Get more from your Mavic
The largest Mavic community in the world
Join Us Now

Mavic 2 Enterprise Advanced Thermal Map in Pix4D

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
I finally had time to go out and obtain the images to make a thermal map with the Enterprise Advanced.

Pix4D wanted 90 front and 90 side overlap per the directions and I found this to make the aircraft fly at only 2-3 mph. I do think that DJI Pilot does not have the correct information about the camera settings for mapping as it could of flew much lower and faster as there was such a long period between images.

When processing in Pix4D the software recommended using the settings for a FLIR Tau 2 sensor with 640 resolution.
When I tried using the Mavic Enterprise Advanced 620x512 setting the images would not stitch. I am going to try to make my own camera setting using the settings from the FLIR, but tweaking them a bit.

Overall I am very happy with the output though as when I compare it to regular images, it stitched this low sloped roof extremely well.
I chose this building as it is known to have leaks all over and I know where they are. It is basically a perfect place to train on qualitative thermography dealing with low slope roof moisture in the insulation.

Roof Specs:
Built-up Roof Covering (Not Modified Bitumen as far as I can tell due to the spacing between layers)
Unknown insulation under the covering
Corrugated metal decking for sheathing

Today's environmental factors made it an okay day for this.
Temperature got over 45* F
The sun was out and thermally loaded the roof
The wind was 10mph, but had gusting over 20mph at times.

1636686914312.png

Orthomap of thermal images.
Take note that until DJI releases and SDK that Pix4D can use, you can only make a thermal map without the radiometric data embedded in it. The above map is more like an RGB ortho.

Compare the above with this image of the building and you can see that the stitching was very good.
1636687079458.jpeg

For those who want to try on solar panels, keep in mind that due to the angle of the panels you must get the drone to line up the same way or you will run into problems. Raptor Maps explains this well in their article on how to use this new drone for solar mapping.

I did not have this problem as my target has only the slightest of an angle.
 
  • Like
Reactions: Faquaral

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
You got some very nice results there!
We have tried to process in Pix4D too but with no success, it just won't stitch
Would you be ok to share your tweaked camera profile settings?

Thanks!
 

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
First make sure you have very high overlap. I used 90 and 90, but will experiment with lower in the future.
Next do NOT choose the Mavic 640x512 camera option. Use the Flir Tau 2 option.
Do not choose to make a thermal map, but choose to make an RGB map.
It should work from here. When done processing, go back to the Images Properties Editor under Process and then go to Selected Camera model. Choose Edit, then Load Optimized Parameters. You can save for the future or not save. You can also save as your default, but I did not. Now go back and Reoptimize (Quicker) or run Step 1 all over again.
Your Camera Optimization on your Quality Report should now be under 5%.

Keep in mind, this is NOT a radiometric thermal map, it is an RGB processed map with no temperature values in it.
Also keep in mind, due to this thermal camera not allowing you to lock in a range, the same temperature assigned to a color will vary. Since the temperature range is not locked for the flight and as the scenery and temperatures in regards to highest and lowest in FOV change, 85 degrees in one image may be bright white and in another it may be several shades darker.

Let me know if you need help, I can PM you.
 
  • Like
Reactions: Faquaral

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
Many thanks for your reply!
I'm getting somewhere with the stitching now in rbg map, though with the help of a few manual tie points. It's still not perfect probably not quite enough overlap but still I'm glad it works

Regarding the map not being actual thermal but rgb, plus with no lockable range the result is not super useful for any kind of analysis if I'm understanding correctly...
So what if we were able to convert the jpeg to flir rjpeg and process that, would it become usable for a true radiometric thermal map?
There is a guy who has a converted currently in beta, they talk about it on reddit https://www.reddit.com/r/UAVmapping/comments/ppq97c/_/hdhrs3x I have tested the tool and it seems to work to convert to rjepg and/or tiff, however no success yet on stitch the thing yet with Pix4D even with the custom camera parameters
 
Last edited:

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
I think your stitching issues are from a lack or sufficient overlap as you said.

The lack of locking range is a problem but in my example, it did not affect the final outcome. I compared my images to the orthomap, and it is spot on.

