how do you acquire good elevation

[George R C]

Hey Guys
the p4p is ok for stitching maps but what drone is great for acquiring elevation from trees without using lidar? Anyone have any suggestions ?

 

[Shoot4fun]

What type of "elevation" do you mean?

 

[Shoot4fun]

Ar you having issues flying around trees? If so, turn your sensors off. Just be careful!

 

[George R C]

sorry.. I mean acquiring tree heights ...

 

[Shoot4fun]

Ah! Gotcha. I got nothin for ya then... ?

 

[Fly Dawg]

Anyone have any suggestions ?

The only thing I would suggest is dream on for a while. It does not exhist. Terrain, yes. Other inanimate objects No. These aircraft will only know there is something in the way after it is almost too late.

 

[Weston Ney]

Hey Guys
the p4p is ok for stitching maps but what drone is great for acquiring elevation from trees without using lidar? Anyone have any suggestions ?

If you want to find the approximate height of an individual tree you could try taking off from the ground and flying to the top of the tree and center your camera on it to see approximate elevation, but using this method would take a while to measure a whole forest![emoji2957] how accurate do you need to be?

 

[solentlife]

Funny guy should ask ...

I have a lot of trees in my grounds and one in particular - a massive 'Chrstmas Tree' - I have always wanted to decorate for Christmas. I needed to know its height.

So similar to Weston Ney suggested - I powered up and flew to top ... just read of the altitude on screen ... OK - so its based on barometer and will not be super accurate - but what amazed me was how close the figures worked out when I compared to shadow calculation.

For those interested ... the shadow calculation is quite simple.

Its a right angle triangle to ascertain the height of an object (not the length ... as that entails any angle the item may be from vertical).

The sun casts a shadow of the tree and you peg the end of the shadow, to mark it. You then stand on that mark and measure the angle of base to top of the tree. I use a sextant - yes I'm from the old school navigators !! But a variable set square can do it.
You now have this angle, plus the 90 at base ... you then know the third angle ... and the base length.

You can now use schoolboy trig to calculate the height.

As I say - the calculation was amazingly close to the reading on my tablet from the DJI barometer.

Note in fact - you need not take off directly at base of the tree. You can power up ... have everything displayed, pick up by hand your drone ... walk to tree, place at base and read of the numbers. Pick it up and back off to safe take off place ... fly up to level with top of tree (using video to sight obviously with camera at 90 ...) read numbers. Difference is height.

Maybe I'll do a demo vid ...

 

[Weston Ney]

Funny guy should ask ...

I have a lot of trees in my grounds and one in particular - a massive 'Chrstmas Tree' - I have always wanted to decorate for Christmas. I needed to know its height.

So similar to Weston Ney suggested - I powered up and flew to top ... just read of the altitude on screen ... OK - so its based on barometer and will not be super accurate - but what amazed me was how close the figures worked out when I compared to shadow calculation.

For those interested ... the shadow calculation is quite simple.

Its a right angle triangle to ascertain the height of an object (not the length ... as that entails any angle the item may be from vertical).

The sun casts a shadow of the tree and you peg the end of the shadow, to mark it. You then stand on that mark and measure the angle of base to top of the tree. I use a sextant - yes I'm from the old school navigators !! But a variable set square can do it.
You now have this angle, plus the 90 at base ... you then know the third angle ... and the base length.

You can now use schoolboy trig to calculate the height.

As I say - the calculation was amazingly close to the reading on my tablet from the DJI barometer.

Note in fact - you need not take off directly at base of the tree. You can power up ... have everything displayed, pick up by hand your drone ... walk to tree, place at base and read of the numbers. Pick it up and back off to safe take off place ... fly up to level with top of tree (using video to sight obviously with camera at 90 ...) read numbers. Difference is height.

Maybe I'll do a demo vid ...

another thing you can do if you only need to know the measure of one tree, is measure the tree with the drone once, land, restart the drone, and do it again. Repeat three or four times, and take the mean average of the measurements. That might get you a more exact reading, and if one of your measurements is completely off, you will have other measurement data to keep you on the right path.

 

[solentlife]

another thing you can do if you only need to know the measure of one tree, is measure the tree with the drone once, land, restart the drone, and do it again. Repeat three or four times, and take the mean average of the measurements. That might get you a more exact reading, and if one of your measurements is completely off, you will have other measurement data to keep you on the right path.

Correct. Its actually an Accepted Approach to any test ... repeated tests to arrive at mean average result.

In my business - we have two factors that govern reported results of tests :

Reproducibility

Repeatability

 

[Propsontop]

Hmmm....angle of the dangle divided by the inner diameter slope with "schoolboy trig" calculated for the sun's morning azimuth times the rotational speed of the earth....
Yup! It's a tall tree all right!

 

[solentlife]

Light hearted diversion now after post #11 ..

A question was posed in one of the Navigation Classes I was in ... its actually one that was doing the rounds of various but the Lecturer decided it was good for us !!

You are somewhere out in Sahara Desert and its June 21 ... you have a set of log tables, ruler, watch set at GMT and a calculator.
You know the position of a town but have no idea which direction ...

How do you determine your position and which way to move ?

 

[Weston Ney]

Light hearted diversion now after post #11 ..

A question was posed in one of the Navigation Classes I was in ... its actually one that was doing the rounds of various but the Lecturer decided it was good for us !!

You are somewhere out in Sahara Desert and its June 21 ... you have a set of log tables, ruler, watch set at GMT and a calculator.
You know the position of a town but have no idea which direction ...

How do you determine your position and which way to move ?

If you are ever in this situation then you should be rethinking your life choices.

 

[solentlife]

If you are ever in this situation then you should be rethinking your life choices.

Agreed ... but the idea of the question to us Navigators was whether we could work out the answer using fundamental principles.

I was just reminded about it when positing about ways to measure tree height. The principles are basically same.

 

[KachemakDiver]

Fall the tree then get your trusty tape measure!
Just kidding. I would go with Weston Ney’s solution.

 

[grego122]

Get some paracord pull it up to tree top mark cord then measure might get you the height
maybe not the most accurate but close good luck!

 

[Deleted member 120647]

If you have line of sight.