How to shoot satellite-style imagery of an area

[Milo]

Hello —

I have a MavicPro, Litchi and Lightroom.

I’m hoping to set up a waypoint mission where I task the drone with taking a grid of pictures directly below it, and then stitching them together to create a faux-satellite image of our bay. (To map out changing sand banks, etc.) Does anyone have any experience of attempting anything like this? Any tips?

Best,
-Miles.

 

[DB Cooper]

Microsoft had a great online program for this called photosynth. I think it has been shut down though. Might try searching google for references to it. There has to be another replacement of it somewhere.

And I believe google maps is doing some sort of the same thing with a timeline feature as well....

Worth a look anyway.

 

[AlanTheBeast]

If there are a lot of high objects (sand dunes on the beaches; towers), then you'll have parallax issues. For the flat surface, not so much. Lens distortion is another unknown though the Mavic camera seems relatively flat to me.

I'll just barf these out as I think of them:

One real problem will be knowing the exact heading of the drone and whether the drone gimbal is (or is not) correcting for drift when you snap each photo so that when you stitch you know they are square to each other.

(When the camera is pointing straight down it may (or may not) be rotated to correct for drift. Already we know that in a well calibrated and set up system it's not unusual to have tilted horizons ... how that all translates to the "roll" correction of the camera (into yaw when pointed down) is something I wouldn't hazard a guess on .... maybe someone else ...)

You could find some nice square/rectangular farmers fields to practise this over while observing the effect of a crosswind on the orientation of each photo v the real world (Google Earth).

Finally when stitching, if you don't have landmarks of known positions I don't know at all how you will accurately stitch these together. Each photo should be tagged with the position of the photo, but then it's pretty hard to compute the edges (never mind the overlaps) unless you know very accurately how high you are above the surface. You may need some "farmer's field" data to compute those.

I don't need to mention that automatic stitching s/w might not work at all given wind, wave and current conditions, etc. unless there are some very visible and contrasting 'hard" features for it latch onto.

Good luck and I hope to read about your adventures and results.

 

[BD0G]

You have lichti already so you could setup a waypoint mission that is a rectangle or square that has the camera focused downward at a POI for each of the waypoints. Then the Mavic would fly to each of the Waypoints and then hover briefly while shooting a pic of each of the POI's . Then continue to each of the other Waypoints and continue the process

There would be considerable trial and error as you would want a certain amount of overlap on each of the pictures so that you could stitch them together in something like Microsoft's ICE (Image Composite Editor).The nice thing s that once you capture the proper grid and mission it is easily repeatable by launching the mission from Lichti and flying it again and again.

Personally I would visit SkyCatch and run a trial version of thier software as you are trying to reinvent the wheel. Sadly they are still working on thier Anroid Version and only have one for iOS devices presently
Skycatch: Drone Image Processing Platform

Its $49.00 for the full version and it is targeted at terrain mapping.

****! Mavic Pro support has still not been released ! They touted this months ago, but still have not released it.

 

[BD0G]

Propelloraero is another possibilty as they have partnered with DJI

 

[AlanTheBeast]

You have lichti already so you could setup a waypoint mission that is a rectangle or square that has the camera focused downward at a POI for each of the waypoints. Then the Mavic would fly to each of the Waypoints and then hover briefly while shooting a pic of each of the POI's . Then continue to each of the other Waypoints and continue the process

There would be considerable trial and error as you would want a certain amount of overlap on each of the pictures so that you could stitch them together in something like Microsoft's ICE (Image Composite Editor).The nice thing s that once you capture the proper grid and mission it is easily repeatable by launching the mission from Lichti and flying it again and again.

Personally I would visit SkyCatch and run a trial version of thier software as you are trying to reinvent the wheel. Sadly they are still working on thier Anroid Version and only have one for iOS devices presently
Skycatch: Drone Image Processing Platform

Its $49.00 for the full version and it is targeted at terrain mapping.

****! Mavic Pro support has still not been released ! They touted this months ago, but still have not released it.

I think the real issue here is that he'll be over water. Not much to stitch from due to waves, wind, current ...

 

[Milo]

It's a very shallow bay, so it is over water but there are lots of distinguishing marks. (Oyster pens, sand banks, etc etc) Great advice folks!

 

[Milo]

Scott's Point, Samish Island

 

[AlanTheBeast]

It's a very shallow bay, so it is over water but there are lots of distinguishing marks. (Oyster pens, sand banks, etc etc) Great advice folks!

Great - that will help. Good luck and I look forward to seeing how you did.

 

[pyjamasam]

I have used one of the many apps available to do the mission flight/image capture and then I was playing around with opendronemap to do the processing and produce a geo-referenced image that can be overlaid onto existing maps.

It worked well but I had flown a little low (30m) and ended up with about 380 images (mapping about 7 acres) and it took a LOT of ram to process and in the end I did batches of like 200 images and the combined the results into a single image.

It didn't turn out as nice as if all the images were processed in one go, but until I can throw some more ram in my VMware server it's what I have to work with.

Weather hasn't been super great lately (lots of wind and cold) and my mavic is off getting a new camera, but once I get it back and spring finally shows up I am going to retry at 40 or 50m to reduce the image count.

