Sky View Factor calculation: different possible approaches.

The Ladybug_Shading Mask component allows to define the Sky View Factor starting from a 3D model.

The Rayman software or other sw allow to do the same starting from a real image captured with a fish-eye.

I have seen if in ladybug there is a specific component but I have not found it. So I ask: "have you considered to implement this features in ladybug?"

Regards,

Francesco

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Replies to This Discussion

Permalink Reply by Mostapha Sadeghipour Roudsari on December 6, 2016 at 7:18am

Francesco,

Are you looking for a component that takes a fisheye image as an input or a workflow to create the whole process in Grasshopper? Grasshopper's Image sampler does take an image and returns the colors for each pixel. You can use Honeybee to render a fish-eye view looking to the sky and then count the number of sky pixels. Apply a black material to all the geometries, generate a uniform sky and set -ab to 0 and pick a high value for -ar.

Mostapha

Permalink Reply by Mostapha Sadeghipour Roudsari on December 6, 2016 at 7:39am

Here is an example.

Permalink Reply by Francesco on December 14, 2016 at 4:00am

Dear Mostapha,

I have used a basic image (Image_for_comparison.bmp, attached below) to compare the SVF calculated with Rayman and that calculated using the above simple script (I have modified it by adding "1-" in the formula).

As you can see from the two images below, the result are a bit different and I'm not able to found an explanation.

Can you try to explain me why it happens?

Attachments:

Image_for_comparison.bmp, 678 KB

Permalink Reply by Francesco on December 14, 2016 at 4:28am

I have also used the image attached below but the difference in the two values determined by the two softwares persists. I think is due to the different geometry of the input image: square vs circular

How can I exclude the 4 corners in the native grasshopper image sampler component?

Attachments:

Image_for_comparison_r3.png, 34 KB

Permalink Reply by Francesco on December 14, 2016 at 6:57am

Update.

I have tried a new code:

Important: in input you have to consider a .png file with transparent background

Permalink Reply by Francesco on December 6, 2016 at 8:12am

Are you looking for a component that takes a fisheye image as an input

Exactly

Permalink Reply by Mostapha Sadeghipour Roudsari on December 6, 2016 at 8:56am

We don't currently have a component for that in Ladybug but as you can see in the example file you can use Grasshopper native components to get what you need.

Permalink Reply by Francesco on December 6, 2016 at 9:27am

I have seen.

Thank you Mostapha!

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