Getting technical - Light Detection and Ranging (LiDAR) in Petworth Park

As part of the Petworth Park Archaeology Project we have been looking at a range of different images of the park in order to identify archaeological features.  This has included historic maps and aerial photography, and also LiDAR data.

LiDAR is a form of airborne laser scanning which allows us to build up a 3D model of the landscape. Pulses of infra-red light are scanned across the landscape from an aircraft – the pulses reflect off the ground and are received by sensors on the plane which calculate how long it took for the pulses to return.  Using this information, and knowing the precise location of the plane from GPS we can calculate the position in the world where the pulse hit the ground (±15cm) and represent it as a point in three dimensional space - the sensors can collect up to 100,000 of these points every second.

This gives us millions of point measurements across the landscape – like a blanket of snow.  We can then stitch these points together to create an accurate 3D model of the landscape which we can manipulate and interrogate in all sorts of ways to identify and measure the humps and bumps which might represent archaeological features.

The video below shows a form of processing called Polynomial Texture Mapping.  This allows us to place an artificial light source (a virtual sun) above the landscape and move it around to draw out features through the play of light and shadow.

Often these features are very difficult to see on the ground because they are so slight, or due to vegetation cover. The dense beams of infrared light used for LiDAR data, however, are able to penetrate through vegetation, allowing us to ‘filter’ out the trees and taller plants to look at the landscape underneath.

An aerial photo (left), ‘unfiltered’ lidar (centre) and ‘filtered’ lidar (right) for Arbour Hill in Petworth Park, possibly the site of Henry VIII’s banqueting house.  By filtering out the vegetation, the lidar allows us to see the square earthwork enclosure and central mound (circled in red)

As part of the Petworth Park Archaeology Project, throughout December and January we will be ‘ground-truthing’ the sites we identify in the LiDAR data, historic maps and aerial images, photographing and recording them.  This will help to inform the later stages of the project in 2013 which will see volunteer Assistant Archaeologists undertaking geophysics and excavation of specific features.

If you’re interested in volunteering with the project, or want to find out more, get in touch with susan.rhodes@nationaltrust.org.uk or call 01798345525, and keep an eye out for more posts in the future.

Servants' stories

So far we’ve heard form Phyllis, an under-maid who worked at Petworth in the 1930s and Dorothy whose father was a scullery man and this week we’ve found an extract from Horace Arnold remembering his time as a Junior Footman.

‘I started work for Lord Leconfield in 1929 at his London home in Bryanston Square. He did have another house in London but like many people of his social set he rented a house for the ‘season’. The salary was £30 a year and after nine months in London, I came down to Petworth. I was junior footman, sometimes referred to as stewards’ room boy. My basic task was to attend to the senior staff, an elite among the servants, Mr Wickham the butler, Mrs Cownley the housekeeper, Mr Coddington, his lordship’s valet and Florence Roper the head housemaid. Whether in London or Petworth my job was to take care of their meals and their dining room. I was only sixteen or seventeen. I’d be up at 7.30am to start the fire; I wore clerical grey morning suite but for this early part of the day an old worn one, my ‘scruffs’ as I called it. The breakfast was always cooked and I collected from the kitchen, the food was excellent.’

‘The chef was a woman at this time but I also seem to recall a Belgian chef but maybe he was only brought in for special occasions. The senior staff had a set menu, which I would need to know in advance so I could lay up the table, I would serve in formal manner at table, over the left shoulder. Dinner for the steward’s room would be eaten before dinner in the main house. When there were guests in any number I would go over to the house to help. The meal would be served in the Square Dining Room or if it were a very large party it would be in the Carved Room. Full livery uniform was worn by the footmen, - a yellow and blue stripped waistcoat, white shirt front, jacket of navy blue with silver buttons, smooth ‘doe-skin’ trousers and black patent leather shoes with a buckle.’

Here’s a ‘servant’ ready to serve dinner at our The 3rd Earl’s Christmas event last year.

The deer rut

It's pretty much over now, and the sounds of antlers clashing and the calls of the males (bucks) can no longer be heard across the park as the bucks in our herd of fallow deer try to assert their dominance over each other. It’s an amazing sight, and here are some of the great pictures we’ve been sent…

 Tim Cook

 

 Dave Vadis via Twitter

                                           Film and photos from Tim Holyoake via Facebook

During the rut the most dominant buck will take up position of the centre of the rut surrounded by females (does), he’ll then work to keep his position and group of does as other bucks challenge him. Not all the bucks will challenge, some take up positions further out and simply wait to see if does move toward them, and other bucks will break out into smaller groups.

