Tips for tracing raster images using Pen/Bezier tool: (This is a rough version. I think I'll make a tutorial out of it.)
1 - Select the image
2 - Object menu > Object Properties > Image Rendering > Optimize Speed (this makes the pixels visible which helps to make a very faithful tracing of the image - but is optional - if you don't like it, just switch back to "auto")
3 - Zoom into the image so far that you can see the pixels. Depending on several things, this might be around 700%, more or less
4 - Make a new layer (Layer menu > Add Layer)
5 - Look at the bottom of the window where you can see a small dropdown (well, it really drops up
. Choose Layer 1, and click the TINY lock icon (it will change from open lock to closed lock). This will keep you from accidentally moving the image, and getting your drawing messed up. By the time you realize it was moved - well, this is a big time-saver. But note that after you lock it, you can't select the image anymore, until you unlock it.
6 - Enable the Pen/Bezier tool
, and look at the control bar. Click this button
. It forces the Pen to draw in straight lines only. Because you're zoomed in so far to draw the path, when you zoom back out, you might not even notice that it's made of straight segments. But if you do notice, you can change them to smooth curves all at once. (Or almost all at once, but in any case, a WHOLE lot faster than making smooth nodes one at a time!)
The reason I do this, is because I can't control the mouse well enough to create smooth nodes, and still work with any reasonable speed. (To create a smooth node, instead of clicking once, you have to click and drag AND adjust the curve, before going on to the next node.) This technique does not require you to adjust each and every curve. You'll only need to adjust a few, or maybe none at all. And I can click through and set all the nodes really fast this way.
7 - Select the new layer, whatever you decided to call it. (If you don't select Layer 2, you'll think Inkscape is broken.) Select by opening the drop-up menu, and click on it. Move the mouse to where you want to start the path, and click once. After that, click once wherever you want to place a node.
8 - I find it best to place nodes at the apex of curves, which means the highest or lowest point of the curves. With very gentle curves, sometimes the nodes will be inches apart. But in tight curves, you might need to place them fairly close together. However, try to use as few nodes as possible, at least for the first time, until you have more experience.
9 - Click, click, click along the border of what you're drawing. Because you're zoomed in so far, you can see the border very easily, go really fast, and still be accurate. Also, you might only place one or 2 nodes before you need to scroll on ahead, especially in areas where the curve is long and gentle (or pan, if you prefer panning to scrolling). Instead of making one huge, long path, I prefer to make the path in shorter sections. If you need to undo a node,
don't click the undo button!! If you need to undo a node, press the Backspace key. Press it once for each node you want to undo.
10 - When you're ready to end a section, double-click. Notice when you double-click, the line turns from red to (usually) black. If it seems too wide, it's because you're zoomed in so far. You can make it narrower if you like, using Object menu > Fill and Stroke > Stroke Style tab > Width.
11 - Also notice that there's a tiny square at the end of the new path. Place your mouse over that square (you might notice it turns red, when the mouse is in the right place) and click once. This will automatically extend the path you've already started. If you don't put the mouse in that tiny square, you will be starting a brand new path, and you'll have to take an extra step later to connect it to the first one.
12 - When you get all the way back to where you started, click once in the tiny square.
13 - Zoom back out and look at your new path. (Press the 1 key to go automatically to 100% zoom.) At this point, if you made the path narrower earlier, you might need to make it wider again now, because it might be hard to see. Decide whether you want to leave it as it is, or whether you want to make the corners smoother.
14 - If you want to make the corners smoother, chances are you don't want to make every corner smooth. Almost always there will be places where you want a nice sharp corner, and other places that you want curved. Say for example, the old fashioned kind of ice cream cone, where the bottom of the cone is pointy. You want the ice cream part to be smooth, but you want the bottom point, and maybe where the cone meets the ice cream, sharp.
15 - Switch to the Node tool
. Now you'll actually see all the nodes you placed. Press the Ctrl key and the A key together, which selects all the nodes. Release those keys, and now press the Shift key. While the Shift key is pressed, click once on each node that you want to stay sharp. (The shift key keeps multiple nodes selected. If you don't hold the Shift key, all the nodes will be deselected.)
If there are too many nodes that you want to stay sharp, there are a few other node selection techniques you can use. If it's really just a handful of nodes that you want to be smooth curves, the hold Shift and click once on each of those nodes. Or you might want to drag a selection box around several adjacent nodes that you want to change to smooth. Hold the Shift key, move the mouse over to the next section of nodes that you want to be smooth, and drag another selection box around them. Don't let the Shift key up until you finish selecting them all.
When you have all the nodes selected that you want to be smooth, look at the Node tool control bar, and click this button
(Make selected nodes smooth).
16 - If you needed to zoom back in to help with node selecting, zoom back out to 100% and inspect your path. Likely there will be a few smooth nodes here and there that you need to adjust. Zoom into the node if you need to. (Yes, I zoom like crazy when I'm tracing a raster image - in, out, in, out, etc.) Ok, so you can click on the node to select it. When you do that, you'll see the node's handles, which are a very thin, blue line with a very tiny blue circle on the end. You can grab the circle with the mouse pointer, and drag it. As you can see, you can make the handles longer or shorter, and rotate them around. Notice what's happening to the path when you do that.
If you don't see handles on selected nodes, you might need to enable handles. On the Node tool control bar, click this button
. Remember that you can only see handles on nodes that are selected.
If you enabled the handles, and a node is selected, and you don't see handles, then it's a corner node. Corner nodes are diamond shaped, while smooth nodes are square. (There are round nodes too, but it's not for this tutorial to explain them.) If you have a corner node, clicking the Make Selected Nodes Smooth button sometimes doesn't bring out the handles (I think might be a bug, but never got around to investigating).
If that happens, you can drag the handles right out of the node. Place the mouse pointer over the node, hold the Shift key, press the mouse button and drag a short distance in any direction. You'll see the handle come right out with the mouse pointer. Release both mouse and Shift key, and adjust the curve.
If you want to make a smooth node into corner, you can retract one or both handles. Place the mouse pointer over the tiny circle at the end of the handle. Hold the Ctrl key, and click once. If a smooth node only has one handle, you cannot move the handle (not sure if that might be bug too). If you need to move the one handle, change the node to corner (control bar, button left of smooth node button).
There are several key combinations that can be used to move the node handles in different ways. Personally, I've never found much use for them, but check out Help menu > Key and Mouse Ref, if interested.
