Dave Green - Cultural Heritage Photographer, Artist and Educator

December 8, 2020

Improvements in 3-D virtual modelmaking

I’ve continued my exploration of 3-D virtual modelmaking, endeavouring to forever improve my practice. Working at the Burton Art Gallery some weeks ago I was unable to include the bases of some of the big harvest jugs and delicately decorated puzzle jugs because turning them upside down, on a turntable, would have been too dangerous because their rims were very small in comparison to the weight of their bodies, they were uneven or extremely fragile. Simply lying them on the side did not work because their smooth rounded surfaces would not stay in one place and they would always dangerously wobble!

In my studio I found that using a rubber ring in the centre of the turntable would support a spherical object very safely. At first, I tried with rubber rings or rubber washers that I had in my toolbox. The largest of these, probably from a plumbing waste pipe assembly, worked very well with some jugs that I had at hand. I would need something bigger though for the harvest jugs that I intended to photograph. We were in lockdown so I searched various online shops with little joy. I had expected DIY shops just to be selling rubber washers as part of a set for a specific use. However, B&Q had a couple of very useful items; A 2-inch cistern coupling and something similar for toilet repair. The black pure rubber items were perfect for holding these valuable delicate jugs in place on a moving turntable.

The quantity and brightness of light for photogrammetry is really important because it is necessary for closing the lens aperture down and so helps in producing a well-focused object; this in turn makes a better 3D Model with a background easier to mask out. With this in mind I had invested in a new pair of 1000-watt studio flash heads.

Another day-shoot was organised for the Burton, just before they opened again to the public. I was keen to try out my new process on the historic jugs that had been most problematic last time, and to use my new lights. I constructed a studio with a jet black background and placed my heavyweight automatic turntable on the sturdy table. The 1000 Watt studio flash heads were directed towards the white ceiling to ensure a very soft and diffused overhead light. A small reflector threw some light back from the camera view into the shadow areas underneath the jug. Another first for this shoot was syncing my heavyweight turntable, which could take loads of up to 40kg, with my Syrp Genie Mini; which was itself synced with the camera and studio flash. The first object, a large harvest jug, was placed on the rubber washer on the turntable, and it was beautifully balanced as I had hoped. A QP card was used to ensure correct white balance. A full rotation off the jug was controlled, via a Bluetooth connection, by my Syrp iPad app. The process seemed to work seamlessly. The only problem I had was that the new flash heads tended to overheat after prolonged continuous use on full power. This was overcome by allowing them to cool every so often.

Ceres Harvest Jug 1795
by Dave Green

280 photographs of the Harvest Jug, shot in RAW, were transferred to my computer. I performed basic adjustments in Lightroom, white balance and exposure, then exported the files as HQ Tiffs to a folder. These were fed into Metashape photogrammetry software to create the 3-D virtual model. A decimated version was then uploaded to the Sketchfab platform.

The process was repeated with a Puzzle Jug, 212 photographs were taken in a similar fashion. The computer processing time required for the virtual model making was a good 12 hours; aligning the photographs, building the dense cloud, constructing the mesh and finally adding the texture.

Camera positions

Cleaning the background

Most of this was automated and could be left over night with the monitor turned off. However, with careful selection, it ought to be possible to half the time by halving the number of photographs.

Addition: Since writing this post I have gone through the Metashape construction process with almost halved the number of photographs, 147, and made an almost identical 3D Model. See it here Model from 147 images The first stages in Metashape, Aligning Photos and Building the Dense Cloud were still very long, but there was less background to clean up and the latter stages were considerably faster. Compare the 2 models and see if you can make out any differences.

