masking openings

radiance-general
1

I’m working on a python script which applies genetic algorithms for a façade
design (yeah, still doing that
)
I’m computing the fitness value of a given simulations by producing a
falsecolor image, by calculating the 64 brightest levels per channel, R
being most intense (direct light) , G being diffused light, and B for
shadows.

This approach seems to be ok, except that openings are also included, since
their bright values. I need to get rid of those. First I tried the most
simple approach, setting the viewfile such that the sky isn’t included, et
voila, openings are black. This approach seems oversimplistic, since it
yields a complete different rendering, looks like any source outside of the
clipping plane isn’t included (I suppose this is the expected behaviour). So
I need to do this in a smarter manner. Has anyone run into this before? The
best would be to render the mask as a separated image, such that they can be
combined using pcomb.

Cheers,

Jelle.

2

The best would be to render the mask as a separated image, such that they can be combined using pcomb.

Using a mask would seem sensible to me. There's a very small HOWTO on the radiance wiki that gives some basic info:

http://www.radiance-wiki.org/index.php?title=Mask_an_image

You'd probably want to generate your mask as a black and white image based on the polygon at that point. eg. if the polygon is 'sky', then output a 0, else output a 1.

Chris

3

Chris,

I'm familiar with the pcomb technique as found on the radiance-wiki, but am
lost in how to generate a 0/1 image where a 0 is outputted when a ray hits
sky. Would it be necessary to write a radiance functional language script
(.cal) for doing such?

4

Chris, changing the variable distance, you can create a mask with the
objects till that distance, i dont know if it's what you need

vwrays -x 200 -y 200 -vf myview -ff \

···

rtrace -oL -fff -x 200 -y 200 simple.oct\
pvalue -r -df -b|pcomb -e 'lo=if(gi(1)-distance,0,1)' - > image.pic

----- Original Message -----
From: "Jelle Feringa // EZCT / Paris" <[email protected]>
To: <[email protected]>
Sent: Wednesday, February 09, 2005 3:57 PM
Subject: [Radiance-general] masking openings

Chris,

I'm familiar with the pcomb technique as found on the radiance-wiki, but

am

lost in how to generate a 0/1 image where a 0 is outputted when a ray hits
sky. Would it be necessary to write a radiance functional language script
(.cal) for doing such?

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