# quick geometry modelling query

Hello,

A fairly basic question on geometry entry I think. When modelling geometry does it matter if
opaque (ie plastic) elements intersect? I am modelling using autocad. For example, say I am
modelling a 'waffle' type roof structure, to which a standard plastic material is to be added. I
have drawn all the beams going in one direction. For the beams cutting through this beam
perpendicularly, do you;

a; draw individual small beams between the existing beams (no intersection, but alot more geometry
description. does this do anything to calculation times?)

b; draw long beams cutting through the existing beams (much less geometry entry, but does the
intersection result in inaccuracy/redundancy somehow?)

c; does it matter?

in RwR p.59, the simple vase case, primitives are intersected together, such that the 'interior' of
the vase is not as in 'real life'. Given this, and as long as the exterior of the 'waffle' is
light tight, can I draw it with fewer but intersecting elements?

Many thanks, this mailing list has been a very useful learning resource,

Dan Lash
Sheffield Hallam University, UK.

octree is where intersection are handled...
so, I guess, should be fine;
however you will have to face with the 'famous' -ar paramether.... (RWR p.
555)
hope it helps...
pillo
oops!
giulio

···

-----Original Message-----
From: Daniel LASH(SED) [mailto:[email protected]]
Sent: 25 March 2004 16:20
To: [email protected]
Subject: [Radiance-general] quick geometry modelling query

Hello,

A fairly basic question on geometry entry I think. When modelling geometry
does it matter if
opaque (ie plastic) elements intersect? I am modelling using autocad. For
example, say I am
modelling a 'waffle' type roof structure, to which a standard plastic
material is to be added. I
have drawn all the beams going in one direction. For the beams cutting
through this beam
perpendicularly, do you;

a; draw individual small beams between the existing beams (no intersection,
but alot more geometry
description. does this do anything to calculation times?)

b; draw long beams cutting through the existing beams (much less geometry
entry, but does the
intersection result in inaccuracy/redundancy somehow?)

c; does it matter?

in RwR p.59, the simple vase case, primitives are intersected together, such
that the 'interior' of
the vase is not as in 'real life'. Given this, and as long as the exterior
of the 'waffle' is
light tight, can I draw it with fewer but intersecting elements?

Many thanks, this mailing list has been a very useful learning resource,

Dan Lash
Sheffield Hallam University, UK.

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In general, it shouldn't matter what's going on inside of an opaque object in Radiance if you are viewing it from the outside. It will probably be slightly faster if the geometry is simpler, all else being equal.

-G

···

From: "Daniel LASH(SED)" <[email protected]>
Date: March 25, 2004 8:19:48 AM PST

Hello,

A fairly basic question on geometry entry I think. When modelling geometry does it matter if
opaque (ie plastic) elements intersect? I am modelling using autocad. For example, say I am
modelling a 'waffle' type roof structure, to which a standard plastic material is to be added. I
have drawn all the beams going in one direction. For the beams cutting through this beam
perpendicularly, do you;

a; draw individual small beams between the existing beams (no intersection, but alot more geometry
description. does this do anything to calculation times?)

b; draw long beams cutting through the existing beams (much less geometry entry, but does the
intersection result in inaccuracy/redundancy somehow?)

c; does it matter?

in RwR p.59, the simple vase case, primitives are intersected together, such that the 'interior' of
the vase is not as in 'real life'. Given this, and as long as the exterior of the 'waffle' is
light tight, can I draw it with fewer but intersecting elements?

Many thanks, this mailing list has been a very useful learning resource,

Dan Lash
Sheffield Hallam University, UK.