shadow catcher

[Anonymous]

isn't the shadow catcher material supposed to just receive shadows but not cast shadows? when I set it it both receives and casts shadows!

I'm trying to do a shadow study where I can see the shadows of my building but not the other shadows, then I must overlay it in photoshop over the other renderings of all the context buildings without our building, all this complixity is becasue they want to see the shadow of our building in a different colour from the shadows of other buildings.. any ideas!

Is there a way to get different objects to cast different colour shadows?

[Dwight]

The shadowcatcher is itself invisible, acting as a "hole" in 3d space to reveal the background photo - like a knockout would. It does cast shadows.

You might search the forum for my shadowcatcher article - part of my book given freely to our community.

I can't get colored shadows in LightWorks, either, even after experimenting with colored glass.

However, the photoshop overlay method isn't that tricky, is it?

[Anonymous]

thanks Dwight, yeh I ended up with a compromise solution, I used two models one with the background buildings in shadow catcher material with red shadow colour, and another with normal materials but without my building, then overlaid them in Photoshop. of course this being a shadow study I had to do this for 30 different times of the year and day! But Photoshop Automated Actions made the process easier and less repetitive, if anybody ever gets a request for something like this I'll be happy to give more details into the process, I doubt this is something a lot of clients would ask for.

[Anonymous]

Hassanen wrote:
I doubt this is something a lot of clients would ask for.

It's becoming more common as some jurisdictions are now requiring shadow studies as part of their environmental impact standards.

[Anonymous]

Matthew wrote:
It's becoming more common as some jurisdictions are now requiring shadow studies as part of their environmental impact standards.

yes, in all Toronto high rise projects I've been involved with so far, it's been a requirement (along with wind studies, which we sent out to an engineering firm that does it using a physical model in a wind tunnel), it usually means simply running ArchCAD’s “Create Sun Study” , however the client in this case has asked specifically to show the shadows of our proposed building in two different heights with two different colours that are different than the colour of the surrounding buildings’ shadows, which does complicate things a bit!

[Erika Epstein]

Hassanen wrote:
thanks Dwight, yeh I ended up with a compromise solution, I used two models one with the background buildings in shadow catcher material with red shadow colour, and another with normal materials but without my building, then overlaid them in Photoshop. of course this being a shadow study I had to do this for 30 different times of the year and day! But Photoshop Automated Actions made the process easier and less repetitive, if anybody ever gets a request for something like this I'll be happy to give more details into the process, I doubt this is something a lot of clients would ask for.

Please do write it up.
It would be very useful as well as it might also earn you a tip mug!

[Dwight]

This is a simple exercise to visualize once you know that any object made with a material using the Shadowcatcher shader can be told what color its shadow is.

See:shadocatcher red shado

[Anonymous]

a link to a previous thread
where red casts red a red shadow
it shows the material settings
http://archicad-talk.graphisoft.com/viewtopic.php?t=13410

[Anonymous]

I'm trying to do the same now with AC11, but it seem the shadow catcher objects are casting shadows.
the way I recall it in AC10 the shadow catcher objects, only RECEIVE shadows but they don't CAST shadows.