I know that with the Matrice 300 RTK's H20T (Which shares the same exact thermal sensor), there have been several people that have been able to convert their thermal outputs into an RTiff and then were able to use these in Pix4D to make a true radiometric orthomap. So I think in the future someone will figure this all out and we will be able to get a stitched radiometric thermal map.

Thank you for the above link, I will definitely look into this.
 
  • Like
Reactions: Faquaral

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
I was able to use Drone Deploy for the same dataset and the results were interesting. From the link given on the Reddit post listed above someone stated that Drone Deploy could process a true radiometric orthomap with temperature data.

And yes it did work.

Screen Shot

1637340418187.png

It did not stitch as nicely as Pix4D, but it is not bad.

Temperature comparison. Comparing the Drone Deploy radiometric orthomap temperatures to temperatures in the RJPEG images using the DJI Thermal Analysis Tool.

Pix4D - No temperatures given as it is an RGB stitch
Drone Deploy
Fire Pit (Bright Spot in the front left corner of building.
1637340668144.png
Drone Deploy has the highest temperature as 82.5* F

1637340876059.png
DJI Thermal Analysis Tool shows a Max of 350*F


Drone Deploy has some work to do on this, but I am happy that they have made progress.
I hope the rumored massive update for the Enterprise Advanced is true and soon. Maybe we get some of the features that we have been asking for.
 
  • Like
Reactions: Faquaral

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
Thanks a lot for your input and sharing your research, definitely interesting to know that it works out of the box with DroneDeploy, though not very accurately yet.

How high above ground were you flying for this particular dataset? DroneDeploy makes a mess of our images, so there really is a problem with our flight pattern and/or height
 

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
Thanks a lot for your input and sharing your research, definitely interesting to know that it works out of the box with DroneDeploy, though not very accurately yet.

How high above ground were you flying for this particular dataset? DroneDeploy makes a mess of our images, so there really is a problem with our flight pattern and/or height

I was at 138 feet AGL.
90 front and 90 side overlap
Nadir camera angle
White Hot palette

I chose the Thermal Camera Option and not RGB in DJI Pilot.

When you take a good look at the Drone Deploy output, it had some stitching issues. The Camera Optimization is very poor. I think it will get better as they tweak the settings.
 
  • Like
Reactions: Faquaral

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
Thanks I will report back when we have done the flight and tested on Pix4d 👍🏻
Weather is currently stormy around here so we have to wait… 🙁
 

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
So we finally managed to get a flight done and thanks to your input were able to get a good dataset that did stitch in Pix4D rgb mapping
Screenshot 2021-11-26 182617.png

Then after converting the files to rjpeg using the tool mentioned previously and the camera calibration data from the rgb processing, we successfully stitched a thermal map with Pix4D, outputting a nice thermal reflectance map

All temperatures are in degrees centigrade
Screenshot 2021-11-26 18.42.12.png
Reflectance map in Pix4D.

Screenshot 2021-11-26 200908.png
Zoom on an area of the Pix4D map with a different scale to focus on the hot spots

Screenshot 2021-11-26 200950.png
Same area on DJI Thermal Analysis Tool (just not the same orientation)

It seems the values are not too far off from the ones we get with DJI Thermal Analysis Tool, though as you may notice there is a very bizarre darker band in the Pix4D map, which roughly corresponds to the first part of the mission. That part of the building is not heated, so it's normal that it appears colder but the tarmac on the ground is the same all around the building.
Checking the temperatures in Thermal Analysis, it does fit with the Pix4D map, so this difference either exists or there is another source of error.
The first flight was performed before dawn and the second finished just after but it was an heavily overcast cold day (around 3°C) so not really that much radiation from the sun. Is it possible that there is a drift caused by the thermal sensor heating slightly during the flight as it's an uncooled sensor?
To give you an idea, the first flight was started on north of the building, second flight ended on the eastern side. For some unknown reason the drone flew slower or took more picts on the second flight even though the parameters were the same in dji pilot.
Screenshot 2021-11-26 222201.png

We also tried to stitch the data with DroneDeploy but it made a mess of it all, so yeah their camera optimization is not on point yet.
Screenshot 2021-11-26 220920.png
 
  • Like
Reactions: jaja6009

jaja6009

Well-Known Member
Joined
Jul 14, 2019
Messages
76
Reactions
55
So we finally managed to get a flight done and thanks to your input were able to get a good dataset that did stitch in Pix4D rgb mapping
View attachment 139096

Then after converting the files to rjpeg using the tool mentioned previously and the camera calibration data from the rgb processing, we successfully stitched a thermal map with Pix4D, outputting a nice thermal reflectance map

All temperatures are in degrees centigrade
View attachment 139098
Reflectance map in Pix4D.

