[Meta4]

I went to my bigass parking lot practice area this morning and wanted to measure how high the lights were to set my RTH altitude accordingly.
I got about 10' away from one and ascended slowly to measure it and according to my screen info it's 8 feet tall (it's over 75' using my eyeball').
Also the RTH missed by a good 10'....what would you do to try to correct this?

If you launched from close to the same level as the base of the lights, your altitude should be pretty close.
Can you confirm that the light base is about the same altitude as the launch point?
If it wasn't, that's possibly your problem.
If it was, start all over again.
Watch the height as you climb.

My experience would say, upon takeoff hover for a minute or two, to get a good GPS/RTH position before proceeding.
If that doesn't work calibrate the vision sensor. That's all I got, hope it helps

Neither GPS nor home point recording, nor VPS sensors have any influence on the zero reference height or the barometric sensor.

 

[GoinPostal]

If you launched from close to the same level as the base of the lights, your altitude should be pretty close.
Can you confirm that the light base is about the same altitude as the launch point?
If it wasn't, that's possibly your problem.
If it was, start all over again.
Watch the height as you climb.

Neither GPS nor home point recording, nor VPS sensors have any influence on the zero reference height or the barometric sensor.

Ok,
I'll be watching to see the solution

 

[G Randy Brown]

The way I take off now (after seeing videos stating it's the best, most accurate way to set the home point) is if the take off button is responsive (sometimes it isn't and I take off manually) I let it hover for a few seconds and then slowly ascend to around 23 feet and hover for several more seconds.
I've never heard anyone suggest hovering for "a minute or two"...is that really necessary?
Next time I fly I will pay attention to the altitude displayed (I was just eyeballing 23 feet).
Thanks for your help guys,
Randy

 

[G Randy Brown]

If you launched from close to the same level as the base of the lights, your altitude should be pretty close.
Can you confirm that the light base is about the same altitude as the launch point?

Well it is a parking lot so I would think the altitudes are within a couple of inches of each other.
I look forward to the day that we will be able to ping to the ground surface to know the altitude above the surface we are flying over (if I live that long ? ).
The other day I was flying about 20 feet above the home point toward a mesa and freaked out when my obstacle avoidance (thankfully) went off.

 

[G Randy Brown]

This will demonstrate the altitude difference between the light and me.

 

[Dave Maine]

Note that the altitude information comes from the altimeter, not the gps. As such, it is dependent on variations in air pressure. In general, it is not particularly accurate or repeatable. Use caution with whatever values you get.

 

[jlatas]

Note that the altitude information comes from the altimeter, not the gps. As such, it is dependent on variations in air pressure. In general, it is not particularly accurate or repeatable. Use caution with whatever values you get.

But the barometric altitude sensor should be alot more accurate than the original poster stated...most likely +/- 1meter...

The altitude is referenced to the takeoff level, so if you take off at the top of a hill and descend down into a valley the altitude will be negative.

 

[jlatas]

The way I take off now (after seeing videos stating it's the best, most accurate way to set the home point) is if the take off button is responsive (sometimes it isn't and I take off manually) I let it hover for a few seconds and then slowly ascend to around 23 feet and hover for several more seconds.
I've never heard anyone suggest hovering for "a minute or two"...is that really necessary?
Next time I fly I will pay attention to the altitude displayed (I was just eyeballing 23 feet).
Thanks for your help guys,
Randy

I lift off to where the drone sits at about 4 feet until I hear the voice prompt letting me know the home point has been noted, typically a few seconds. I then make sure I have a good number of GPS satellites and then I fly.

I usually leave my RTH altitude set to 200ft and adjust as needed