David Wheatley D.W.Wheatley at
Mon Jun 7 05:51:48 EDT 1999


I believe that this was written by Mark Lake, formerly of Reading University
(England) and now at the Institute of Archaeology, University of London. I am
not sure that the code for r.cva has ever been made public but I will copy this
email to Mark who may want to respond directly.

While working for Reading's 'MAGICAL' project and I recall that he spoke at
conferences about a programme called r.cva, which stands for 'Cumulative
Viewshed Analysis'. My interest in this is that I defined CVA in two papers in
'93 and '96 (references below - apologies for wanton self-publicism...) and I
know that a number of other archaeologists have an interest in this area (for
example, Vince Gaffney of Birmingham University, Mark Gillings and Clive Ruggles
of Leicester University).

You may already realise there remain methodological problems with CVA as I
published it that have been pointed out by other researchers. Notable among
these are that it is very prone to 'edge effects' and that it assumes
reciprocity of view-from and view-to (which is not appropriate where the viewer
height is non-negligible in relation to the distance of view). However, it
remains the only published method of statistically testing for intervisibility
among a group of locations.

David Wheatley
University of Southampton

Wheatley DW 1996 "The use of GIS to understand regional variation in earlier
    Neolithic Wessex" in Machener H (Ed) 'New methods old problems' Occasional
    Paper No23 of the Centre for Archaeological Investigations, Southern 
    Illinois University at Carbondale pp75-103

Wheatley DW 1993 "A view to a Hill ..." in Lock G and Stancic Z 'Archaeology 
    and GIS: a European Perspective" Taylor & Francis.

Francisco Estrada Belli wrote:
> Dear Friends
> To all of you who have been doing viewshed analysis and to programmers at
> large:
> Has anyone seen a binary or source code for a cumulative viewshed program
> called r.cva? It was mentioned in a recent "Journal of Archaeological
> Science" (11/1998).
> No response from the article's authors so far, so I wonder if someone else
> has come across it and wouldn't mind sharing it with me.
> Thank you,
> Francisco

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