how to cast shadows for a Piranesi epix render?

[Anonymous]

What's the best AC engine and technique for exporting shadows from the AC model into epix for a Piranesi render?

Ideally I'd use a Sketchup render, showing outlines and plain shadows only... but sadly that still isn't possible from AC, right?

The AC Sketch engine has it's shadow hatch line problem, and the other engines won't do plain shadows without including all the other rendered colors...

(Piranesi has a cool technique of using the shadows in its restore channel with a texture/grain and an RGB theshold allowing for nice colored shadows to be burned onto the render. But only Sketchup seems to provide the proper EPX template to do this from.)

Any ideas? Exporting the model to SketchUp and then from there to EPX is a lengthy workaround. Besides, the free SU version doesn't include exporting to .epx.

[Karl Ottenstein]

Whatever rendering engine you use will be the RGB channel in your Piranesi epix file. Your painting technique there determines if the kind of shadow produced will be useful or not.

You can of course change all of your materials in AC to white via Attribute Manager. Then, you can generate either hard or soft shadows without any textures interfering with your output.

But maybe you'd be happier to just import your model into Vedute (part of the piranesi package), which can give you the hard shadows you are after?

Karl

[Anonymous]

I'm glad to see your reply Karl as you seem to be the cross platform guru between AC and Piranesi from reading your helpful posts on the Piranesi forum.

I'll be trying your two suggestions next week. Regarding switching all Materials to white, however -- if I don't want to live with a white model in Open GL then I'd need to spin off a dedicated .PLN just for the render, which wouldn't stay current to evolutions in the original model, so that's a problem.

I just opened up Vedute for the first time (navigation looks clumsy, but shadows look great), and I see it won't import a PLN. Any advise choosing between a 3DS or SKP format when exporting from AC? I'd also like to get the identical perspective of a chosen render as back in the AC model, so I wonder if there's a mathematical XYZ coordinate solution for that.

Also, your reply seems to suggest you use other techniques to re-capture shadows from a blanked-out RGB channel in Piranesi, other than the technique I describe above. Could you elaborate? (sorry that's off-topic from AC) In other words, what order of operations do you like best when moving from an AC model to a Piranesi render?

THanks,

[Karl Ottenstein]

Hi Michael,

No, you don't have to get rid of your OpenGL materials permanently. Follow this post:
http://archicad-talk.graphisoft.com/viewtopic.php?p=117641#117641

to save your existing materials with Attribute Manager, and then define a new set of materials that are all identical, perhaps foam board. Save that too as an AAT file. Then you can switch back and forth inside AC between the two AAT files to get the different appearances.

I think that will provide you with what you want - and then either Internal engine for hard shadows, or LightWorks for soft.

I'm still working on being artistic with Piranesi, and so have primarily used it for photo-realistic work. For that, I prefer to take the ArchiCAD model into Artlantis and from there into Piranesi.

I've never attempted to get Vedute to match an ArchiCAD view. I suspect it would be pretty impossible to get it pixel-perfect. (The advantage of having pixel-perfect views - that is, not a single pixel off in the alignment of a like-sized image - is that Piranesi lets you import a new RGB channel, so you can have multiple types of renders from the same view, work in Piranesi and 'render' there (save RGB as the restore-RGB) and then bring in a fresh RGB image to work with restore brushes, etc. For example, bring in an ArchiCAD Sketch render and restore some color.

SKP export wasn't around the last time I went into Vedute, so I'd say to just try 3ds (what I used to use) and skp and see what works best for you.

By the way, Piranesi lets you paint QuickTime VR scenes - but you cannot export a VR epix file from ArchiCAD. Instead, you export the model to Vedute and set up the VR there. Just to give another reason for why Vedute is around.

Cheers,
Karl

[vfrontiers]

Karl,

I like your "Swappable" ATT file trick. What I've done in the past (not intended for Piranesi) to achieve a stark white model from which to collect only shadow data was the to SAVE the 3d as an OBJECT, then after placing the object in a plan, OVERRIDE all materials with one.

Yes, I know, if the model changes you have to do it all over again...

[Anonymous]

Yup Karl, you're the best -- that ATT swappable trick works for me too. The "white foam board" model will go into Piranesi quite nicely.

I've become a major fan of Piranesi and non-photorealistic renders over the photorealistic stuff, but that's another discussion. (And I get to abandon fiddling with LightWorks entirely!)

[Anonymous]

Yes, I find attribute swapping so useful that I'd like to see it built in more conveniently. With libraries of attributes that can easily be shared between projects. But the manual method is still pretty good for now. (BTW: I haven't figured out anyway to do this in Revit yet.)