Virtual Litchi Mission

[joeruby]

Hi D J Wes (and everyone interested),

Yes you said it very well. I am glad that you understood what I was trying to explain. Thank you for your two experiments. They clearly show suttle, but important, difference.

I mostly fly TNW curved turns so I can see where I am going, Thus I expected that the simulation would have the AC and camera point tangent along the actual curved (blue) flight path. Maybe Namirda can make that an option in his fantastic simulation VLM program.
Joe
KC7GHT

 

[namirda]

Hi Joe etal,

I found your comments about aircraft heading versus VLM heading interesting. I have used Litchi for well over two years and I had always experienced that the heading of the aircraft between two waypoints interpolated smoothly between the heading specified at one waypoint to the heading specified for the following waypoint.

I just performed a little test. I flew two missions. Both had the exact same waypoints with the same exact headings. For the first mission I used “TNW” (to next waypoint) as the Heading Mode. For the second mission I used “Custom” (manually setting the heading to point at the next waypoint). When I flew these two missions I saw a different behavior in the heading mode of the drone. In the “Custom” mode, the drone smoothly transitioned from the heading defined at one waypoint to the heading defined at the next waypoint. However, in “TNW” mode, the heading of the drone was always tangent to its flight path. In other words, the drone always pointed forward along the path it was travelling.

I was surprised at this, but in my 2+ years of using Litchi, 90% of my missions used “Custom” waypoint headings (either POI or manually set). I may have only casually tried TNW without really looking closely at the heading of the drone. Therefore, my experience had been that the drone heading always smoothly interpolated between what was defined at each waypoint. Now, I know that the “Heading Mode” changes this behavior.

Namirda can comment on VLM’s implementation, but my experience with VLM suggests that it always has the aircraft heading interpolate smoothly between two waypoints, even when the “Heading Mode” is set to “TNW”.

We had a beautiful calm winters day here in NZ today and so I took the opportunity to repeat your experiment. Like you, I was surprised by result which was the same as yours. The mission is flown completely differently if the Heading Mode is set to Auto/TNW!!! This has obviously not been clear to many of us - particularly those of us that never use this mode!!

The issue for VLM is that the csv file exported from Litchi does not contain the "Heading Mode" and so I will have to make it a user option in Settings.

An update will come in a day or two with this fix as well as the option to use your own Google API key.

Thanks for pointing this out Joe

N

 

[joeruby]

We had a beautiful calm winters day here in NZ today and so I took the opportunity to repeat your experiment. Like you, I was surprised by result which was the same as yours. The mission is flown completely differently if the Heading Mode is set to Auto/TNW!!! This has obviously not been clear to many of us - particularly those of us that never use this mode!!

The issue for VLM is that the csv file exported from Litchi does not contain the "Heading Mode" and so I will have to make it a user option in Settings.

An update will come in a day or two with this fix as well as the option to use your own Google API key.

Thanks for pointing this out Joe

N

Namirda, this FANTASTIC NEWS. I (we) sure appreciate all your effort, knowledge, and talent.
Joe
KC7GHT

 

[namirda]

Virtual Litchi Mission V2.4.0 is now available on Dropbox. As usual, the download link is available on the first post of this long thread.

Changes from V2.3.0 are as follows :

1) Added option to use your own Google API key. You can input your private key in the Google Tab of VLM Setup. If you do not enter a private key, then VLM will use a key which is shared between all users. It is quite likely that this shared key will exceed it's daily limit from time to time - if that happens then you can either wait util the next day when the quota is reset or you can use your own private key which can be obtained from Google at Google Cloud Platform. Google will require you to open an account and provide your credit card details but unless your usage of VLM is totally insane (more than 40,000 hits per month!) then there should be no charge.

2) Added drone options for Mavic 2 Pro and Mavic 2 Zoom

3) Removed Sound option – it never worked very well!

4) Added option to choose Heading Mode - this can be found in the Litchi tab of VLM Setup. For more information on this topic, please read the few posts immediately prior to this one.

I hope I have not introduced any new bugs - but it can happen! Please let me know if you find issues.

N

 

[joeruby]

Oh Oh.
I am seeing "to next waypoint" rotating in the opposite direction as before, and starting right away as the mission starts.

Try to simulate the mission below. It should fly the first leg (wp1 to wp2) at 0 deg (North), then transition and fly the second leg (wp2 to wp3) at 270 deg (West) etc, following with the camera tangent to the (blue curved) flight path.

