Hi all,

I have a quesion about watercolor effect:

I know there is NPR (Non-Photorealistc Rendering), which can create some pretty impressive sketch and watercolor effects. It does take quite a lot of experimenting to get right and quite a lot of patience to render. Since NPR has not been updated for multi-core rendering, it does take painfully long to render and even before that - to compute the strokes. Added to the trial-and-error tedium of setting it up, it does become a bit of a pain and time-sink.

(Unless I am doing it wrong and there should be much less of a trial-and-error process for the setup! If so, please tell me, because I'd love to get better at it!)

So, I am here looking for alternatives. My thinking is that there might be a combination of lighting rig + shaders, which might yeld and interesting watercolor result. At this stage it'a hunch as I don't quite know how to go about setting it up.

Hence, the questions:

a) Have you ever stumbled upon a lighting rig/accident, which made the render look "painted" or strangely blotchy as opposed to realistic?

b) Poser shader trees have some elements called "color clipping" and other procedural setting, which appear to allow for watercolor-like and other media-immulating shaders (there is a pack of them sold at RDNA, although I don't have a Poser version in which I could actually test them to see how they work). Is there anything that could wotk similarly in Carrara.

c) Carrara has alternative Lighting Models, and even more Lighting Models come with Shaders Plus from DCG. Could any of these models be used to help creat a more painted/traditional media effects?

d) Any other suggestions would also be very welcome!

Now for the other odd questions:

1. If I want to set up a scene in Carrara, and then create some form of render (HDRI?) to be able to use that render as a backgtound/spherical-map-environemt for other scenes (to save render time), how you I need to set up my camera and lights/render settings?

2. If I have a vector, I'd like to be able to import as a path into the vertex modeler, how would I go about it and is it at all possible? Are there special formats/vector properties that need to be observed for a vector to be usable in this way? And where in Carrara would I fing the import/loading options for it?

Thank you! And sorry for the questions being all over the place.

Primary question:

NPR is very slow, beautiful but slow. A) I would be inclined to build some watercolor shaders and then experiment with color clipping, or B) Another way might be to use a uniform white shader on everthing but create watercolor gels and project onto the objects. Since you can deselect object from being lit by any individual light, you could pretty easily control the effects placement. 

Other questions: 

1. Set up your scene and utilize a speherical camera for a scene render, placed at the center of the scene. As for HDRI application, check out this tutorial I made few years ago.

2. Vector paths do not import into the Vertex room. You can bring them into the Spline room, create a shape and then convert to polygons. 

Thank you, Mark!

From your answer I am guessing that there is no better method to NPR setup than trial and error?

A) How would I set up Color Clipping in Carrara? Or were you referring to post processing for the clipping? And when you say "build watercolor shaders" are you referring to some Carrara-assisted shader creation, or just shaders based on watercolor painted textures?

B) That sounds like a brilliant idea! I'll try to see how well it can be implemented.

Other things:

1. I love that Dark Arts Tutorial! I've followed it before when I needed some technical reflections. But here my question was more specific: what settings to use for things like camera position/orientation and render ratio to have a map what would, when imported look correctly scaled for an environment that matches the scene it originated from?

When I import HDRI images, they all work very well for reflections, but when used as backgrounds they often apprea pixelated/distorted/not really space/perspective accurate. So I was wondering what I need to do to prevent that?

1. Ah, thank you! This makes perfect sense.How would I go about preparing the ai files for such import (aside from saving as AIv8)? Do the paths in AI need to follow any rules in order to work for the import? I tried importing a compound path and some of it imported properly, while some parts resulted in a very messed up geometry, and I just don't see a reason why that would happen, because the messed up parts seem no different than the non-messed-up ones...

Another question I always stuggle with is whether there is a way to rotate a crosssection plane in the spline modeler? I think the answer is "no", but I keep wishing it would be "yes"...

Thank you again for your answers!