It can look brutal, but they’re aiming to show their strength rather than cause injury. You might also see them walking in parallel to size each other up before rutting and often one will decide to back down if the other looks a lot bigger!

If you’re going to watch the deer, make sure to give them plenty of space and please keep dogs on leads.

Digging up the past…

Hello everybody!  There’s exciting things afoot (and under foot) at Petworth this year.  My name's Tom and I’m the National Trust’s archaeologist for West Sussex and the South Downs.  This year I feel very lucky that alongside my other work I will be taking a closer look at Petworth Park, unearthing the secrets and stories that lie preserved in the landscape and beneath the ground – and I’d like you to help me do it! I’m hoping there will be lots of opportunities for anyone who is interested to get involved.  But first, a bit more about Petworth, and why we are doing this in the first place… 

Petworth Park is very different from the original park which was created at least 750 years ago. Today the park is made up of gentle rolling slopes, tranquil shady glades of trees and grand vistas.  It looks natural but in fact everything we see is the result of careful crafting and moulding of the landscape over hundreds of years, to fit the fashions of the times and styles of the owners.  At one time or another, the park has included canals and formal gardens, rampart terraces and monumental stables, Henry VIII’s banqueting hall and a Second World War military camp – not to mention the original manor house! 

 A bird's eye view of Petworth Park, can you image a stable block and formal gardens stretching as far as the lake?

 

There are so many questions that remain to be answered, so many discoveries just waiting to be made. Over the next year we will be examining historic maps and documents, looking beneath the ground with geophysics and excavation and searching for traces and clues in the landscape to uncover the physical evidence of Petworth’s hidden past.

An unusual thank you

We’re always grateful for the kind letters, emails, tweets and comments we receive from visitors and usually these relate to the great day they’ve had with us, but this week it was a thank you of a slightly different nature...

Yesterday we received some lovely cakes and a card from a member of the public, not praising an enjoyable day out, but for helping her when she suddenly became ill whilst driving and pulled into our Car Park.

  

‘To the ladies and gentlemen of Petworth House ticket office. Thank you all so much for your help and kindness last Sunday. I apologise for the disruption but am greatly appreciative of your assistance. I would also like to say an extra big thank you to your first aid officer (Geoff) for holding my hand throughout!’

We’re so proud of the quick action and first aid skills of our Visitor Reception team who looked after her and called an ambulance, whilst dealing with the large number of visitors we get on a weekend. We’re also proud that both our and the National Trust’s reputation meant she knew we’d be a safe place to stop for help.

Artist still in residence

Hi all, Samuel here. I promised you an update on our artist in residence, Wendy Norris who is currently copying a painting in the Marble Hall, and here it is… 

(you can find out all about the project and see the first pictures here)

Isn’t it coming along nicely? I did offer to help out and do a few strategically placed paw prints, but apparently that’s not quite the look Stowe School are after. I also suggested it could be improved with the addition of a handsome spaniel sitting next to George Grenville, but sadly my creative genius isn’t always appreciated.

                                                                

You can see how the layers of paint have built up and are now far more like the original. It’s also a great chance to see how the original painting might have looked over 200 years ago, before the pigments had darkened and George Grenville started looking a bit grey and ghostly.

Servants' stories

In the second instalment of our ‘Servants’ stories’ series, we hear from Dorothy Digby whose father Fred Baigent was a scullery man at Petworth House in the 1930s.

‘Dad would peel all the staff potatoes and carrots. Another job of his was to make ice cream using a big wooden bucket with a handle. The chef would prepare the mixture, put it into a cylinder in the centre of the bucket and cram ice and saltpetre round it. He would then let it stand for three hours, turning the handle occasionally. After the ice cream had been made it would be covered with a stiff meringue… then Dad would bring in the salamander, a long iron pole with a metal square set diagonally on its head. He’d get the metal square hot in the fire and hold it over the meringue. It was desperately hot work for him but the result was –Baked Alaska!’

Making the ice cream would have looked something like this...

 ...ice cream being made in the Historic Kitchens last year as part of our monthly ‘What’s Cooking?’ event.