Strange Glowing Buildings... Ack.

radiance-general
1

Hello all,

  I'm having a problem with my buildings I'm exporting out of Revit, and am trying to figure out where the problem is coming from. I'm hoping someone out there can help me out a little with this issue, for I don't understand enough about Radiance to really know why this is happening, and can only guess at why.

  Just for the record, if I make a model from scratch using textfiles I don't have any of these problems. Additionally, the problem crops up whether I'm using Radiance on Cygwin, OS X, or Mandrake Linux, so it's obviously something I'm doing or a problem with the models coming out of Revit.

  My problem is the fact that my buildings all appear as if they are 'glowing'. Things like the site, and any Radiance-created objects or instances render correctly, however the buildings, especial the large flat surfaces such as walls and such, almost appear to be glowing because they seem to be bouncing so much light off of them, almost as if they are made of perfect white gypsum in broad daylight.

  The material definitions for the walls aren't set too high, the colors are typically .8 or .7 for the RGB values, and the roughness is usually set to .15 or so- both values that don't seem too far off. Also the Exposure for the scene tends to be about right for other Exterior Radiance scenes and the sun is a simple Gensky straight from the first tutorial file. Yet however the building will be bouncing almost twice the light off of it of anything else in the scene!

  The way I get my models from Revit to Radiance might be the key to why the models are behaving the way they are. I export the models to a DWG file that I then bring into AutoCAD and then use RADOUT to produce the models. However there are issues with this, for RADOUT or TORAD don't work quite right in the latest version of AutoCAD that I'm using. I've tried to use dxf2rad, but it always seems to choke on the models. They are very large, very complex, and have many surfaces. So I'm wondering if that's the root of my problem; is something in the export process possibly causing this?

Thanks for your time,

Jeffrey McGrew

2

Do you have a website where you can post an image? Maybe the normals are
flipped?
I've been having perhaps a similar problem - I do most of my modeling in
Infini-D Mac
I've modeled a buffet and there is a strange glow behind it -where it should
more of a shadow
http://rastermon.com/Rad/Dining.htm
In the QTVR, look at the buffet (where the candelabra and bowl are). I
never could find out why it had that light area where it meets the wall.
Also - the spaces between the drawers seem to glow.

Rob F

···

-----Original Message-----
From: radiance-general-bounces@radiance-online.org
To: Radiance general discussion
Sent: 5/27/2004 9:54 AM
Subject: [Radiance-general] Strange Glowing Buildings... Ack.

Hello all,

  I'm having a problem with my buildings I'm exporting out of
Revit,
and am trying to figure out where the problem is coming from. I'm
hoping someone out there can help me out a little with this issue, for
I don't understand enough about Radiance to really know why this is
happening, and can only guess at why.

  Just for the record, if I make a model from scratch using
textfiles I
don't have any of these problems. Additionally, the problem crops up
whether I'm using Radiance on Cygwin, OS X, or Mandrake Linux, so it's
obviously something I'm doing or a problem with the models coming out
of Revit.

  My problem is the fact that my buildings all appear as if they
are
'glowing'. Things like the site, and any Radiance-created objects or
instances render correctly, however the buildings, especial the large
flat surfaces such as walls and such, almost appear to be glowing
because they seem to be bouncing so much light off of them, almost as
if they are made of perfect white gypsum in broad daylight.

  The material definitions for the walls aren't set too high, the
colors are typically .8 or .7 for the RGB values, and the roughness is
usually set to .15 or so- both values that don't seem too far off.
Also the Exposure for the scene tends to be about right for other
Exterior Radiance scenes and the sun is a simple Gensky straight from
the first tutorial file. Yet however the building will be bouncing
almost twice the light off of it of anything else in the scene!

  The way I get my models from Revit to Radiance might be the key
to
why the models are behaving the way they are. I export the models to a
DWG file that I then bring into AutoCAD and then use RADOUT to produce
the models. However there are issues with this, for RADOUT or TORAD
don't work quite right in the latest version of AutoCAD that I'm
using. I've tried to use dxf2rad, but it always seems to choke on the
models. They are very large, very complex, and have many surfaces. So
I'm wondering if that's the root of my problem; is something in the
export process possibly causing this?

Thanks for your time,

Jeffrey McGrew

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3

Hi Jeffrey,

It sounds to me like you may have your ambient value (-av) set too high, or else you have ambient weighting switched on inappropriately. Try alternately setting -aw 0 and -av 0 0 0.

