[Radiance-general] Five-phase Method Tutorial: all-black models in the Daylight Matrix and the Direct Sun Coefficient Matrix

[Alireza Hashemloo]

Hello,

I have two set of questions regarding the Direct Daylight Matrix and Direct
Sun Coefficient Matrix calculations in the Five-phase method tutorial  (
http://www.radiance-online.org/learning/tutorials/fivephasetutorialfiles/Tutorial-FivePhaseMethod_v2.pdf)
that I would appreciate if you could help me with:

OS: Windows 7 (64-bit)
Radinace: 5.0.a.8
Command Line Environment: Git Bash


1- Direct Daylight Matrix and the all-black model:

the all-black model for Direct Daylight Matrix is generated by the
following command:


Command:

$ xform -m black objects/testroom_Swall.rad objects/testroom.rad
objects/ground.rad \
objects/venetianblind.rad | oconv materials/testroom.mat -
objects/viewmtxsurf.rad \
objects/daymtxsurf.rad skies/sky_white.rad > octs/model_allblack.oct


Description:

The "viewmtxsurf.rad" file which contains the definition for the view
polygons (window glazing pane at the interior side) assigned with a glow
modifier, is exempted from the 'xform' call and it is passed to the 'oconv'
with a hyphen: "- objects/viewmtxsurf.rad"


Questions:

- If Radiance is only going to sample random points within the geometric
outline of the daylight polygons (window glazing pane at the exterior side)
to find the sky patch contributions to the Klems' patches, why are the
"viewmtxsurf.rad" and the "venetianblind.rad" (which are both at the
interior side) even passed to the 'oconv' to be part of the
'model_allblack.oct' file?

- What does the hyphen "-" before 'objcets/viewmtxsurf.rad' do in this
procedure? (I have checked the 'oconv' command  description but I could not
understand the given explanation for the hyphen)




2- Direct Sun Coefficient Matrix: Illuminance Calculations Vs. Rendering

In the tutorial, the Example 1 describes the application of five-phase
method for illuminance calculations and the Example 2 describes the method
for renderings (luminance maps). There are obviously, overlaps between the
two examples. With regards to the development of the Direct Sun Coefficient
Matrix for illuminance calculations (Example 1), a 'model_suns.oct' file is
generated as follows:


Command (generating the 'model_suns.oct' file):

$ xform -m black objects/testroom_Swall.rad objects/testroom.rad
objects/ground.rad \
| oconv materials/testroom.mat - objects/glazing.rad
objects/venetianblind.rad \
objects/glazing_bsdf.rad skies/suns.rad > octs/model_suns.oct


On the other hand, the Example 2 for renderings uses two separate octree
files to generate the Direct Sun Coefficient Matrix: 'model_suns.oct' and
'model_nosuns.oct'


Command (generating the 'model_nosuns.oct' file):

$ xform -m black objects/testroom_Swall.rad objects/testroom.rad
objects/ground.rad | \
oconv materials/testroom.mat - objects/venetianblind.rad >
octs/model_nosuns.oct


Questions:

- Why is the 'venetianblind.rad' passed to the 'oconv' call in the command
generating 'model_suns.oct' without a hyphen "-", whereas the
'venetianblind.rad' is passed to the 'oconv' call in the command for
generating 'model_nosuns.oct' with a hyphen?
- Why is the 'glazing.rad' (which is an identical polygon definition to
'daymtxsurf.rad' with a glass modifier) is included in the 'model_suns.oct'
file but it is excluded from the 'model_nosuns.oct' file?
- Unlike the 'model_allblack.oct' for Direct Daylight Matrix, why is the
'venetianblind.rad' not assigned a 'black' modifier in the Direct Sun
Coefficient Matrix calculations ?


Thank you in advance for your assistance,

Alireza
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