Photogrammetry and archaeology. Practical cases.

3D Techniques for use-wear analysis and technology studies in prehistory: Exploring a new field of application.

November 9th, 10th and 11th 2015

Photogrammetry and archaeology.

Practical cases.

1 2 3 Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Index

Photogrammetric recipe 12 tricks to capture photographic data.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Study cases 1

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Context.

- Cueva del Mirador, Atapuerca.

-

Cave with several burials.

Mix and superposition of bones and archaeological materials.

Challenge.

-

To document each fragment of the remains spatially.

To obtain Cartesian coordinates for each element.

Little room to work comfortably and with guarantees.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Solution.

-

Photogrammetric documentation.

Obtaining a georeferenced orthophotograph.

Incorporation of data into a GIS. Recovering the coordinates of each archaeological element electronically.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Context.

-

Peramola, Alt Urgell.

Private collection.

Group of 75 polished stone axes.

Challenge.

-

Exhaustive documentation of a large archaeological sample in a short period of time.

To ensure that the data obtained will be able to be used by other researchers.

To take advantage of the only chance the owner gives to study this material.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Solution.

-

Photogrammetric documentation / laser To obtain radiometric and geometric data.

To create a 3D model (digital surface model).

To generate sections, views, etc. for each archaeological element.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Context.

-

Berrias et Casteljau, Rh么ne-Alpes.

Archaeological dig in extension.

Irregular terrain.

Challenge.

-

To do a small topographical survey.

To document the area and the altitudinal variation of each stratigraphic deposit.

1

Study cases 1 To get the coordinates in impossible places.

Recording for posterity.

Does anybody know a topographer?

Solution.

-

Aerial photogrammetric documentation thanks to drones and posts.

To generate a digital model of the terrain.

To create an isometric map of altitudes.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Study cases 2

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Context.

-

Cemetery of Moros de Coll de Mu, Alt Urgell.

Archaeological site in a remote area.

Excavated anthropomorphic tombs in a very poor state of conservation.

Challenge.

-

To do a complete graphic recording of the structures with quality guarantees.

To document and preserve the state of conservation of the remains in a digital way.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Solution.

-

Aerial photogrammetric documentation thanks to drones.

To generate a digital model of the terrain.

To create an isometric map of altitudes.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Context.

-

Field 7 Roureda of La Margineda, Andorra.

Archaeological dig in extension of a deposit of Bronze Age remains.

Challenge.

-

-

To analyze the spatial spread of archaeological

evidence in the context of the site.

Several data integration.

The need for having shared digital models on which superimpose different layers of information.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Solution.

-

To get and process data in a similar way used with Geographic Information System.

-

Integration of data in a Geographic Information

-

To create a unique, multiscale, multilayer, digital model that can be shared with other experts from different fields to include their information.

System.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Context.

-

Archaeological site of La Roureda of La Margineda, Andorra.

Archaeological dig in extension of a large site of the Medieval period.

Challenge.

-

Detailed documentation of all the unearth architectural structures.

To draw all the walls (floor plan and profile) stone by stone.

Huge number of stony elements and overlapping system of walls.

2

Study cases 2 Without paper or pencil.

Data integration.

Drawing stone by stone.

Solution.

-

Aerial photogrammetry and on surface + 3D laser scanning.

Process of data.

Getting different 3D models.

Combination and mix.

3

Photogrammetric recipe 12 tricks to capture photographic data.

Photogrammetric recipe

3

Photogrammetric recipe 12 tricks to capture photographic data.

Maintain fixed focal length without changing the zoom, and disable auto focus. Try to focus the object of interest so that this focus allows you to make the maximum number of shots. If for some reason you have to work with several focus, take pictures in a sequential way without alternating focal points.

Increase the depth of field. If you increase the number f (you decrease the diameter of the diaphragm) images will be well-focused from short distances to infinity.

3

Photogrammetric recipe 12 tricks to capture photographic data.

Always work in RAW format. With this format you will be able to develop digital photos preserving as much information as possible.

Take multiple shots, preferably stereoscopic pictures (around the object) and a convergent photograph (also stereoscopic). Two photographs would be the minimum to restore any part of an object, but it is better to take three shots for each zone. Try to cover the visible range of the image as much as possible.

3

Photogrammetric recipe 12 tricks to capture photographic data.

Add photographs showing the context of the project to be able to see the ensemble of the patrimonial object from different points of view. The panoramic pictures are an excellent choice for this purpose.

Add some metric reference (like a tape measure in order to fix the scale). It is better if you can take a straightened picture, because like this you can fix the vertical. Ideally, several topographical supports are well-placed around all the surface of the photographed object.

3

Photogrammetric recipe 12 tricks to capture photographic data.

Work with the lowest ISO level as possible. Avoid working with high levels of ISO which turns the background of the picture noisy. It is recommended to use a tripod and a remote shutter release in order to get a clear picture with long time exposure.

Make a sketch of the capture and the pictures while the work is being done. Like this, you will quickly know where the pictures were taken from. It is much better if you can georeference the pictures (GPS, GLONASS‌).

3

Photogrammetric recipe 12 tricks to capture photographic data.

The more homogeneous is the illumination the faster and the more reliable the process of the data along with the equivalent points will be. Moreover, the result will be a continuous representation. It is better if you work early in the morning or in the evening. Take advantage of cloudy days. If that is not possible, it would be necessary to take several pictures with different times of exposure and to generate pictures with high dynamic range (HDR).

Add a color chart to those works needing a faithful reproduction of the radiometry of the object. There are different kinds of color charts in the market dependent on size and color gamut. If you do not have any color chart, add at least a white pattern to the pictures.

3

Photogrammetric recipe 12 tricks to capture photographic data.

Metadata. Include the necessary data in order to recognize the place where the work was done, when it was done, by whom and for whom. Also with which camera the picture was taken, with which lens, how many shots were taken, etc. Do not forget to add the calibration certificate of the camera if you have it, so you can use again the pictures for future projects.

Do not forget the accessories. Always remember the polarizing filters, the tripod, the remote shutter release, the color pattern, different lens, a flashlight, etc.

Research, Conservation and Spreading. Cultural and Natural Heritage of the Pyrenees. info@regirarocs.com www.regirarocs.com