Hi, i need help to set a metal mesh (solar protection for a big facade of glass). i don´t know how to create a new material like that, if maybe should i create a "glass" or another material to pretend to be that for the simulation. To be clear, i add an example how the building looks like:

http://4.bp.blogspot.com/-wCThXwC6jiw/T_V5By-lngI/AAAAAAAADXc/dp7Eb...

Any recomendation will be welcome.

Thanks you.

Tags: Solar, protection

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Hi Camila,

 

You have some pretty perfect timing with this post. I just produced a document for some of my students that might be helpful to you. By the way, to make simulating these worthwhile, you will need to increase your ambient divisions (ad) values substantially.

 

To learn about putting these material definitions into your materials library, see this link.

 

Best,

Alstan

 

Automated Punched Hole Generation in a Planar Surface

There are many procedural material options in Radiance; however, one that might be particularly useful for students is the idea of a perforated screen. We can define two materials -- a very transmissive glass and a plastic -- and combine them in such a way to produce a screen material. For this to work, you must download a special calculation (.cal) file and save it in the C:\DIVA\Radiance\lib\ directory.

 

The below glass and plastic materials are referenced by the perforation material examples below.

void glass open

0

0

3 1.0 1.0 1.0

void plastic plastic_bluegreen

0

0

5 0.000 0.723 0.666 0 0

To control the appearance of the openings, there are two important values. The –s value deals with surface subdivisions relative to UV coordinates. A value of 1 will leave you with comically large holes, while a value of .05 will give 1/0.05 = 20 holes per U-V unit. The parameter at the end (0.4 in the first example below) sets the relative radius of the holes. A value of 0.5 will have the hole edges barely touching. A value of 0.25 will use half of that radius.

 

Examples

void mixfunc perforated_s5_r4
6 plastic_bluegreen open uv_hole perforate.cal -s .5
0
1 0.4

 

 

void mixfunc perforated_s1_r4
6 plastic_bluegreen open uv_hole perforate.cal -s .1
0
1 0.4

 

 

void mixfunc perforated_s05_r4
6 plastic_bluegreen open uv_hole perforate.cal -s .05
0
1 0.4

 

 

void mixfunc perforated_s05_r25
6 plastic_bluegreen open uv_hole perforate.cal -s .05
0
1 0.25

Thank you very much, I really appreciate your prompt response, I'm working on it. 

Soon i`ll let you know if i have any contribution about it.

Camila Herrera

Hi.

Thank you so much for posting this document.

I am just having a bit of trouble getting the simulations to work. They are failing with the following error: Could not find C:\DIVA\Temp\screentest\screentest.amb " [attach screenshot].

Perhaps I am not following our instructions correctly. I copied the calculation file into a notepad and saved it as perforated.cal in the radiance /lib directory. Then copied the glass, plastic material and perforated functions and pasted them on my material.rad file. 

I can't seem to figure out what went wrong. Any leads would be very helpful. Thank you.

Ale.

Attachments:

Hi Ale,

The error causing the issue is actually happening further up in your output. Could you screenshot the upper part as well?

Best,

Alstan

Hello,

I just tried to use one of these materials but DIVA doesn´t recognize the mixfunc-materials. Actually, "open" and "plastic_bluegreen" is recognized in the material panel in grasshopper but it´s not accessible within the material dialog in Rhino. Kind of strange..

- Sophie

Hi Sophie,

Apologies for the late reply.

In the toolbar's Material menu you should see all three materials: the plastic, the void and the mixfunc. It may indeed be that the DIVA-Grasshopper component does not identify the mixfunc material.

Best,

Alstan

Hi Alstan,

Thank you for your reply.. the material "appeared" after some time..

another question.. how can i "reconstruct" the appearance of a perforated panel I would like to test with this DIVA.material? I mean I would like to test several differently perforated panels to see which one performes best. How can I resemble their appearance through this material?

while a value of .05 will give 1/0.05 = 20 holes per U-V unit

I don´t really see where the UV-values are defined.

Thank you!

- Sophie

Hi Sophie,

In my experience, getting the appearance just right is a process of trial and error. I think there is probably some logic to it, but usually I just tweak the values using low-quality renderings as my guide until I get the proper result.

Alstan

Hi Alstan,

Sorry to bring up an old thread, but I was looking to model a metal mesh and found this discussion thread through Google. I'm trying to use the steps that you recommend, but for some reason I cannot get the mixfunc material to show up in the Diva materials selector. The open and plastic_bluegreen materials show up, but the mixfunc does not. What am I missing? (I placed the perforate.calc file in the radiance/lib folder)

Thanks for any help

-Vikram 

Hello Vikram,

Are you using DIVA for Grasshopper to do this or the toolbar?

Best,

Alstan

Hi Alstan,

I'm using the grasshopper version. Does that not work? 

Hello Vikram,

I believe that Grasshopper does not identify the mixfunc material unfortunately. I've forwarded the post to the DIVA-GH guys to confirm.

Best,

Alstan

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