Drawing roads (on a map) in SU

S. Miley

Hi all,

This is my first post, I hope my question isn't too trivial, I did consult Google and tried my best to find out what to do with the available tools in SU 8. (Windows, free version)

I would like to draw roads on a map. The rough draft of the map is provided through a scanned image, which I have imported into SU. It's only a rough guide, so precision is not really a requirement (at least not yet).

I'll try to give a small overview of what I have tried, if anyone has suggestions, they're more than welcome.

My first attempt was to just draw an outline, and then try to make the lines very thick. I could create the outline, but it kept on filling with a solid color if I completed the shape. I couldn't find how to keep a shape from filling with a solid color, although I do think it would be somewhere in a toolbox.
Second attempt was to use the Scale tool on the first outline, and then the Offset tool on the scaled version. That way I had 2 figures which I could subtract from each other. Sadly, I need the Intersect method to realise that, and I only have the free version, so no luck there either.
Last thing I tried was drawing a square/rectangle perpendicular to my image, and using Line and Arc to draw some stretches of connected segments, and then using Follow Me to draw out a elongated shape along those segments.
Afterwards I reduced the height so it looked like a road.

So far this has been the most rewarding method. Only problem I'm facing is that I have some segments that interconnect (eg: a single point where multiple segments come together, an intersection). As you 'use up' a face when you start dragging the Follow Me tool, I still have a path exiting from the node, for which I have no 'start face' to use Follow Me on (as it was used the for the first segments).
Starting elsewhere and trying to overlap/connect the 2 roads didn't work either (see image).

Am I doing something wrong? Or am I not using the right tool for the job? I'd like to add buildings and benches and stuff later on, I thought drawing roads would be quite easy, but that seems not to be the case.

Here's an image of my third attempt (using Follow Me): http://img263.imageshack.us/img263/6961/screendl.png

TIG

Note that you can attach images and other files to your post - see below the typing pane.
There is no need to link off to an external file unless is is very large and won't attach here.
Even disallowed file types can be attached by zipping them.
What you need to do is have the image imported as a 'flat' face - as you appear to have done.
First scale it to approximately the right size.
Group it.
Edit the group.
Use the tapemeasure tool to pick two points in the image that are a known distance apart - e.g. the road width at a point might be 6.1m or 20' - as soon as you pick the second point the current distance is displayed in the VCB pane [usually along the bottom of the screen unless you have moved it!]: type in the correct value - e.g. 6.1m and you are prompted to scale everything in the group - answer 'Yes'. The group is now resized so that it is the required size - obviously if it were a CAD image rather than a scanned-in hand-drawn sketch it'd be more accurate!
So now you have the image at the right size.
Exit the edit and select the group and 'Lock' it. This will prevent you from accidentally erasing or moving it or changing it in any way [later you can Un-Lock it and erase/hide it as required].
Now use the tools to draw lines/arc/freehand-curves etc over the image. If you use arcs them an arc will look cyan if it is 'tangential' to another arc or an edge.
As you already know Sketchup automatically adds a face to an enclosed loop of edges/arcs etc that can take a face.
This can be annoying, but with practice you'll learn to leave the loop incomplete so that it doesn't 'face' - but if it does you can highlight just the face and press the <delete> key to erase it leaving the edges behind. You can undo unwanted new edges/arcs as you add them or highlight them and <delete> or use the Erase tool on them later.
In the initial stages I would try to extrude any faced loops into 3D 'blocks' as shown in your image.
Rather get an outline of edges and when you are happy with the form redraw over an edge here and there so that they 'face' as required.
If you are making the form slope in 3D then drawn some extra edges across junctions or transition points so the faces get split. Now you can either select a face and Move it up in the Z [blue] constrained with Shift /arrow keys by the desire distance WITH the Alt key pressed so the form 'auto-folds'. You can also select just an edge that forms the end of a road and Move that up/down in a similar way - in that case the road attached to it will slope along its length.
Once you have the road form in 3D as desired you can hide or smooth the edges across it so they aren't normally seen using the Erase tool +Shift[hide] or +Ctrl[smooth] - the difference is in the appearance of the surface. You can see hidden/smoothed lines by toggling Menu > View > Hidden Geometry 'on'. You can always select hidden/smoothed edges in this view-mode and Entity-Info un-check the boxes relating to hidden/smoothed etc...

S. Miley

Thanks TIG, for the very detailed information!

I'm still very new to modeling, so I have a lot to learn, but those pointers sure put me in the right direction!