View attachment 139099
Zoom on an area of the Pix4D map with a different scale to focus on the hot spots

View attachment 139100
Same area on DJI Thermal Analysis Tool (just not the same orientation)

It seems the values are not too far off from the ones we get with DJI Thermal Analysis Tool, though as you may notice there is a very bizarre darker band in the Pix4D map, which roughly corresponds to the first part of the mission. That part of the building is not heated, so it's normal that it appears colder but the tarmac on the ground is the same all around the building.
Checking the temperatures in Thermal Analysis, it does fit with the Pix4D map, so this difference either exists or there is another source of error.
The first flight was performed before dawn and the second finished just after but it was an heavily overcast cold day (around 3°C) so not really that much radiation from the sun. Is it possible that there is a drift caused by the thermal sensor heating slightly during the flight as it's an uncooled sensor?
To give you an idea, the first flight was started on north of the building, second flight ended on the eastern side. For some unknown reason the drone flew slower or took more picts on the second flight even though the parameters were the same in dji pilot.
View attachment 139102

We also tried to stitch the data with DroneDeploy but it made a mess of it all, so yeah their camera optimization is not on point yet.
View attachment 139101

Wow, great job on this!

The Pix4D RGB map came out excellent. What settings did you use?
Overlap Side and front?
Altitude?
Nadir?

I will have to try the RJPEG to RTIFF Tool to process my data to see how my Pix4D Reflectance map turns out.

I want to try and figure out is I am overdoing it with my 90/90 overlap.

I still think that if we could lock the temperature range/span, the outputs would come out better.

Drone Deploy needs to tweak their camera settings as well as the temperature values, but seeing how they have always been very good with adding new support I think it will come.

When I get some time I will try a Reflectance map in Pix4D with my original data.

I will also be adding a solar panel field. Raptor Maps has a good video showing how to use DJI Pilot to obtain the correct orientation for solar fields.
 

Faquaral

Member
Joined
Nov 18, 2021
Messages
6
Reactions
1
Location
Switzerland
Wow, great job on this!

The Pix4D RGB map came out excellent. What settings did you use?
Overlap Side and front?
Altitude?
Nadir?
For the flight we used settings as you suggested:
40m AGL (138ft)
90% overlap front and sides
100% Nadir images
DJI Pilot camera type: M2EA thermal
Photo mode timed interval shots
Don't remember the flight speed but very slow, total flight duration was around 40min
472 thermal images in total

For the RGB processing, I just used the standard pix4d mapping template
Screenshot 2021-11-29 094153.png
Camera calibration parameters obtained for the RGB map

Then for the Thermal map, I used the Thermal Camera preset:
Screenshot 2021-11-29 095816.png


And with the following custom camera calibration parameters:
Screenshot 2021-11-29 090256.png

I will have to try the RJPEG to RTIFF Tool to process my data to see how my Pix4D Reflectance map turns out.

I want to try and figure out is I am overdoing it with my 90/90 overlap.

I still think that if we could lock the temperature range/span, the outputs would come out better.
It would be interesting to know if stitching can be done with less than 90% overlap as it considerably increases flight time, during which external factors such as sun radiation will vary considerably I guess.

Let us know how it goes, especially regarding solar fields as we don't really have such things around here


I have been thinking about our reflectance map and this strange temperature variation around some part of the building. Notice that it's only around the heated part of the building, so I'm starting to think that we are seeing the radiated heat of the building being reflected on the tarmac.
I just watched this interesting webinar about emissivity and they talk about how reflectivity from other sources can be a very important factor

My current theory so far, but I might be wrong:
Screenshot 2021-11-26 18.42.12 - Copy-edit.png