[esp-r] Re: defining general polygon obstructions

[Jon Hand]

The intended definition of general polygon obstructions is to initially create
a standard obstruction in prj and then use the in-built facility to convert this
to a general polygon structure and the to edit the vertices.  The order
of the surfaces and edges of polygons generated via this approach is
what the shading module is looking for and tested for.

The limitations are 6 sides to the obstruction.  The user is assumed
to create surfaces which are flat (there is no interface check to force
a flat surface when you are editing polygons).  General polygon
obstructions are only available with the newer version geometry files.

There are examples of various obstruction types in the exemplar
model (folder) simple bld_simple_shd.cfg and in the zone geometry file
simple/zones/reception_shd.geo

-Jon Hand
________________________________________
From: Lomanowski, Bartosz [Bartosz.Lomanowski at NRCan-RNCan.gc.ca]
Sent: 05 May 2010 14:21
To: Jon Hand; esp-r at lists.strath.ac.uk
Subject: defining general polygon obstructions

A question about general polygon obstructions (type 'obsp'):

>From reading the help info I understand that such a polygon must have flat surfaces. Are there any other constraints in defining such an obstruction? Is there a particular order for defining the vertices such as the anti-clockwise rule? Does it matter whether vertices 1-2-3-4 make up the bottom or the top surface?

I ran a quick comparison of two different definitions of the same obstruction ( see attached jpeg ). There were differences on the order of 0.05 in the insolation and shading factors. Which of these is deemed correct?

Thanks,
Bart

NRCan, Canada