Clipping with one of DCG's plugins is what I meant since there is no native clipping abiity in Carrara. 

HDRI: the camera simply needs to be set as Spherical and at the 'eye' level you want the horizon line to be when used as a spherical background - for outdoor 0,0,0 is good, indoor will probably be the height of the camera if you were standing. The reason many free HDRI and spherical background look bad is because they are low res. Most need to be rendered between 4,000 and 5,000 pixels wide at a minimum. To look crisp on render 20,000 x 10,000 pixels is good (a 2:1 ratio is the target for outdoor environments) A little math, if your visible spherical background is 10 percent of 360 degrees at 72 ppi then the total background width should be 36x10x72 or 25,920 pixels wide. Interpolation of the back ground at render helps keep resolutions managble. I do have some static backdrops that are 10,000 pixels wide for slow pans across a 16:9 field of view. 

As for indoor renderings, the proportions will require more experimenting if you will be doing an animated camera move. The reason is that the background room and the modeled area will need to be in agreement with perspective/lens adjustments. A Macro close-up won't seem to agree with a 50mm lens for the room. DOF can be your friend on this one. 

Forgot the Vector line stuff. Compound paths and such import successfully as cross sections. They will not import as the wall projections. You can rotate the cross-section if you are using Pipline Extrusion. However, you can also simply select the cross section of your choice, select all points and use the rotation tool as well.

I typically save my .ai files as v3 for maximum compatibility. 

Now I know what the Clip in Shader Ops is for! I never had a chance to use it.

Thank you for the HDRI tips. The scenes I had in mind where indeed outdoor scenes, so it should simplify things a bit.

For the interior, though, I see that the spherical camera does have the lens zoom setting, but I don't see a difference in the renders when the setting is changes. Is it because the spherical camera ignores the setting, or do I need to check some other option for this to take effect?

Quote - Forgot the Vector line stuff. Compound paths and such import successfully as cross sections. They will not import as the wall projections. You can rotate the cross-section if you are using Pipline Extrusion. However, you can also simply select the cross section of your choice, select all points and use the rotation tool as well.

I typically save my .ai files as v3 for maximum compatibility. 

I was importing the path as a crossection. The image is attached. (Saving it as Av3 yelded the same distortion :(...)

For the wall projection(envelope/sweeping path), does the path need to be opened or closed? Does it need to be oriented in a special way?

Also I found that I can rotate the cross section on its plane, but I cannot rotate the plane itself in 3D (with either extrusion method). The rotation is in # of degrees CW or CCW, but within the same plane. Am I doing it wrong?

Thank you again!

HDRI: Spherical cameras are a one-trick-pony. No options change the function.

Imported ai files need to be open for the wall projections. (although circles work if pipeline is the extrusion method - which also means other shapes should work too - just not compound)

Rotating Cross-sections: If you use a spiral preset in the spline room, you'll discover that the cross-sections to rotate. But the rotation is a function of the bezier handles on the wall projects and not somethign that you can control directly. 

As for your imported art that is malformed, there are two areas to trouble-shoot: 

1. The easiest one is going into the Spline Room > Geometry > Surface Fidelity and then increasing that to someting like 400. This setting also effects how many polygons are generated during a conversion to a vertex model so if the model gets 'fixed' with a lower setting than 400, you may want to keep the lower setting if planning to convert. 

2. The source file might have co-located points but not welded points in the problem areas. For areas where there are problems, mover around the shape selecting each point by click dragging a marquee and then choose the 'Join' option. You'll get a notice if nothing is joined, if there is no notice, it means that double points got connected and 'sealed' the shape. 

Thank you again for all your answer, Mark!

For that particualr path no amount of Surface Fidelity seems to help. I was able to separate the working portions and import the others as separate figures, but then my Carrara is acting weird lately, and I can't quite figure it out. (I just posted another question about it.)

(Sorry for the delayed response, I got swamped by life and work and only now got back to testing things in Carrara.)