Vectors for Casper

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cuteswan

Vectors for Casper

Postby cuteswan » Mon Oct 10, 2005 3:10 pm

Actually, it's probably not bad to give an explanation (though others probably have better explanations and examples).  Attention mods: I was about to put this into "The Creative Pen," but it's not really a tutorial; move or delete as you feel appropriate.  (Sorry, Casper, but this will probably lead to better explanations.)

Basically, vectoring is outlining an image with common shapes that can be described mathematically, such as with circles, ovals, rectangles, strange creatures called Bezier curves, etc.  If I tell you to "draw a two-inch circle in the middle of the paper" you can figure out the best way (using compass, perhaps), but if I say (like a bitmap would), "move three inches down, five point two across, put a dot, move .01 right, put another dot, a bit thicker..." then the circle will not be very smooth or consistent.  Also, in the first example, if you decide that you want to double, triple, half, 1/17th, etc. the image size, you just do the math for each "calculation," but with the dot method you'll get a lot of smudges when you try to press the dots so tightly together (or gaps when they're far apart).  (Just remember that I'm oversimplifying, as most printers and programs have ways to make a bitmapped image look good... but only up to a point.)

The advantage is that, since it's all calculated on the fly when drawn or printed, the quality is optimized for the size and media it ends up on, whether it's your inkjet, micro printing on Lincoln's nose on a penny, or a billboard.

Note that most fonts these days are stored as "vector objects" so that they can be scaled to any size, where a bitmap (picture) of each letter would lead to "blockiness" when made smaller and jagged edges when enlarged.  PostScript is (ideally) vector-based so that you will always get the smoothest image regardless of a printer or screen's resolution.

Most drawing programs have vector tools, and I've been using them since the early '90s (when I drew a wine glass as bitmaps and, when they came out jagged, re-drew them with vectors to make customer invitations for a wine tasting party ... Darn!  I used to be so creative -- what the heck happened?).

Here's a more recent example (from early 2004), a bit shrunk down, running left to right:

1.  This is the scanned drawing of "Soccer Girl," a.k.a. Susan.  That won't work well on the billboard for my netcomic.

2. I zoomed in on various parts of the drawing and overlaid vector objects.  In this example, I've zoomed into one point along the "freeform" object that defines her leg.  The line between any two points is described by a Bezier curve, and the two "handles" (topped with an arrow one end and circle on the other) adjust how the curve behaves.  (BTW, if anyone has a good description of Bezier curves, strategies for tracing with them, the history, Ms. or Mr. Bezier, etc., I'd love some links to it.)

3. I've dropped away the original drawing and have a pure vector object.  Note that the ickyness of the blown-up bitmap is gone.

4. I can adjust the line width and color (and even patterns, effects, etc.) for each object.  Also, I can scale the vectors to any size without any loss of quality (for all intents and purposes... I don't want to get too technical).

5. This is the finished project, with a quick and easy vector-based background (though the fill patterns are bitmapped, IIRC).  This can be blown up to a billboard (if I can just find one of those billboards on its side.  Maybe I'll print it on the head of a pin instead.)  In either case, I shouldn't rely on any art gigs in the near future.

6. This is the list of layers in the picture, Susan's body layer expanded to show the sub objects.  Note that (at least in Paint Shop Pro) an "object" can include multiple shapes, but the line width, colors, fill, etc. will be the same for all shapes in each object.  Example: Note that "skin" is one layer and "uniform white" is another though both have separate non-contiguous parts.)

Many artists actually turn the vector-based picture back into a bitmap before adding the final details and effects.  (And, in most cases, the pictures are posted/shared as bitmaps.)  At the very least, I hope this started to explain vectors without putting you to sleep. :)
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Re: Vectors for Casper

Postby Casper » Mon Oct 10, 2005 9:18 pm

Wow! You really go the distance! Thank you verrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrry much!

It seems much better quality after its done, but is it timely? All I would do for a coloring like that, is fineline, scan, and fill in with color. Any other effects like shading would take longer, but as long as the finelining is good, I dont have to touch any of the lines.

In saying that... I learned a fast way of 3-D coloring just 2 days ago. You just go over the part you want to color with a freehand select tool, and start coloring using diferent tones.

But anyway, all I really need now it, what program did you use?

I use 'Microsoft Picture it! Standerd 9'. Its very baisic, but functional. Does anyone else use it?
(I could give tutorials if you do)


And finaly. Thank you VERY much again. This will be a big help, and stop tose stupid jaged lines I always end up with. Cheers! :)
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Dagdamor

Re: Vectors for Casper

Postby Dagdamor » Tue Oct 11, 2005 5:37 am

Very interesting article! *promotes*
Probably it's for Creative Pencil. It didn't deserve to be dumped in the trashcan :)
cuteswan

Re: Vectors for Casper

Postby cuteswan » Tue Oct 11, 2005 5:50 am

Well, it's not really a tutorial, and I decided on my own that it was too obnoxious where I had put it, so this was about the only place where it wouldn't run up against any boards' guidelines.  If I had more horsepower in this computer, I could probably come up with a simple guide for outlining with Paint Shop Pro, though it appears (as someone who doesn't have PhotoShop) that PhotoShop has better handling of vector objects and Bezier curves.

