Betweenness in a symmetrical grid

[Henrique Lorea Leite]

Hi,

I'm a urban planning student from Brazil and I've been testing the UNA Toolbox. I'm using a symmetrical grid, expecting to get symmetrical or constant values as results for the Centrality Measures. For some reason, this is not the case for the betweenness values, as shown in the picture below.

I've tried it with grids of different sizes and used junctions and midpoints as input buildings. For the impedance, I'm using length, which has the same value for all the features.

Am I missing anything so that I'm not getting the results I was expecting for the betweenness measures?

Congratulations for the amazing work and thanks in advance for your attention.

Best,

Henrique

[Andres]

Hi Henrique,

this is an elegant application. I know that GIS network analyst can be quite picky to even tiny discrepancies in route distances and favour routes that are even very slightly shorter than others. Could you please first check if the grid you have is a) uniform in deistances to a decimal point precision level and 2) is uniformly connected at every node (no topology issues)? You can check the latter by just manually routing different shortest paths over the network or doing service areas. Technically, if the routes are exactly the same length, then our Betweenness algorithm should use all equidistant routes and assign each a partial probability and you should get symmetric results. I see that your symmetry does appear across the horizontal axis and not the vertical axis.

Andres