Transparent material casts shadow

[Anonymous]

hello everyone,
this is an old issue .
I need to study sunlight and shadows for a complete plan which comes through windoes ..etc.. so, I select top view and render with hide ceiling , subsequentely the sun light enter the room from the space of hidden ceiling ( in the attachment I need light in blue boundary but without that ones in yellow )
what I ask for is, can I found a way to give the ceiling material which I can see through but cast shadows ,
I hope I can found the answer with cinerender but if any way with render or without are welcome
and I don't know If I can get that from Rhino and grasshopper
thanks in advance
................................................................................................

about ten years ago I asked the same question and I get this great answer (and have kept it for long time and I had used it with LW render before it was removed by cinerender )


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If I understand you correctly, the question you are asking is "How can I
do a sun study of the floor plan, but with the roof still in position so
you can see the shadows cast from it?"

Palawat gives a possible solution here
<http://archicad-talk.graphisoft.com/viewtopic.php?t=19618>.

To paraphrase - Set up a new lightworks material with the material's
Colour Class set to Plain > pure black and set the Transparency Class to
Plain > pure black also. Temporarily apply this material to the roof and
any other structures you need to see through but still want to cast
shadows.

Apparently there are some issues with multiple light sources, but give
it a go anyway!

What's really needed is a true 'shadowcaster' material/shader. One
that's completely transparent, yet still casts a solid shadow.

I wonder if Artlantis has this function? Dwight?

Hope that helps!
_

[Erwin Edel · Accepted solution]

That video deals with similar setup for a wall you can see through. If you turn on subtitles and translate from Russian, you should get the general idea.

[Christophe Fortineau]

Hello Alammouri,

"...to study sunlight and shadows...

First of all did you georeference correctly your model into "Option/Environment Project/Project location" ?

"...I don't know If I can get that from Rhino and grasshopper...

It is possible with these tools but it is also often possible to do without.
You can do two views with each shadows you want
You are able to disable transparency (about your windows) into on of your doc 3D view to delete your "blue" shadows inside you construction. Finaly put these views on a same layout.

[Anonymous]

Erwin wrote:


That video deals with similar setup for a wall you can see through. If you turn on subtitles and translate from Russian, you should get the general idea.

thank you, that exactly what I was searching for ,
I just faced one problem with language not in the youtube but in the AC menus so I try to count the order in menu and that does not work because the orders sort alphapictally. I get the idea and it works prefectly thank you again

[alemanda]

I'm in AC24 and it doesn't work with the wall while it works with a sphere like in the video tutorial.
Where do I make the mistake?

EDIT. I found where I was wrong. It works! Great method! MANY THANKS!

[jkershaw]

I tried this method today in order to create a top-down (plan) view with shadows created by a transparent roof. It did not work in Archicad 25.

Notably:

1. When using the Redshift rendering engine, the Alpha settings of the Surface seem to be ignored. I could only follow the video tutorial using the Standard Cinerender engine.

2. I was unable to create a transparent material that casts shadows in either Cinerender engine. I readily admit, this could be an error on my end, but I tried everything I know.

3. Even if I was able get a transparent material that casts shadows, the fact that it does not work with Redshift makes it useless. We are working with a large complex model and waiting for the Standard engine to render is not an option.

In conclusion... we STILL need a way to visualize accurate shadows (with the roof on) in a top-down view.