Mark Williams's Posts (11)

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Liverpool John Moores University are holding their second conference on the use of drones in environmental research on July the 7th and 8th. There are some great pieces of research being presented and it should be a very interesting couple of days.

I'm presenting my own research on the first day which hopefully should be of interest to some people. It will be great just to talk to other people involved in UAV research. If anyone else fancies attending you can buy tickets (£50 per day) from the  Liverpool John Moores events website

Below is a timetable for the two days. It would be great to chat to some DIYDrones heads at the event :)  

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I posted the results of my research into using a small UAV for land cover classification for habitat monitoring a couple of months ago.

I've created a short video as part of my research presentation that details the workflow used to analyse the image data and thought it may be of interest to the community. I'm more than happy to have a conversation about the project in the comments :)

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I've recently finished a research project using UAVs to classify land cover types on British upland heath. I'm using an APM controlled hexacopter (H550) carrying a Canon Powershot S95 modified for NIR photography. I've successfully surveyed and classified around 15 hectares in 10 minutes. Using image analysis software I've been able to classify the major land cover types with about 90% accuracy which is comparable to that obtained from imagery captured from much larger platforms using many more spectral bands.

An NDVI colour index of the orthomosaic was created and used in the classification process. This really helps in the spectral differentiation process. I think the results here show massive potential for the frequent, low-cost monitoring of the status of, and temporal changes in (sorry for the academic speak) many habitats, not just heathland.

The images below show the various outputs.

1. The full NIR orthomosaic

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2. The NDVI colour index

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3. The colour index overlaid on the green channel of the orthomosaic highlighting healthy and dead vegetation

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4. The classified land cover types in the GIS software (Purple is Calluna dominated heath, light green is rank grass cover, brown is cut heath and green are trees)

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I used ImageJ to create the NDVI colour index image, unfortunately it doesn't keep the GeoTIFF data in the output so I've used GDAL to georeference the colour index TIFF

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NDVI flight results

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Following on from my last post on modifying the PowerShot S95 for NIR photography. I have ran a couple of test flights to collect some heathland data. The last flight produced 134 photos which were stitched with Agisoft Photoscan and then processed with the Fiji Photo monitoring plugin to produce the NDVI image shown. Original output files can be found here

Areas of green/higher chlorophyll containing vegetation can be seen on the processed photo as green and red areas.

The photos from the camera are a little blurred right now as the 2007 filter is thinner than the IR block that was removed from the camera causing some focusing issues. I have a replacement non blocking filter on order that should solve this problem.

I'm making progress, I now need how to analyse this to get some quantitative data...

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Uwdh0h6.jpgAs part of an ongoing project to monitor natural habitats with a UAV I've modified a Powershot S95 to allow near infrared photography to capture some NDVI data. I've created a short how to video for anyone embarking on a similar task.The filters are supplied by publiclab.org as part of their infragram kit. The first test photos I have produced with FIJI and the NDVI plugin look promising.
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Arducopter problems in flight modes using GPS

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I'm having some strange problems with my hexacopter. The aircraft flies well in stabilise and alt hold but as soon as I switch to loiter or auto it flies off in a random direction whilst increasing pitch. It will eventually be almost vertical before I recover in stabilise mode.

Everything is well padded with foam and I have good GPS lock according to the logs. Does anyone have any ideas as to what could be happening here? Any help is much appreciated.

 I've uploaded logs here

https://www.dropbox.com/sh/7brm5m140lsuxnl/AAAy0X9o73_MUZ6M3z5oxJDSa?dl=0

And a couple of videos here




I ran compassmot getting a value of 62% and tried the flight again. Still having issues. The APM seems to be ignoring the external magnetometer and is using it's own instead despite changing the setting in mission planner.


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I finally getting the APM installed in my Bixler 2 this week. After a bit of tuning and configuration I ran my first aerial photography mission.

The image below shows the composite image overlaid in satellite imagery in Google Earth.

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This image shows the difference in quality between Google Earth's satelite imagery and my render

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Here's a 3D render of the area surveyed

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And here's me on the ground

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Overall I'm very happy with the first flight. There are some improvements to be made, I think most importantly, increasing the shutter speed to clear the photos up a little, maybe trying a lower flight to increase cm/pixels, flying perpendicular to the wind and finding a new flying  site.

My equipment set up is as follows:

HobbyKing Bixler 2

Turnigy 9x

APM 2.5 with GPS and telemetry

DroidPlanner to tell me what's going on in the air :)

Canon IXUS 220 HS running CHDK and a modified FPV_UAV script to allow control from the ground

Agisoft Photoscan for rendering

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First flight with APM complete

I finally got around to testing out Ardupilot on a real flight. It was far too windy for a test flight and so was short and untidy. I'm now waiting for a calm day to get it tuned. I have an APM 2.5 installed in a HobbyKing Bixler 2.

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There was some bad "porpoising" when I switched to auto. The pitch P value needs to be reduced though this is going to be time consuming with just myself at the field. The weather on Friday looks calmer so maybe I'll have another update soon.

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Getting there

I made three test flights today with my Bixler 2 UAV. I have an IXUS 220 HS installed in the fuselage which is operated remotely using the gear switch on the transmitter.

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 A 3D model of the field I was testing over can be seen below. The model is far from perfect as I was piloting the aircraft manually. I am waiting on an APM board at the moment and this should definitely improve things.

I've uploaded a short video about the set up to YouTube

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