Mission Hub - Litchi

Litchi's Mission Hub lets you plan waypoint flights and later execute them using the mobile Litchi app.

flylitchi.com

It's late, and I am tired. I should have probably waited until I am fresh to test this again in the morning. I hope I don't have "egg on my face" ha ha.

Maybe I didn't install it correctly. I will test again in the morning.
Joe
KC7GHT

 

[namirda]

Oh Oh.
I am seeing "to next waypoint" rotating in the opposite direction as before, and starting right away as the mission starts.

Try to simulate the mission below. It should fly the first leg (wp1 to wp2) at 0 deg (North), then transition and fly the second leg (wp2 to wp3) at 270 deg (West) etc, following with the camera tangent to the (blue curved) flight path.

Mission Hub - Litchi

Litchi's Mission Hub lets you plan waypoint flights and later execute them using the mobile Litchi app.

flylitchi.com

It's late, and I am tired. I should have probably waited until I am fresh to test this again in the morning. I hope I don't have "egg on my face" ha ha.

Maybe I didn't install it correctly. I will test again in the morning.
Joe
KC7GHT

Hi Joe,

I think what you are seeing is something called 'spline drift' When you specify TNW in VLM, the heading for each WP is simply specified as being towards the following WP. Sounds simple doesn't it! However, Google Earth wants to generate a nice smooth overall flight and tries to avoid long straight stretches followed by sharp turns like those you have in your mission. It does this by fitting a spline function to the headings and in the case of your mission, this causes a gentle drift to the right during the first leg so as to make the eventual left turn at WP2 smoother.

The best way to reduce this effect is to add more WPs on each of the straight legs - and there is a parameter for that! Go to VLM Setup/Smoothing and reduce the "Infill Distance between Smoothed WPs" to 100m. This will generate a few extra WPs on all your straight legs which will serve to constrain the spline and reduce the low frequency wobble in the heading.

The drift will also be much less if you simply increase your curve size at each WP.

Hope that helps.

N

 

[Chas2379]

Oh Oh.
I am seeing "to next waypoint" rotating in the opposite direction as before, and starting right away as the mission starts.

Try to simulate the mission below. It should fly the first leg (wp1 to wp2) at 0 deg (North), then transition and fly the second leg (wp2 to wp3) at 270 deg (West) etc, following with the camera tangent to the (blue curved) flight path.

Mission Hub - Litchi

Litchi's Mission Hub lets you plan waypoint flights and later execute them using the mobile Litchi app.

flylitchi.com

It's late, and I am tired. I should have probably waited until I am fresh to test this again in the morning. I hope I don't have "egg on my face" ha ha.

Maybe I didn't install it correctly. I will test again in the morning.
Joe
KC7GHT

Joe, did you change the Setup in Virtual Litchi Mission. You have to change Heading Mode in VLM Setup. You have three choices in the drop down menu.

 

[joeruby]

Hi Joe,

I think what you are seeing is something called 'spline drift' When you specify TNW in VLM, the heading for each WP is simply specified as being towards the following WP. Sounds simple doesn't it! However, Google Earth wants to generate a nice smooth overall flight and tries to avoid long straight stretches followed by sharp turns like those you have in your mission. It does this by fitting a spline function to the headings and in the case of your mission, this causes a gentle drift to the right during the first leg so as to make the eventual left turn at WP2 smoother.

The best way to reduce this effect is to add more WPs on each of the straight legs - and there is a parameter for that! Go to VLM Setup/Smoothing and reduce the "Infill Distance between Smoothed WPs" to 100m. This will generate a few extra WPs on all your straight legs which will serve to constrain the spline and reduce the low frequency wobble in the heading.

The drift will also be much less if you simply increase your curve size at each WP.

Hope that helps.

N

Namirda, that was it!! Splines. It is working great now using your suggestions above. I normally use more waypoints, but I noticed a difference in my actual video and my simulations in some of my flights, and thus created the long straight mission to demostrate the problem I saw. This allowed us to communicate, and you to solve the problem.

By the way I have asked Litchi to add to their wish list, to output the heading mode in the CSV data from Mission Hub for possible future use.

Thanks so much for your help.
Joe
KC7GHT

 

[joeruby]

Joe, did you change the Setup in Virtual Litchi Mission. You have to change Heading Mode in VLM Setup. You have three choices in the drop down menu.

Hi Charlie,
TNW (Toward Next Waypoint) simulation is working good now. Now I will have more confidence when I simulate a flight along a rock wall cliff. Once I know that I won't hit the cliff, then I can fly the same mission with the camera free, thus flying sideways along the cliff not looking where I am going.

