Thanks Professor Bill,
I’m currently working with ‘continuity lines’ in my Msc. It’s looks very
similar to the ‘linear strokes’ proposed by Thomson in the last
symposium. These ‘continuity lines’ (many aggregated axial lines)
apparently improve the ‘differentiation’ of the system but I couldn’t
capture it with the difference factor.
Reading what you’ve written, I think it may work with a set of
representative values of the system, not only the maximum and minimum
integration values, but maybe a set of ‘mean cores’, reducing the system
from ‘k lines’ to 4 or 10 representative values.
Now, I’m working hard to finish my Msc. I will test it later. I agree
with you, the difference factor has potential.
<>Thanks again,
Lucas Figueiredo
MDU – UFPE – Brasil
>The idea of difference factor was to try to measure the degree of
>difference between the integration values of, say, a everyday living room,
>a guest reception room and a kitchen in the context of the whole house
>which of course was made up up many more spaces.. We needed some index of
>the degree to which main functions were spatially differentiated, since in
>some cases the differences seemed to be small and in others large, and this
>seems to be an important feature of the house. If you have a large number
>of spaces, then of course the spread of values, can be indexed by measures
>like standard deviation, but this won't work for just three, or even a
>small number of spaces, especially as in some cases, one space was much
>more integrated or segregated than others. Difference factor can of course
>be applied to the minimum, maximum and mean integration values of a system
>with a large number of spaces (in which case it would often tell a similar
>story to standard deviation), and then to selections of the main functional
>spaces, and this would enable you to see how much of the overall
>differentiation in the system was taken up by functional spaces, as opposed
>to, say, the difference between transitions spaces like hallways and
>functional spaces. The measure is far from perfect, but in most
>circumstances it seems to give a rought indication of what it is intended
>to measure.
>
>We used to use entropy based measures on axial maps for exactly the same
>reason: to try to measure the degree of difference between one or a few
>spaces and others. Again, what we were trying to get at was that in some
>cities one or two streets were much more integrated than others, while in
>others differences were more marginal. As I recall (it was back in the
>eighties) we used to normalise the measure against the hatural number
>system, since this maps on to the depths of space from a root in a unlinear
>sequence. Eventually the measure fell out of use because it did not give
>very interesting results. We need to go back over some of this and try to
>reconstruct where we got to. I sense there is something interesting here,
>but at the time we never found any results which were interesting enough to
>publish. Perhaps its time to look at it again. - Bill
>
>
>
>
>>Hello everyone,
>>
>>Iíve got some questions about the ëdifference factorí. In my unique
>>reference, Hiller and his colleagues proposed it for a system with three
>>spaces only.
>>
>>*Hillier, Bill; Hanson, Julienne e H. Graham. ëIdeas are in Things: An
>>Application of the Space Syntax Method to Discovering House Genotypesí.
>>Environment and Planning B: Planning and Design 14, 1987, pp 363-385*
>>
>>This measure is based in the entropy, and its maximum value is ln(k) for
>>a system with k lines.
>>
>>But, why doesnít the minimum value is zero? Or, at last, a value
>>generated by the ëlinear graphí ñ the maximum asymmetry ?
>>
>>o ----- o ----- o ----- o ----- o
>>
>>Iíve modified the formula to n spaces and tested it in some axial maps.
>>Iíve got results close to the maximum value for any map Iíve tested.
>>
>>Anyone has ever used the difference factor for axial maps?
>>
>>Thanks in advance,
>>
>>Lucas Figueiredo
>>MDU - UFPE - Brasil
>>
>>
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