-Greg

From: "Fitzsimmons, Rob" <Rob.Fitzsimmons@Summit.Fiserv.com>
Date: May 27, 2004 10:52:15 AM PDT

Do you have a website where you can post an image? Maybe the normals are flipped?
I've been having perhaps a similar problem - I do most of my modeling in Infini-D Mac
I've modeled a buffet and there is a strange glow behind it -where it should more of a shadow
http://rastermon.com/Rad/Dining.htm
In the QTVR, look at the buffet (where the candelabra and bowl are). I never could find out why it had that light area where it meets the wall. Also - the spaces between the drawers seem to glow.

Rob F

···

-----Original Message-----

Hello all,

    I&#39;m having a problem with my buildings I&#39;m exporting out of

Revit,
and am trying to figure out where the problem is coming from. I'm
hoping someone out there can help me out a little with this issue, for
I don't understand enough about Radiance to really know why this is
happening, and can only guess at why.

    Just for the record, if I make a model from scratch using

textfiles I
don't have any of these problems. Additionally, the problem crops up
whether I'm using Radiance on Cygwin, OS X, or Mandrake Linux, so it's
obviously something I'm doing or a problem with the models coming out
of Revit.

    My problem is the fact that my buildings all appear as if they

are
'glowing'. Things like the site, and any Radiance-created objects or
instances render correctly, however the buildings, especial the large
flat surfaces such as walls and such, almost appear to be glowing
because they seem to be bouncing so much light off of them, almost as
if they are made of perfect white gypsum in broad daylight.

    The material definitions for the walls aren&#39;t set too high, the

colors are typically .8 or .7 for the RGB values, and the roughness is
usually set to .15 or so- both values that don't seem too far off.
Also the Exposure for the scene tends to be about right for other
Exterior Radiance scenes and the sun is a simple Gensky straight from
the first tutorial file. Yet however the building will be bouncing
almost twice the light off of it of anything else in the scene!

    The way I get my models from Revit to Radiance might be the key

to
why the models are behaving the way they are. I export the models to a
DWG file that I then bring into AutoCAD and then use RADOUT to produce
the models. However there are issues with this, for RADOUT or TORAD
don't work quite right in the latest version of AutoCAD that I'm
using. I've tried to use dxf2rad, but it always seems to choke on the
models. They are very large, very complex, and have many surfaces. So
I'm wondering if that's the root of my problem; is something in the
export process possibly causing this?

Thanks for your time,

Jeffrey McGrew

4

Jeffrey McGrew wrote:

  Just for the record, if I make a model from scratch using textfiles I
don't have any of these problems. Additionally, the problem crops up
whether I'm using Radiance on Cygwin, OS X, or Mandrake Linux, so it's
obviously something I'm doing or a problem with the models coming out
of Revit.

It might still have something to do with the different
complexity of the two models. Maybe a simple hand crafted scene
will just not show the effects you're observing, because there
is not enough context there to notice the difference.

  My problem is the fact that my buildings all appear as if they are
'glowing'. Things like the site, and any Radiance-created objects or
instances render correctly, however the buildings, especial the large
flat surfaces such as walls and such, almost appear to be glowing
because they seem to be bouncing so much light off of them, almost as
if they are made of perfect white gypsum in broad daylight.

  The material definitions for the walls aren't set too high, the
colors are typically .8 or .7 for the RGB values,

Most likely, this is *way* to high.

A freshly painted white interior wall typically has 0.7 0.7 0.7.
There are very few materials in existence with 0.8 0.8 0.8.
An exterior white wall will hardly ever have more than 0.5 0.5 0.5.

Remember that our eye has a logarithmic response curve. What
you perceive as "half as bright" actually has about 10% of the
luminance compared to the "twice as bright" reference. Doubling
the luminance of a surface will make the difference just about
visually noticeable, and only if both luminances are seen next to
each other. If I remember correctly, the standard "medium grey"
reference card used by photographers for calibrating their camera
measurements has a reflectance of 18 %.

Yet however the building will be bouncing
almost twice the light off of it of anything else in the scene!

That shouldn't surprise you anymore now...

  The way I get my models from Revit to Radiance might be the key to
why the models are behaving the way they are. I export the models to a
DWG file that I then bring into AutoCAD and then use RADOUT to produce
the models.

Radout knows nothing about materials, so this is irrelevant.

However there are issues with this, for RADOUT or TORAD
don't work quite right in the latest version of AutoCAD that I'm
using. I've tried to use dxf2rad, but it always seems to choke on the
models. They are very large, very complex, and have many surfaces. So
I'm wondering if that's the root of my problem;

No, that's an entirely independent set of problems (which I'm
working to solve anyway, of course).

-schorsch

···

--
Georg Mischler -- simulations developer -- schorsch at schorsch com
+schorsch.com+ -- lighting design tools -- http://www.schorsch.com/