Octacopter UAV survey at Blelham Tarn bloomery, Windermere

Aerial plan view of Blelham Tarn bloomery

Aerial plan view of Blelham Tarn bloomery

Jamie returned to Blelham Tarn last weekend to undertake aerial survey on the site of the bloomery as no excavation was taking place. He used his octocopter, one of two  UAV we have at the company, to take multiple vertical images across the site. The north-western half of the site was covered in trees but the main area of the bloomery mound/platform where the four trenches were opened up was surveyed in full. From the photographs taken we were able to process them in Agisoft to create three outputs which will be really useful in trying to get an understanding of the subtle topography and earthworks for this site. First we have a flattened aerial plan view of the visible parts of the site which can be overlain on the survey data I took last week.

An oblique view of the 3D model of Blelham Tarn bloomery

An oblique view of the 3D model of Blelham Tarn bloomery

Then we have the 3D contour model of the detailed topography of the site which we can spin around, zoom in and out of, and pick up fine detail from. The screenshot above shows the model with the photo layer draped on, the one below shows it as the solid 3D generated model. Again from these we can pick up subtle details of the site and surrounding topography, and also see the trenches, spoil heaps and turf stacks!

An oblique view of the solid 3D model of Blelham Tarn bloomery

An oblique view of the solid 3D model of Blelham Tarn bloomery

Finally we can create close contours from the 3D model (these here are at 10cm intervals) which are overlain on the rough survey data we took last week – open the image below and zoom it to have a look. We found that the contours were very detailed for this particular site and were (obviously) better than ones generated from LiDAR data for the region, which at 1m accuracy really didn’t show much of the earthworks themselves, and were also offset slightly from the survey data. We have found that the Agisoft contours are better at depicting earthworks of discrete complex sites, whereas the LiDAR contours at 1m resolution are fine for broader areas and showing the surrounding natural topography.

Rough survey data of Blelham Tarn bloomery overlain with 10cm contours created in Agisoft

Rough survey data of Blelham Tarn bloomery overlain with 10cm contours created in Agisoft

I will use all of this information tomorrow when we go back out to site with the volunteers to finish off and do annotated hatchure drawings of the bloomery.

 

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5 thoughts on “Octacopter UAV survey at Blelham Tarn bloomery, Windermere

    • I’m still learning how to use ours so that I can put in for my commercial flying license for it. I can’t wait to be using it in anger myself as it can do so much for recording earthworks, excavations and standing buildings.
      I will be posting more about some of the projects we have been undertaking with them recently.

      Reply

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