Hello and thanks, in advance, for advice.

I just got our Matrice 210 for mapping - we needed to do both thermal and visible spectrum mapping to look at plant health in different ecosystems. We are researchers at Coumbia University looking at environmental impacts on ecosystems.  We have been using DJI Phantoms and Mavic Pros, but we needed a dual camera mount system.  The Matrice 210 has lots of limitations however, many of which are discussed in these forums.

My questions concern the GPS unit.  I am using the dual downward gimbals.

1.  I believe that if you do not install the upward gimbal, you do not need the external GPS.  Is that true?
2.  Is the external GPS better than the internal GPS?  The external GPS requires plugging into the UAV which means having to leave the plug cover open and there's extra weight, but if the external unit had better reception or was better in other ways, then I would use it.

Again, thanks for you advice.

good question. the only thing I know is that the M210 with external GPS is not anymore waterproof.

You're going to get very similar data either way...we're not talking about you comparing high end IMU's to consumer grade, or D-RTK to GPS.

I'd say you're fine to leave it off. I've flown both with and without it (even with a top camera mounted) and have never noticed a difference.  Based on my (limited) experience running dual gimbals I think your bigger concern is going to be figuring out how to successfully get both to map at the same time. The dual gimbal functionality has been less than ideal but I haven't tried dual mapping yet. Maybe it will work without any problems.

YOYOMAN Posted at 2018-1-26 05:35
good question. the only thing I know is that the M210 with external GPS is not anymore waterproof.

ThanksI  Yes, you are right.  I noticed this when trying it our.

HyperSpectral Posted at 2018-1-26 07:22
You're going to get very similar data either way...we're not talking about you comparing high end IMU's to consumer grade, or D-RTK to GPS.

Thanks!  This answers my question.

dronie326 Posted at 2018-1-26 15:26
I'd say you're fine to leave it off. I've flown both with and without it (even with a top camera mounted) and have never noticed a difference.  Based on my (limited) experience running dual gimbals I think your bigger concern is going to be figuring out how to successfully get both to map at the same time. The dual gimbal functionality has been less than ideal but I haven't tried dual mapping yet. Maybe it will work without any problems.

Thanks so much!  I'll leave it off.  I agree with your observation that the bigger challenge is the dual mapping.  It's been a challenge to stitch together thermal images as it is - they tend to be soft and any change in conditions (a cloud passing over, wind, etc.), and the images will be different.  Photogrammetry really works on the idea that the thing you are imaging is static.

On the other hand, without the visible, it's tough to know what you're looking at, so even if the stitching fails, we're better off than when we flew separately.

Of more concern is the fact that the M210 comes with the CrystalSky monitor, which is Android, and DJI has yet to make the promised version of their GS operational.  I can switch to an iPad, but that's more costs and a monitor that is not as good, and the software, even if it was Android, has the lowest customer rating of the majority of mapping software.  But 3d party software for running dual cameras seems unavailable.

Still, as researchers, never has any piece of new technology come without myriad headaches.  We want to know if the tundra permafrost is melting, are diseases taking out our forests, is sustainable farming really sustainable - we've got a lot of motivation to find answers and the M210 seems promising.

Thanks again!

Thanks, again.

Nice setup and project.
I'm also a biologist, working with P3, P4, M210 and M600 for al sorts of biological monitoring, sampling and development.
Presently the focus is on seagrasses, blue mussels, terrestrial protected nature and a lot more.
Right now integration of our MicaSense rededge and flir vur pro r is my most current task.

Possibly be better to fly separate missions.
Been told by Pix that for decent thermal stitching you need 99& overlap as the resolution is so low on most thermals that go on drones.

broadlandboy Posted at 2018-4-16 02:29
Possibly be better to fly separate missions.
Been told by Pix that for decent thermal stitching you need 99& overlap as the resolution is so low on most thermals that go on drones.

What is the XT lens the most suitable for thermal mapping by drone? 13-19-25mm ?

Personally would have thought 25mm as the resolution would be best but this is just my opinion with no expertise to back it up.

Hi all --

I'm running M210 with Zenmuse XT and RedEdge (though flying separate missions with single gimbal). The RedEdge works well via Atlas Flight. The XT, though, has weird GPS issues. If I fly a grid, either in P4Dcapture or just with iOS DJI XT PRO (a "manual grid") and capture, say 30 images, there will probably be only about 10 unique GPS locations recorded in the image EXIF information. The flight seems fine (though I have not downloaded the flight log, which could be illuminating). Figuring, that the photos were actually fine, just with bogus EXIF info, I tried to stitch them in P4D to no avail.

Anyone else run into a similar issue? The reason I'm posting here is because my last best thought on a temporary solution is to mount the auxiliary GPS even though I will not use the upward mounted gimbal.

The attached image is the image locations in P4D based on the EXIF data. The single grid actually flown looked normal in P4D capture and IRL.

Thanks,
Mike