Tracing a paper plan into Draw

[daveinfrance]

I am trying to make an electronic copy of a model railway track plan in Draw, and have previous experience some years ago of doing the same using Intergraph CAD software. I have succeeded in getting my paper plan onto a drawing as a Master and have drawn some things (rectangles, lines) over the top of some items on the plan, but circles and compound curves are defeating me. I can draw an arc in OO, but cannot get it to line up with the curve I am trying to trace over (I cannot seem to find the logic that drives the arc that can be drawn) - if I start on a point on the curve on my plan,or at the centre point of the radius for the curve neither draws an arc over the line I wish to copy. Can someone point me in the right direction before I go mad! :

[acknak]

Greetings and welcome to the community forum!

... I have succeeded in getting my paper plan onto a drawing as a Master ...

Interesting! That's a clever idea; I never thought of doing it that way.

The only problem I see is that you'll have to remove the plan at the end or else it will be visible under the drawing.

I usually manage this sort of project by adding a new layer for the original, then draw the copy on a different layer. This allows for easy toggling of the visibility and printing of the background layer. If the background layer is locked, Draw will not select any elements on that layer, so it doesn't interfere with drawing actions.

As far as drawing arcs, I assume that rail sections are always part of circular arcs? If so, Draw can do perfect circular arcs but not with the default configuration. You have to enable a separate tool palette.

For arbitrary curves, I agree with your consternation. I find Draw's curve tool impossible to use. I generally start tracing with a polygon: each click adds a new vertex, with straight lines connecting. Then, once I have the vertices, I convert the polyline to a curve and adjust the (bezier) handles to get the exact shape.

If you need help with the steps for that, just ask.

Edit: PS:

Draw can also trace curves automatically, but I find the results disappointing and usually end up doing my own.

[daveinfrance]

Thanks for the prompt reply acknak. I may have found up by using Master as the place for the plan, but this is something I used to do when making Powrpoint presentations or work.... Maybe placing the original on a layer which I can switch on and off would be better - any pointers to advice on this would be appreciated, as would your last point about drawing a polygon and then converting to a Bézier curve, which sounds similar to what I used to do on the CAD system. I've seen Bézier curves and Sussex out the Ellipse toolbar to get circle arcs, but am struggling to use them easily.......

[acknak]

Here are some steps. I'd suggest digging up the Draw Guide (oo.org/documentation ...) for more of the basics.

A background layer:
Insert > Layer ... enter a name OK. The new layer should be active (check the layer tabs just below/left the editing area. (You can make more space for the tabs if needed.)
Insert the image as usual, resize & align.
Lock the layer: Double-click the layer tab ... Locked: ON, OK

Switch back to the drawing layer (usually "Layout") and start drawing.

For tracing:
Draw a polyline: click the "Curve" palette on the Drawing toolbar, then select the "polygon" tool. Click+drag to start, then click for the second point. Following points can be added with just a click (no drag needed). Double-click finishes the polyline.

I generally aim for as few points (nodes/vertices) as necessary. You can always add points later.

Once you have the polyline finished and selected, do Modify > Convert > To Curve. No change is visible beyond the type of object (see the left side if the status bar).

Edit > Points ... or click the "Edit Points" button on the Drawing toolbar. You should see handles on each vertex now, and a new floating toolbar will appear. To change the shape of the curve: click on a node to select it; handles will appear on each side. Click on a handle and drag; the position of the handle will determine the shape of the curve as it leaves the node on that side.

If you're having trouble finding the handles, try clicking on a node and then clicking the "smooth" button on the floating toolbar. The handles should move to give a smooth curve across the node.

I would suggest playing around with it a bit before you start trying to trace something, just to get familiar with the process.

As far as using the circle arc, it is a bit awkward, especially as Draw doesn't support placing objects by their centers. If you have specific questions, just ask. If you can post a sample that may be easier than explaining.

Edit: PS:

For more on setting up the ellipse tool, see: viewtopic.php?f=11&t=83873

[daveinfrance]

Many thanks once again! Will have a other try tomorrow and see how things go.....