Example: In PSP, you select a point on the curve, which can be defined as a corner on one side, curve on the other, etc., but you can only adjust the two sides of that point (so you actually get handles that control half of two adjacent segments and have to keep switching between two points to change a single segment).  However, in PS (IIRC) you are actually working on the line/curve segment between two points, which is much more natural.  Heck, I'd love to have two pointer devices and be able to manipulate both "definition points" simultaneously to get the curve right.

Argh, I'm ranting already. ;)  It's time for bed.
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Re: Vectors for Casper

Postby D.B. » Tue Oct 11, 2005 11:26 am

(BTW, if anyone has a good description of Bezier curves, strategies for tracing with them, the history, Ms. or Mr. Bezier, etc., I'd love some links to it.)
...
Example: In PSP, you select a point on the curve, which can be defined as a corner on one side, curve on the other, etc., but you can only adjust the two sides of that point (so you actually get handles that control half of two adjacent segments and have to keep switching between two points to change a single segment).
The reason you have to keep switching between handles is a single segment of a bezier curve (i.e. each portion which lies between two nodes) is a cubic equation defined by four points*. So when you're moving the handles you're literally moving one of the control points used to generate that segment (assuming the node is set to be a cusp. If it's asymmetric then you're also changing the orientation of one of the non-nodal control points in the adjacent segment of the curve with respect to the node, and if it's symmetric you're changing both orientation and relative distance). I don't know what method photoshop uses to alter beziers, but if you can actually tweak the curve directly then they must be doing some clever maths to calculate the necessary control point motion for you instead of making you do it by hand (or possibly they're using some other curve generating maths - catmull roll seems a little more open to direct curve manipulation to me, but that's just a guess). This doesn't look like a bad link for an explanation of the math of beziers -> http://www.moshplant.com/direct-or/bezier/

Anyway, yes, this seems valuable enough to stick in creative pencil to me, doubly so if it encourages other people to add their own contributions.

*Start and end points (refered to as nodes in psp), and a second and third point which when connected with a straight line to that start and end points (respectively) forms tangents to the curve at those points. The bezier curve also has the convex hull property, which means that the polygon defined by those four control points will always completely contain the segment of curve they generate.   
Last edited by D.B. on Tue Oct 11, 2005 11:28 am, edited 1 time in total.
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cuteswan

Re: Vectors for Casper

Postby cuteswan » Tue Oct 11, 2005 2:51 pm

Thanks for the move and the link, D.B.

Well, the Photoshop example I looked at shows the same behaviour: two control points are attached to each node (anchor point), each control point affecting a different side of the anchor, which means you have to switch between nodes constantly to work on the same curve.

I agree, though, that a direct curve tweak tool would be awesome (just grab the curve itself and move it).  The closest thing now is to go "freestyle" with the freeform tool, but that generates way too many anchor points and is tough to edit.

What I want is a way to edit the way it's shown in the Bezier link example, where the endpoints and control points for a curve are available at the same time.  In PSP and PS, you are forced to click on each anchor for a curve before you can tweak either of its control points.  (Sure, I've set up a bunch of keyboard shortcuts for all the functions, including prev. and next point selection, but PSP stores them in the order they were created, not the order along an object or shape, so if you add and/or delete points then you get moved to who-knows-where.)

Maybe a quick example will help.
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Re: Vectors for Casper

Postby Casper » Tue Oct 11, 2005 10:00 pm

Alright... I have 'Paint Shop Pro 5', 'Picture it! Standerd 9', 'Microsoft Paint', and a buch of other stuff that came with Microsoft Office.

I'm guesing your using 'Paint Shop Pro', but I cant find anything to do with vectors, beziers... and all the other stuff you said (??'??). I just want to get rid of the wobbly lines. It doesnt have to be the size of a billboard, or a pin head, just wobbleless... the rest I can do.

Thanks again!
Last edited by Casper on Tue Oct 11, 2005 10:03 pm, edited 1 time in total.
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Re: Vectors for Casper

Postby Archonix » Tue Oct 11, 2005 10:14 pm

That would be because Paintshop Pro didn't introduce vectors until PSP7, as far as I can remember. Maybe 6.
Our choicest plans have fallen through, our airiest castles tumbled over, because of lines we neatly drew and later neatly stumbled over.
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Re: Vectors for Casper

Postby Casper » Tue Oct 11, 2005 10:30 pm

Bah! Typical.

Well, I'm off to the shops. Thanks for the advice, and the tutorial! (And for putting my name on the topic tittle!) Bladmapples.
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Re: Vectors for Casper

Postby Marco » Thu Oct 13, 2005 10:03 am

I'm working on a little tutorial for whoever uses Photoshop (versions 6, 7, and 8 ) to do these vectored lines, i hope i can finish it before saturday...

The fact is that, i think, Photoshop uses a simplified version of the bezier curve. Its really easy to get the hang of how to make the curve behave as you want. more on this later :)

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