Vikings, high winds and the North Sea. How Trimble X7 and Scansite encountered unusual challenges at Lindisfarne Castle
"For the building exterior we had the scanner set on high, this gave us up to 125 million per scan, high quality photos with an average scan time of 8:30 minutes - very good considering the castle elevations we were capturing are elevated approximately 25 meters above us and 35 meters away."
Lee Chandler, Scansite
Lindisfarne Castle is a 16th-century castle located on Holy Island, near Berwick-upon-Tweed, Northumberland, England. Holy Island is most significantly known because it is the site of where the vikings first landed in Britain.
On behalf of the National Trust, Scansite were asked to 3D scan the external and internal of the castle, as the castle had undergone substantial regeneration works in 2016.
Read on as Lee Chandler from Scansite tells us more about the challenges faced on site:
"The first big hurdle to overcome was that the terrain of the site is challenging so positioning would be key to capturing the raised elevations of the castle."
Geo-referencing
GNSS positioning control was established around the site and this information relayed into the T10 tablet via Filed link. Then using the scanners laser point we were able to geo-reference and position the scanner.
Auto Calibration & Levelling
Another key aspect was levelling. Due to the uneven terrain, the X7 came into its own, each time we initiate a scan the scanner auto calibrates and auto levels using its built-in dual axis
compensator for automatic survey grade level compensation. This undoubtedly saved us time & gave us a significant amount of reassurance at every scan.
Number of points settings
We used all three settings for different scenarios, High, Standard and Low.
For the building exterior we had the scanner set on high, this gave us up to 125 million per scan, high quality photos with an average scan time of 8:30 minutes - very good considering the castle elevations we were capturing are elevated approximately 25 meters above us and 35 meters away.
Previously to capture this many points per scan would have taken approximately 20 minutes for each scan. For closer elevation scans and internals we set the scanner between Standard and Low, this gave us scan time between 5:30 & 2:30 minutes per scan with high quality images.
Weather resistance.
Holy Island is off the coast of Northumbria, and the castle is positioned at 35 meters above ground level - the island's most elevated point. The Castle is continuously battered by the high speed wind, rain and North Sea salt water. We scanned the castle at the beginning of October 2020 and faced such conditions.
The X7 stood firm whilst we stood next to it, whilst wiping the rainwater from the X7 every chance we could get. On a few occasions an extra strong gust of wind would slam into the X7 whilst scanning and it would stop the scan. This is an excellent safety feature of the X7, if the scanner receives a significant knock or a jolt it will stop the scan. Previously this would go unnoticed causing errors in the data and registration process down the line, but the X7 monitors its movement and will reject the scan if an error has occurred.
"Being able to register the data at the point of each completed scan is now a process we do not wish to do without."
Lee Chandler, Scansite
Onsite Registration
Now not only can we check that scans are aligning correctly but we can review to see if we need any extra scans to ensure we have captured the building in its entirety. Although we still export the data out to process via our office based workflows, we do occasionally refine and issue directly from the T10 tablet in .rcp or e57 format to hand over to the client before leaving site.