Cheers,
Joe
KC7GHT

 

[marklyn]

Clarification please on the update... if I set up a VLM mission with custom headings (under settings) and use even small curves, GE is still showing the AC turning before it hits the start of the curve. If I change the settings in VLM to Toward Next Waypoint it seems to do better. What am I possibly doing wrong when I'm choosing custom headings that it's turning before it starts the curve?

 

[AMann]

Hi Namirda and fellow users,

Are there any steps one should take for installation over the old version?

Thanks!

 

[namirda]

Hi Namirda and fellow users,

Are there any steps one should take for installation over the old version?

Thanks!

Hi,

No special steps required.

Version 2.4 has a different ProductID from version 2.3 and so you can have the two installed together if you wish.

You can then remove 2.3 when you are happy that 2.4 is working properly.

N

 

[namirda]

Clarification please on the update... if I set up a VLM mission with custom headings (under settings) and use even small curves, GE is still showing the AC turning before it hits the start of the curve. If I change the settings in VLM to Toward Next Waypoint it seems to do better. What am I possibly doing wrong when I'm choosing custom headings that it's turning before it starts the curve?

Hi,

What you are seeing is how it is meant to be.

If you choose "To Next Waypoint", then the mission will be flown with the camera always facing forward. Any POIs will be ignored and the camera will only start to turn when you hit the curved parts of the mission.

If you choose "Waypoint Defined" then the camera will turn smoothly from one waypoint to the next. This is the way it was working in V2.3 and is presumably the most commonly used mode. POIs will be honored. The camera will turn throughout each leg of the mission and not only during the curved parts.

If you choose "Initial Direction" then the camera will not turn at all but will always point in the direction of the first leg. POIs will be ignored.

The default is "Waypoint Defined" which is the way it was working previously.

Hope that's clearer.

N

 

[AMann]

Hey all,

So when I downloaded the new zip file, my computer sees it as a zip.html file. What am I missing?

 

[namirda]

Hey all,

So when I downloaded the new zip file, my computer sees it as a zip.html file. What am I missing?

Not sure. The size of the file should be 65,992,230 bytes with an MD5 hash of C00102F27B62DE200135456A58EB1F2F

If that is the case with the file you downloaded then I would simply rename it to a .zip file and then extract the installer.
If that is not the case then you should be suspicious and download it again.

N

 

[AMann]

renaming it worked, thanks again!

 

[joeruby]

Hi Namirda,

I created and API Key OK and then pasted it into the settings VLM Google window. I pasted just the complete key itself. Then when I export a CSV from a VLM mission I get this:

5:57:05 PM Google Elevation API returned error
5:57:05 PM REQUEST_DENIED - This API project is not authorized to use this API.
5:57:05 PM Error Getting WP Ground Elevations from Google Earth
5:57:05 PM Error Correcting Waypoint Altitudes for reference
Can you give an hint? This is not urgent as I can easily go back to your key.
Joe
KC7GHT

 

[AMann]

Hi Namirda,

I created and API Key OK and then pasted it into the settings VLM Google window. I pasted just the complete key itself. Then when I export a CSV from a VLM mission I get this:

5:57:05 PM Google Elevation API returned error
5:57:05 PM REQUEST_DENIED - This API project is not authorized to use this API.
5:57:05 PM Error Getting WP Ground Elevations from Google Earth
5:57:05 PM Error Correcting Waypoint Altitudes for reference
Can you give an hint? This is not urgent as I can easily go back to your key.
Joe
KC7GHT

I get the same issue too. Joe, maybe it takes time to process?

 

[namirda]

Hi Namirda,

I created and API Key OK and then pasted it into the settings VLM Google window. I pasted just the complete key itself. Then when I export a CSV from a VLM mission I get this:

5:57:05 PM Google Elevation API returned error
5:57:05 PM REQUEST_DENIED - This API project is not authorized to use this API.
5:57:05 PM Error Getting WP Ground Elevations from Google Earth
5:57:05 PM Error Correcting Waypoint Altitudes for reference
Can you give an hint? This is not urgent as I can easily go back to your key.
Joe
KC7GHT

Not sure but I think the problem is that you need to authorize your API key to use the Elevation API and the Javascript API

N

 

[OzoneVibe]

Virtual Litchi Mission V2.4.0 is now available on Dropbox. As usual, the download link is available on the first post of this long thread.

Hmmm - a bit slow to the show …. I never got a notification on this brilliant thread. (Not your fault.)

Anyway - thanks for the update - brilliant news!