Camera Field of View

[Fleamavic]

Hi
A newbie here. thanks to everyone that posts and responds. DJI is terrible at it!
Sorry if this is on another thread, but what I think is a pretty thorough search hasn't revealed it

A couple of questions about mapping and grid setup.

1) Camera Field of View. Without using an app like Drone Deploy/litchi etc, I have been trying to set up a grid pattern to fly. I can't figure out what field of view is for the Mavic camera. The specs say it is 78.8 degrees, but when I do a test with meter long sticks from different heights, I get a very different number. ..my photos show a difference between horizontal (52.7 deg) and vertical (39.6 deg). This matters for photo overlap of course since the coverage will change with altitude above ground. Anyone know why this might be? Is there (I doubt it) a setting somewhere I am missing?

2) I am also having trouble making my Mavic Pro connect to Drone Deploy. Is it possible to set up a grid on google earth and somehow import that into the DJI go app?

3) Is there a way to tell the Mavic to fly in a given direction / compass bearing?

Too many questions in one post?

Thanks! Any pointers in the right direction would be appreciated.
J

 

[Keule]

Hi @Fleamavic,

first of all, welcome to Mavicpilots!

to your questions:

1) I don't know exactly how you are doing this, but i advise to use any of the (free) apps to actualy create, fly and capture your images. Look for MapsMadeEasy, Pix4D, Dronedeploy to name a few.
These apps setup your camera parameters correct.

2) DroneDeploy works fine with MavicPRO - Never had an issue.
You can set up a grid in GE, but there is no way to import that .KML into GO4. You should use
DJI GroundstationPro to di this and fly your mission.

3) again, use Groundstattion Pro, and you can fly your mission at a specified heading.

I hope that helps,

//K.

 

[Keule]

It looked to me, that you were performing your calculations in question 1) using the physical characteristics of the lens (~4mm focal length) instead of the 35mm equivalent...

 

[bushie]

DroneHarmony is free and it will allow you to define an area you want to map, and set parameters such as overlap
I have used it a number of times and it works well

 

[Fleamavic]

Hi @Fleamavic,

first of all, welcome to Mavicpilots!

to your questions:

1) I don't know exactly how you are doing this, but i advise to use any of the (free) apps to actualy create, fly and capture your images. Look for MapsMadeEasy, Pix4D, Dronedeploy to name a few.
These apps setup your camera parameters correct.

.....

//K.

 

[Fleamavic]

Thanks
From my browsing, it seemed that only Drone Deploy had a free app for this. - and not sure if it continued after trial period. I will check out the others to see if I can find how to get that part for free. I have been tinkering with opendronemap for processing. Unfortunately it has no grid set-up that I can find.
J

 

[Fleamavic]

DroneHarmony is free and it will allow you to define an area you want to map, and set parameters such as overlap
I have used it a number of times and it works well

Thank you, I'll give it a 'whirl'.

 

[Fleamavic]

It looked to me, that you were performing your calculations in question 1) using the physical characteristics of the lens (~4mm focal length) instead of the 35mm equivalent...

Hmm...not sure what you mean here. I tried it using the 78.8 degrees I found in the specs, then tried it at several altitudes in the field using a 13 metres line of sticks marked at 1M intervals. As noted above, I got very different results. Not sure how to interpret that now.
I thought the Mavic had a 26 mm lens. {FOV 78.8° 26 mm (35 mm format equivalent) f/2.2 ). I am not camera smart enough to know how a 26mm can be equivalent to a 35. - or in fact what that would mean in this case.

I see I need to dig a bit more....the hole is getting pretty deep at this point!

Thanks
J

 

[Keule]

From my browsing, it seemed that only Drone Deploy had a free app for this.

Not only DD has a free app, also Precision Mapper, Pix4Dcapture and DJI's own app, Ground Station PRO are free.

 

[Keule]

I see I need to dig a bit more....the hole is getting pretty deep at this point!

I don't want to stop you from further investigations ;-) but go the easy way: Just setup your camera/drone in one of the apps i mentioned and you are good to go.

 

[Fleamavic]

Not only DD has a free app, also Precision Mapper, Pix4Dcapture and DJI's own app, Ground Station PRO are free.

Cool, I'll check them out
Thanks
J

 

[Fleamavic]

I don't want to stop you from further investigations ;-) but go the easy way: Just setup your camera/drone in one of the apps i mentioned and you are good to go.

Not to worry...you won't stop me. I like to get down and dirty....it helps me learn more rather than just be the computer the drone is. Not that I won't use the apps...but I like to know how/why things work regardless.

Interestingly, so far no-one else seems to know the answer to my question of FOV angles. Wonderful to have so many helpful responses so quickly...thanks to all

J

 

[Lake_Flyer]

In GroundStation Pro it is very easy to choose the right camera. But then again, it's DJI's own app.
However, it's Apple IOS only. GSPro and Autopilot where the main reason why I got me an iPad2 some years ago.

 

[Lake_Flyer]

how a 26mm can be equivalent to a 35

That has to do with the smaller sensor.

 

[Keule]

so far no-one else seems to know the answer to my question of FOV angles

The number in question (78.8°) is the FOV measured diagonally on the sensor.

 

[Fleamavic]

DroneHarmony is free and it will allow you to define an area you want to map, and set parameters such as overlap
I have used it a number of times and it works well

Thank you all for your responses. I thought I had responded individually, but don't see them here...Did you get them? what am I doing wrong if not....?..

 

[Fleamavic]

The number in question (78.8°) is the FOV measured diagonally on the sensor.

Thank you so much for that. Knowing that I recalculated and discovered that the recorded image height is out by about 5 metres. I took the photo at 40 m (according to the realtime flight indicator) but the metadata file says it was at 34.9 m. ....but 30 m gives the right FOV number, but why would the Meta data be recorded as something different...? how can a computer be confused? I guess more testing is in order for that one to get resolved.

J

 

[crofter]

Very interesting conversation for me, another newbie. I need to fly a grid pattern at monthly intervals to monitor the growth of saplings. Which app did you use eventually? I have the Mavic Air and use IOS.