[Radiance-general] Radiance, objline, objpict etc..

[Thomas Bleicher]

On 27 Jan 2008, at 14:42, steve michel wrote:

> Hi Thomas,
>
> MARK THIS SOLVED

Good. But see below ...

> I had created a 'glow' material and applying it to the same polygon  
> in my ies.rad file. SO I got a render with my fixtures showing but  
> still no illumination! I was trying to overlap or layer a glow  
> material on a distribution's polygon. So you are right that the two  
> might interfere. (But I can see where that might be useful to  
> avoid  the extra step of two distinct polygon geometry for the same  
> thing (which I have done before with erco fixtures 3d geometry))
>
> BUT The simpler method of deleting the -i option in ies2rad  
> worked...I see the fixture and the light distribution...

I'm still confused about your way of using ies2rad. You'd only
want to use the '-i' option if you want to replace the crude IES
geometry with a geometry file you created before and you don't
want the geometry to interfere with the distribution. A recessed
fitting has no visible geometry except for a bright disc or rectangle
and that's already covered in the IES file.

> The next challenge is to use a single light distribution material
> and apply to multiple similar geometry in the scene...

If you want to use the same IES file a few times just use the
*.rad file that's created by ies2rad a few times in your scene.

Example:

First create the description for the light fitting:

## this is typed at the command line
$ ies2rad -m 0.8 -t default aero.ies

This will create 'aero.dat' and 'aero.rad'. 'aero.dat' is
a converted description of the light distribution. This file
never changes. The 'aero.dat' file contains the material
definition and the geometry of the luminous area. This geometry
is necessary to create light in your scene. Whenever you call
ies2rad with different options but with the same IES file as
argument it will create the same .dat file but the material
definition in the .rad file will change (brighter or darker,
more or less white).

Then position the aero.rad file in your scene as required:

## these lines are part of the scene description
!xform -t 0 0 2.4 aero.rad
!xform -t 0 2 2.4 aero.rad
!xform -t 0 4 2.4 aero.rad


This will place three fittings at 2.4m height spaces at 2m along
the y-axis. You can create simple arrays with xform in one line
but that's not as illustrative right now. All of these fittings
will have the same output and distribution.

If you want to change the maintenance factor (-m in ies2rad) or
the lamptype (-t) you have to create a second file and use that
instead of the first 'aero.rad'.

Another more advanced way is to use ies2rad as an inline command
in the scene file and use a 'pipe' to transform the geometry:

## these lines combine the two separate steps above
!ies2rad -s -m 0.80 -t default aero.ies | xform -t 0 0 2.4
!ies2rad -s -m 0.80 -t default aero.ies | xform -t 0 2 2.4
!ies2rad -s -m 0.80 -t default aero.ies | xform -t 0 4 2.4


Note the additional '-s' in the ies2rad command.

When you run these lines through oconv the 'aero.ies' file has
to be present in the directory or you will get an error. After
the conversion, there will be one 'aero.dat' file while all
the material definitions and light polygons have been passed
through xform instead of being written to a .rad file.

This method has the advantage that you don't have to create
a new 'aero.rad' file for every dimming value you want to
try. Just modify the '-m' argument:

## same fitting, different dimming values:
!ies2rad -s -m 0.80 -t default aero.ies | xform -t 0 0 2.4
!ies2rad -s -m 0.60 -t default aero.ies | xform -t 0 2 2.4
!ies2rad -s -m 0.40 -t default aero.ies | xform -t 0 4 2.4


I hope this helps to solve your problems.

Thomas