I started blogging about this part of my professional arts practice in May. If you’ve got this far down the page you might also be interested in my previous blogposts on the subject; Photogrammetry and 3D Models of Museum Objects

October 23, 2020

Erard Grand Piano Paper Washers part 1

Everyone remembers the last job they finished before lockdown in March 2020. I had been working on mine for over seven months and I was desperate to bring it to a close with a hiking trip to along the French and Spanish coast booked for early March. I never expected it to take half a year, I never expected it to start at all. But what would you do if you received an unsolicited email out of the blue starting:

Hello,
I was referred to you by AHFAP.
I live in Houston, Texas

The email went on to describe at lengths about how an old Erard grand piano had been bought and restored and how the restorer had discovered the original balance washers underneath the keys which had writing on them, looking like they had been cut out of a newspaper. AHFAP is the Association of Historical and Fine Art Photographers of which I am a member. The email concluded with the interesting paragraph as follows:

I have attached just enough pictures to hopefully spark your interest. I only know AHFAP by reputation and I am neither a photographer nor an artist, but it seemed to me that there is a project here in the making. My original idea was to simply do micro-photography of some of the more interesting pieces and enlarge them to poster size. But after spending some time on-line I thought it worth the time and effort to ask someone with a creative and photographic background to give this some thought.
Would you be interested or do you know someone who might?

The email signature was that of a major partner in an international law firm. I was naturally suspicious, assuming this was some kind of scam or hoax or simply mistaken identity and yet I was also intrigued. I weighed up the pros and cons and could see little reason in ignoring it, so I responded enthusiastically looking for a little more information.

What followed was much email communication and the project became a commission. A day rate was agreed but a final outcome, end date and total budget was kept open. I could see that I was going to have to take more of a collaborative fine art approach to this commission than I would for a commercial job. The piano had been made in London by The French company Erard In the early 1860s, it had been bought almost a year ago from a seller in Italy where it had been sent to England for restoration. It was currently on a slow sea journey across the Atlantic to Texas. The newspaper washers, however, were already in Texas.

The photograph below, taken by the piano restorer, is an example of what was to be an interesting real life crime story from 1861.

My client had already done a little research to try and determine what source the washers had been cut from. Using the British Newspaper Archive online he had been able to search for the legible words on a washer using an approximate year date and had found some of the stories associated with the articles that they had been cut from. The precise source of these stories was to become a major part of this project and started with this story discovered through the British Newspaper Archive from “The Morning Advertiser,” February 7, 1861.

Three days after the first contact I included this paragraph in an email that I sent:

I’m sure you will have some kind of budget in mind and perhaps the best way to proceed, once I have the washers in my studio and I am able to make some preliminary sketch work; is to enable me a limited timescale to produce something that you are able to see, and therefore we are able to discuss. I have been reading through your emails again and some of the words that you have written are already inspiring some ideas: I’m interested that this incredibly highly crafted grand piano needed something to bring the keys to a perfect level, and that thing was a simple paper thin washer, cut with a pair of scissors from a London newspaper, which happened to be lying about in the studio. There seems to be something profound in that! I’m also interested in the two-sided nature of these newspaper washers; it may be appropriate to photograph them so that both sides appear in the same image as light is diffused through the paper.

I was going to be opening my studio up for public visits in late September so I organised the delivery of the washers so that I would have them to work on for that time. I was sent some details about the piano restorer in Northumberland with a link to a blog he had written all about restoring this specific piano: AA Piano Tuners blog

On the 13th of September I received a large knock at the door and a box was delivered via FedEx containing the washers.

Erard Grand Piano Paper Washers part 2

July 14, 2020

3D Models of Museum Objects

Increased demand for access to museum collections is driving a trend toward object digitisation. This can only increase more as we move to a new world of restricted physical access. Three dimensional (3D) digital interactive models provide researchers with rapid on-line access and also enables multiple people to examine the same model simultaneously.

Accurate 3D models can be used for research & conservation, online exhibitions & interaction, licensing exact 3D digital copies to other museums, public engagement, making exact physical replicas of artefacts (through 3D printing), creating merchandise and 3D digital archiving of collections.

Daniel Pett, Senior Digital Humanities Manager at the British Museum considers 3D models “…a natural extension of museum object documentation. There is a clear progression from line drawing to photography, and now to 3D representations which can be audio described, annotated, reused and embedded. There is also the potential for them to be monetised, which could potentially create a valuable income stream to fund some of the Museum’s work.”