Chris.

 

[AlanTheBeast]

I have used one of the many apps available to do the mission flight/image capture and then I was playing around with opendronemap to do the processing and produce a geo-referenced image that can be overlaid onto existing maps.

It worked well but I had flown a little low (30m) and ended up with about 380 images (mapping about 7 acres) and it took a LOT of ram to process and in the end I did batches of like 200 images and the combined the results into a single image.

It didn't turn out as nice as if all the images were processed in one go, but until I can throw some more ram in my VMware server it's what I have to work with.

Weather hasn't been super great lately (lots of wind and cold) and my mavic is off getting a new camera, but once I get it back and spring finally shows up I am going to retry at 40 or 50m to reduce the image count.

Chris.

Cool. I suspect our Mavic's will be sharing a ward room at the Carson Hospital for Sick Mavics. Just shipped Thur, just cleared US Customs in Plattsburgh. Hopefully at Carson on Mon/Tues... my camera is soft on the left side. What's with yours?

Given the amount of detail even at 100 m altitude I'd believe that sufficient for locating sand bars?

 

[SteelFlyer]

Try MapsMadeEasy or DroneDeploy. Both are specifically designed for this purpose and both offer free versions with limited capabilities.

 

[Milo]

Chris- would love to see what you came up with. Can you share?

 

[pyjamasam]

Hopefully these images show up correctly. Please let me know if they don't

These are really low res versions of what I ended up with. The process actually re-sizes the images down to deal with them in a mildly sane timeframe, but I still ended up with a 12MB TIFF at the end. And there was some good zoomability still left in the image. If you want to process full res images you'll need even more RAM!
The VM I was using to host the docker image for OpenDroneMap had 10GB of RAM dedicated to it, and I still had to process in batches, and you can clearly see where I had to process in batches. And due to that there are some inconsistencies in the generated ortho image. But this was my first attempt at this entire process.

I can't remember which app I used on the phone to fly the mission, but I have a variety loaded:
- DroneDeploy
- Altizure
- Airnest
- Pix4DCapture
- InFlight
- Skycatch
They all let you set up an area to survey and then generate and fly the waypoints needed to get the coverage your looking for.

Most of them require registration to use, but I never signed up for a paid account. I am just leveraging the mission planning of their phone apps. I then did the image processing my self using OpenDroneMap (GitHub - OpenDroneMap/OpenDroneMap: OpenDroneMap is a tool to postprocess drone, balloon, kite, and street view data to geographic data including orthophotos, point clouds, & textured mesh. In the tradition of the Ship of Theseus, it was originally forked from qwesda/BundlerTools https://github.com/qwesda/BundlerTools.).

The Ortho image that is generated is actually a flat image generated from a full 3d model. You can kinda see a bit of the 3d object (like the red barn with the solar panels). Because of this and how low I was flying some of the parallax in the images caused some strange artifacts in how the objects were generated from the point cloud.

OpenDroneMap also generates point clouds and more. I am going to try and model my barn when I have a flying aircraft and warm temps again.

And as always, you get what you pay for. For my uses a free solution that I could mess around with was perfect. I realize the quality isn't up to what the big boys like DroneDeploy or Pix4D produce, but it's good enough for me

Hope that helps.

Let me know if you need any more information.

Oh ya. My Mavic is in getting a new Gimbal/Camera due to Jello'ie/Wavy video :-( . Its been delivered, but the ticket hasn't registered its there yet.

chris.

 

[HeavensAbove]

I find attaching a solid fuel stage to my Mavic and launching to a low earth orbit of 1200 miles allows me to take excellent satellite style shots. Unfortunately, there have been problems with down link video feed and I'm currently looking at assistance in retrieving it.

As has already been said your issue is flying at maximum of 400 feet and geometry of anything which protrudes from a flat landscape - features, buildings, hills. It is always going to not look quite right when stitched. The only way forward would be it an app which could stitch from video and only use a very small part of the image when stitching. Only problem is each pass would need to be REALLY close to the previous, and it would take multiple passes, and therefore multiple flights to produce one decent image.

Is it worth the effort? I'm going to just use Google and hope they update my neighbourhood which hasn't been photographed since at least 2003.

 

[Milo]

The sand banks in the bay shift every time there's a storm, so Google Maps doesn't quite work for me ;-)

 

[Milo]

Phenomenal info! (But I can't access those images due to a permissions issue)

 

[AyeYo]

You can do this with no hassle, for free with Drone Deploy and (and even easier) Altizure. The image quality of both will far exceed Google maps satellite view. Alitzure is about the easiest mapping program I've used because it pre-makes the grid. Just set flight altitude and amount of overlap and it adjusts the grid for you.

 

[Qoncussion]

It's a very shallow bay, so it is over water but there are lots of distinguishing marks. (Oyster pens, sand banks, etc etc) Great advice folks!

Over water with distinguishing characteristics, use a polarizing filter to cut through the water, allowing more of the under water landmarks to be visible for stitching.

 

[pyjamasam]

... I can't access those images...

Should be good now. I moved them and re-linked. Let me know if you still have issues or any other questions.

chris.