Recently, on the 17th April, Dr Tim Dennis of the Colchester Archaeological Group sent Trust director Philip a great new image of a modified Lidar model of Colchester town centre. Dr Dennis generated the image using open source data and his own software. This is a brand-new image of the physical geography of Colchester town centre, modified by centuries of human activity, and it contributes a lot to our understanding of the ancient historic environment.
The Trust uses Lidar, totalstation, Googlearth, etc, among our research tools. Dr Dennis’ model shows Colchester in detail now, and why the fortress, town, castle, Roman circus, and the old Colchester garrison were built where they were/are (precisely sited).
The image/model shows the physical geography of Colchester, with the contours at 2-metre intervals – black indicates the lowest depth and white the highest height… You can see the line of the Roman town wall very clearly, as well as the River Colne, the two railway lines, two roundabouts, the area of highest ground within the walls where the Roman fortress stood, and the plateau to the south of the town which includes the site of the Roman circus and the old Colchester garrison – including the Trust’s HQ and Roman circus visitor centre! – ] and, to the south of that, the modern rectangular sports pitch belonging to the new Colchester garrison. The castle bank and ditch are also clearly visible within the town wall. The Roman town was, of course, built on a hill (white) which was defined to the north by the valley (very dark greys) of the River Colne. Sheepen Road, the Maldon Road, Butt Road, Southway, Magdalen Street, the Mersea Road and Brook Street are also visible. Within the town wall, you can see the streets of North Hill, Maidenburgh Street and East Hill.
Dr Dennis says that ‘… The picture processing is my own software, as is the point-cloud model (same program) on Sketchfab. I’m planning to redo the 3D model at higher resolution – the current version is a test at 2m/pixel to see if it would work… The precise coordinates of the SW corner are 598684, 224744 (TL9868424744) …’.
Lidar (Light Detection and Ranging) is – ‘… LiDAR, or 3D laser scanning, was conceived in the 1960s for submarine detection from aircraft and early models were used successfully in the early 1970’s in the US, Canada and Australia. Over the past ten years there has been a proliferation in the use of LiDAR sensors in the United Kingdom, with several regularly used in both airborne and ground surveying. This has been accompanied by an increase in the awareness and understanding of LiDAR in previously unrelated industries as the application of LiDAR has been adopted …
Ground-based LiDAR systems are very similar, only that an IMU is not required as the LiDAR is usually mounted on a tripod which the LiDAR sensor rotates 360 degress around. The pulsed laser beam is reflected from objects such as building fronts, lamp posts, vegetation, cars and even people.
The return pulses are recorded and the distance between the sensor and the object is calculated.
The data produced is in a ‘point cloud’ format, which is a 3-dimensional array of points, each having x, y and z positions relative to a chosen coordinate system …’ – at http://lidar-uk.com/what-is-lidar/
The image/model has been created by Dr Dennis using his own software, from data published online by Open Government?? at/the source for the model is http://www.geostore.com/environment-agency/survey.html#/survey?grid=TL92 or https://data.gov.uk/ . The Open Government Licence is published online at https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ . The source data has been used under the Open Government Licence [need to find required credit]. Many thanks to Dr Dennis for sending the image/model. ‘… Survey Open Data is managed by the Environment Agency and its contractor Airbus …’.
The images show the new model of Colchester created by Dr Tim Dennis (above), and (below), a plan of Roman Colchester from the Trust’s Colchester Archaeological Report or CAR 6: Excavations at Culver Street, Gilberd School and other sites in Colchester (1992), and a painting by artist Peter Froste of the walled Roman town with the Roman circus in the late 2nd century AD, based on archaeological evidence from excavations conducted by the Trust (this is currently on display at the Roman circus visitor centre in our archaeological art exhibition (until the 30th June ’18).
The scale model of Roman Colchester town centre which is currently being constructed here at the Roman circus visitor centre –