Gallery of Cultural Heritage models on Sketchfab

Some of the world’s biggest museums like the Smithsonian and the British Museum have been leading the way using huge, inhouse, dedicated photogrammetry studios to record their objects three dimensionally.

I have been making comparative models with a highly portable and unobtrusive kit, ideal for working in smaller collections where space is at a premium. The other big advantage of portability is that valuable and fragile museum objects don’t have to leave the collection to be recorded.

There are some limitations on the type of object that can be made into a 3D model for example a feather could not work because it is too translucent, a chrome sculpture would be too reflective and some objects might be too large to photograph from all angles. However, if a 3D interactive model is impossible It would still be possible to make a 3D rotating model as an animated GIF or video.

May 14, 2020

Photogrammetry

I’ve been keeping myself busy during coronavirus lockdown, learning to make 3D (three dimensional) models. It’s an outcome of Photogrammetry, the science of making measurements from photographs. The input is the photographs, and the output could be a map, a drawing, a measurement, or in this case a 3D model of a real object or scene. The YouTube videos demonstrating how to do this usually use something like a stone to photograph I make 3D. I decided to set myself a far more complicated challenge which was photographing the Monterey Cypress seedpods In the interactive box below, go ahead and make it full screen, you’ll get a better idea of what it looks like.

This seemed like a natural progression from my constructed images, where I was making photographs of from up to 200 separate photographs, and from my work for ArtUK photographing sculpture in various museums and other cultural institutions within the South West region. This 3D Image is made from 400 separate photographs all taken of The Monterey Cypress seedpods in my studio using flash lighting and an automated turntable. The images were then constructed together using Agisoft Metashape software, which took days but hopefully this will get quicker!

My model is held on a platform website called Sketchfab, the equivalent of YouTube for 3D models. Is the largest international platform for cultural heritage 3D online, and it is used by institutions like the British Museum and the Science Museum etc.

I am expecting that the single image type of documentation that I’ve been used to photographing museum objects will become a thing of the past as 3D models take their place. They can give a virtual viewer a far greater understanding of what an object is actually is like, and there is the ability to zoom in and move around an object just like have you would want to in a physical museum.

I’m looking forward to making a 3D model of have something made of clay next. I might try a complete pot or maybe just a sherd or fragment from Bideford’s rich Elizabethan past.

Monterey Cypress seedpods still image

July 2, 2019

Earth Photo 2019

“You have to be in it to win it” – how many times do you say that to yourself and so put time, effort and finance into a project and nothing comes of it? But then another well-known saying comes to mind “all things come to those who wait”…. Well my good artist friend Rosie Burns tipped me off on a competition, leading to an exhibition, which she suggested I should enter as she felt it was perfect for the body of photographs I was working on. It was Earth Photo 2019 organised by Parker Harris and with the biggest sponsors/stakeholders being the Royal Geographical Society and also Forestry England.

I felt the wild woodland I have been immersing myself in over the last couple of years in North Devon might be appreciated by Forestry England and that my exploratory way of working might turn a few heads in the RGS who will be used to following the exploits of world travellers exploring similar terrain far from civilisation.

I was delighted to have 3 images selected for the exhibition from the 10 that I had submitted to it. But ecstatic that my photograph of an old hedge won the category Changing Forests!

Coincidently I had planned a photo trip back to Dolton for the day after the private view. I re-visited the location of the now ‘famous’ (in your dreams Dave) hedge because I was curious now to see what kind of tree it had become. In the warm light of day it was curious to see just how un-photogenic it was. Even close up it was hard to say just what had attracted me so in April of last year. Most of the old hedge was hazel but interestingly there was one branch of hawthorn too!

The exhibition Earth Photo 2019 opens on Saturday 6th July at the Royal Geographical Society and simultaneously at Fineshade Woods in Northants. The photographs and films are amazing so go and see it if you can: selected images for Earth Photo 2019