the original
picture of the wall to draw
the un-warped
and scaled image
the computer-generated
drawing
A Simple Solution to Traditional
Drawing and Photographic Recording of Archaeological Features;
a joint work with Amanda
Henry.
The search for novel methods to record excavated features in archaeological
sites has led to the invention or adaptation of many technological tools, ranging
from photogrammetry to 3D reconstruction. Unfortunately, many of these methods
require more training, more preparation and more expense than the traditional
method of handing a measuring tape, plumb bob and graph paper to a volunteer.
While the traditional method is the most convenient for many field directors,
it is often subject to inaccuracy and can be very time consuming.
In contrast to both the traditional and the more expensive methods, we have developed a simple protocol using a computer program which can process digital photographs to remove parallax problems and find the edges (e.g. boundaries between blocks in a wall) in the resulting image. The end result is a properly scaled, un-warped image, with or without highlighted edges, which can be printed or stored electronically. This method requires the time of only one operator with minimal training in digital photography and a brief introduction to the program. It has been successfully employed at the Brown University Excavation of the Petra Great Temple, Jordan.
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the original
picture of the wall to draw
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the un-warped
and scaled image
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the computer-generated
drawing
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Acknowledgements
This work has been realized within the SHAPE
Lab at Brown University, under the NSF grants ITR # 0205477 and KDI #BCS-9980091.
We would like to thank Martha S. Joukowsky, Artemis Joukowsky, David B. Cooper,
the SHAPE Lab, Brown University, Andrew Willis, Sara Reid and the 2002 Petra
team, for their help and support at different stages of the project.
Further information
Wall Drawer: A Simple Solution to Traditional Drawing and Photographic
Recording of Archaeological Features - P. L. Bazin and A. Henry, submited
to the Journal of Field Archaeology.
The WallDrawer program has been released on SourceForge.net. Both source code (in JAVA) and executables (for any JAVA-enabled platform) are available as free software under the Gnu Public License:
http://sourceforge.net/projects/walldrawer/
(using Winzip). The Wall
Drawer program is the file walldrawer.exe (on Windows).(double-click on the program icon). A command line window and
the regular window of the program should appear (the command line window
just displays extra information).(File -> Preferences) and save them (File ->
Save Preferences). A text file walldrawer-prefs.txt should appear in
the program directory. Important settings to fix are the desired output scale
(1:10, 1:20, ...) and the resolution of your printer
(warning! if you have a very fine printer resolution like 1200dpi, the images
will be huge. You can adapt the resolution of the printer too (I recommend
300dpi), so the images will remain of decent size in pixels. Also note that
the output drawing must fit on the paper size used in the printer, i.e. mostly
letter or tabloid).
(Help menu).(File -> Open Image).(Processing -> Select Region). By default,
the entire image is selected.(Un-warping -> Draw Checkerboard, then
use the mouse to drag the outline on the checkerboard image).(Un-warping
-> Un-warp Image). The new image is automatically scaled in the
process.(Un-warping
-> Draw Edges).(Processing -> Magnify to darken the edges, Threshold
to remove weak edges, Thicken to broaden the edges). At any time, the
original, un-warped, edge and processed image are available (Display
menu) and can be saved (File -> Save will save the displayed
image).(Ruler menu)
and print the edges to obtain a drawing at the specified scale.07 - 03 : Initial release.