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I need to calculate the surface (m2) of external walls of all the buildings in a town. By external walls I mean all the walls of a building or parts of a wall which are not in contact with another building. I have a 2D shapefile of polygons with the cadastral footprint of the buildings, which includes information of the building’s height in the attribute table.

I don’t really know how can I do it… My idea is to convert the 2D file to 3D and use the 3D shapefile to distinguish the external walls from the shared walls (parts of a building that are shared with other buildings) of all buildings, and from there, calculate the total area but I’m not sure whether this can be done with ArcScene.

Anybody knows how could it be done and if there is an automate way to do it?

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INPUTS: enter image description here

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PROCESS:

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  1. Join summary table to S_JOIN using line id
  2. Select not shared walls using

    "SUM_ST.FIRST_BLDI" = "SUM_ST.LAST_BLDID"

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Remove join and export selection to new dataset called NOT_SHARED. Switch selection and export it to SHARED

Join summary table to SHARED, select walls that are higher than neighbour:

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Calculate H using:

[SHARED.H] - [SUM_ST.MIN_H]

Merge NOT_SHARED with selected SHARED:

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RESULT enter image description here

Manipulate table of ALLWALLS as you wish, e.g. summarise L*H per building

The process is much more simple as it looks. The key features here is converting polygons to lines (so called arcs), keeping in mind that they are a divides between 2 polygon max and using min(H) in statistics table.

Note: Solution is not going to work with overlapping polygons.

  • Hi, thanks for your answer. More or less. This would be part of what I need. Once I have obtained this (which I don't really know how to do it) I need to get the actual surface of each wall that is external. For example, the wall with length =100 shared by BLD_2 and BLD_3 is partially external: the external surface of this wall would be (length) 100 x (height) 3 (which is 8-5). Instead, BLD_2 wall with length 50 would have a surface = 50 x 8 (height) – Adri Dec 11 '15 at 15:15
  • W in above is total area of external walls. H building height – FelixIP Dec 11 '15 at 18:47

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